[Intel-gfx] [PATCH v3] drm/core: Add drm_accurate_vblank_count, v3.

kbuild test robot lkp at intel.com
Tue Apr 12 16:43:27 UTC 2016


Hi Maarten,

[auto build test WARNING on drm/drm-next]
[also build test WARNING on v4.6-rc3 next-20160412]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Maarten-Lankhorst/drm-core-Add-drm_accurate_vblank_count-v3/20160412-223507
base:   git://people.freedesktop.org/~airlied/linux.git drm-next
reproduce: make htmldocs

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/i915/i915_irq.c:2663: warning: No description found for parameter 'fmt'
   include/drm/drm_crtc.h:364: warning: No description found for parameter 'mode_blob'
   include/drm/drm_crtc.h:779: warning: No description found for parameter 'name'
   include/drm/drm_crtc.h:1238: warning: No description found for parameter 'connector_id'
   include/drm/drm_crtc.h:1238: warning: No description found for parameter 'tile_blob_ptr'
   include/drm/drm_crtc.h:1277: warning: No description found for parameter 'rotation'
   include/drm/drm_crtc.h:1539: warning: No description found for parameter 'name'
   include/drm/drm_crtc.h:1539: warning: No description found for parameter 'mutex'
   include/drm/drm_crtc.h:1539: warning: No description found for parameter 'helper_private'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tile_idr'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'connector_ida'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'delayed_event'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'edid_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'dpms_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'path_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tile_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'plane_type_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'rotation_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_src_x'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_src_y'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_src_w'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_src_h'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_crtc_x'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_crtc_y'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_crtc_w'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_crtc_h'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_fb_id'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_crtc_id'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_active'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'prop_mode_id'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'dvi_i_subconnector_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'dvi_i_select_subconnector_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_subconnector_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_select_subconnector_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_mode_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_left_margin_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_right_margin_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_top_margin_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_bottom_margin_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_brightness_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_contrast_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_flicker_reduction_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_overscan_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_saturation_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'tv_hue_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'scaling_mode_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'aspect_ratio_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'dirty_info_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'suggested_x_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'suggested_y_property'
   include/drm/drm_crtc.h:2175: warning: No description found for parameter 'allow_fb_modifiers'
   drivers/gpu/drm/drm_atomic_helper.c:2924: warning: No description found for parameter 'start'
   drivers/gpu/drm/drm_atomic_helper.c:2924: warning: No description found for parameter 'start'
   drivers/gpu/drm/drm_atomic_helper.c:2924: warning: No description found for parameter 'start'
   drivers/gpu/drm/drm_atomic_helper.c:2924: warning: No description found for parameter 'start'
   include/drm/drm_dp_helper.h:749: warning: No description found for parameter 'i2c_nack_count'
   include/drm/drm_dp_helper.h:749: warning: No description found for parameter 'i2c_defer_count'
   drivers/gpu/drm/drm_dp_mst_topology.c:2356: warning: No description found for parameter 'connector'
   include/drm/drm_dp_mst_helper.h:92: warning: No description found for parameter 'cached_edid'
   include/drm/drm_dp_mst_helper.h:92: warning: No description found for parameter 'has_audio'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'max_dpcd_transaction_bytes'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'sink_count'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'total_slots'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'avail_slots'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'total_pbn'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'qlock'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'tx_msg_downq'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'tx_down_in_progress'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'payload_lock'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'proposed_vcpis'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'payloads'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'payload_mask'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'vcpi_mask'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'tx_waitq'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'work'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'tx_work'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'destroy_connector_list'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'destroy_connector_lock'
   include/drm/drm_dp_mst_helper.h:466: warning: No description found for parameter 'destroy_connector_work'
   drivers/gpu/drm/drm_dp_mst_topology.c:2356: warning: No description found for parameter 'connector'
   drivers/gpu/drm/drm_irq.c:176: warning: No description found for parameter 'flags'
>> drivers/gpu/drm/drm_irq.c:316: warning: Excess function parameter 'tv_ret' description in 'drm_accurate_vblank_count'
   include/drm/drmP.h:168: warning: No description found for parameter 'fmt'
   include/drm/drmP.h:184: warning: No description found for parameter 'fmt'
   include/drm/drmP.h:202: warning: No description found for parameter 'fmt'
   include/drm/drmP.h:247: warning: No description found for parameter 'dev'
   include/drm/drmP.h:247: warning: No description found for parameter 'data'
   include/drm/drmP.h:247: warning: No description found for parameter 'file_priv'
   include/drm/drmP.h:280: warning: No description found for parameter 'ioctl'
   include/drm/drmP.h:280: warning: No description found for parameter '_func'
   include/drm/drmP.h:280: warning: No description found for parameter '_flags'
   include/drm/drmP.h:362: warning: cannot understand function prototype: 'struct drm_lock_data '
   include/drm/drmP.h:415: warning: cannot understand function prototype: 'struct drm_driver '
   include/drm/drmP.h:672: warning: cannot understand function prototype: 'struct drm_info_list '
   include/drm/drmP.h:682: warning: cannot understand function prototype: 'struct drm_info_node '
   include/drm/drmP.h:692: warning: cannot understand function prototype: 'struct drm_minor '
   include/drm/drmP.h:740: warning: cannot understand function prototype: 'struct drm_device '
   drivers/gpu/drm/i915/intel_runtime_pm.c:2275: warning: No description found for parameter 'resume'
   drivers/gpu/drm/i915/intel_runtime_pm.c:2275: warning: No description found for parameter 'resume'
   drivers/gpu/drm/i915/i915_irq.c:2663: warning: No description found for parameter 'fmt'
   drivers/gpu/drm/i915/i915_irq.c:2663: warning: No description found for parameter 'fmt'
   drivers/gpu/drm/i915/i915_irq.c:2663: warning: No description found for parameter 'fmt'
   drivers/gpu/drm/i915/i915_irq.c:2663: warning: No description found for parameter 'fmt'
   drivers/gpu/drm/i915/i915_gem.c:421: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:421: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:421: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:686: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:686: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:686: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:767: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:767: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:767: warning: No description found for parameter 'args'
   drivers/gpu/drm/i915/i915_gem.c:767: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:1029: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:1029: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:1029: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:1245: warning: No description found for parameter 'rps'
   drivers/gpu/drm/i915/i915_gem.c:1459: warning: No description found for parameter 'req'
   drivers/gpu/drm/i915/i915_gem.c:1494: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:1494: warning: No description found for parameter 'readonly'
   drivers/gpu/drm/i915/i915_gem.c:1617: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:1617: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:1617: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:1680: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:1680: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:1680: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:1725: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:1725: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:1725: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:2013: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:2013: warning: No description found for parameter 'size'
   drivers/gpu/drm/i915/i915_gem.c:2013: warning: No description found for parameter 'tiling_mode'
   drivers/gpu/drm/i915/i915_gem.c:2013: warning: No description found for parameter 'fenced'
   drivers/gpu/drm/i915/i915_gem.c:2013: warning: Excess function parameter 'obj' description in 'i915_gem_get_gtt_alignment'
   drivers/gpu/drm/i915/i915_gem.c:2911: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_gem.c:3037: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:3087: warning: No description found for parameter 'dev'
   drivers/gpu/drm/i915/i915_gem.c:3087: warning: No description found for parameter 'data'
   drivers/gpu/drm/i915/i915_gem.c:3087: warning: No description found for parameter 'file'
   drivers/gpu/drm/i915/i915_gem.c:3087: warning: Excess function parameter 'DRM_IOCTL_ARGS' description in 'i915_gem_wait_ioctl'
   drivers/gpu/drm/i915/i915_gem.c:3459: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:3459: warning: No description found for parameter 'vm'
   drivers/gpu/drm/i915/i915_gem.c:3459: warning: No description found for parameter 'ggtt_view'
   drivers/gpu/drm/i915/i915_gem.c:3459: warning: No description found for parameter 'alignment'
   drivers/gpu/drm/i915/i915_gem.c:3459: warning: No description found for parameter 'flags'
   drivers/gpu/drm/i915/i915_gem.c:3714: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:3714: warning: No description found for parameter 'write'
   drivers/gpu/drm/i915/i915_gem.c:3789: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:3789: warning: No description found for parameter 'cache_level'
   drivers/gpu/drm/i915/i915_gem.c:4063: warning: No description found for parameter 'obj'
   drivers/gpu/drm/i915/i915_gem.c:4063: warning: No description found for parameter 'write'
   drivers/gpu/drm/i915/i915_cmd_parser.c:748: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:748: warning: Excess function parameter 'ring' description in 'i915_cmd_parser_init_ring'
   drivers/gpu/drm/i915/i915_cmd_parser.c:838: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:838: warning: Excess function parameter 'ring' description in 'i915_cmd_parser_fini_ring'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1034: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1034: warning: Excess function parameter 'ring' description in 'i915_needs_cmd_parser'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1186: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1186: warning: Excess function parameter 'ring' description in 'i915_parse_cmds'
   drivers/gpu/drm/i915/i915_cmd_parser.c:748: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:748: warning: Excess function parameter 'ring' description in 'i915_cmd_parser_init_ring'
   drivers/gpu/drm/i915/i915_cmd_parser.c:838: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:838: warning: Excess function parameter 'ring' description in 'i915_cmd_parser_fini_ring'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1034: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1034: warning: Excess function parameter 'ring' description in 'i915_needs_cmd_parser'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1186: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/i915_cmd_parser.c:1186: warning: Excess function parameter 'ring' description in 'i915_parse_cmds'
   drivers/gpu/drm/i915/intel_lrc.c:318: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/intel_lrc.c:318: warning: Excess function parameter 'ring' description in 'intel_lr_context_descriptor_update'
   drivers/gpu/drm/i915/intel_lrc.c:355: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/intel_lrc.c:355: warning: Excess function parameter 'ring' description in 'intel_execlists_ctx_id'
   drivers/gpu/drm/i915/intel_lrc.c:547: warning: No description found for parameter 'engine'
   drivers/gpu/drm/i915/intel_lrc.c:547: warning: Excess function parameter 'ring' description in 'intel_lrc_irq_handler'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: No description found for parameter 'params'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'dev' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'file' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'ring' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'ctx' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'batch_obj' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'exec_start' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:951: warning: Excess function parameter 'dispatch_flags' description in 'intel_execlists_submission'
   drivers/gpu/drm/i915/intel_lrc.c:1334: warning: No description found for parameter 'engine'

vim +316 drivers/gpu/drm/drm_irq.c

   170	 *
   171	 * Note: caller must hold dev->vbl_lock since this reads & writes
   172	 * device vblank fields.
   173	 */
   174	static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
   175					    unsigned long flags)
 > 176	{
   177		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
   178		u32 cur_vblank, diff;
   179		bool rc;
   180		struct timeval t_vblank;
   181		int count = DRM_TIMESTAMP_MAXRETRIES;
   182		int framedur_ns = vblank->framedur_ns;
   183	
   184		/*
   185		 * Interrupts were disabled prior to this call, so deal with counter
   186		 * wrap if needed.
   187		 * NOTE!  It's possible we lost a full dev->max_vblank_count + 1 events
   188		 * here if the register is small or we had vblank interrupts off for
   189		 * a long time.
   190		 *
   191		 * We repeat the hardware vblank counter & timestamp query until
   192		 * we get consistent results. This to prevent races between gpu
   193		 * updating its hardware counter while we are retrieving the
   194		 * corresponding vblank timestamp.
   195		 */
   196		do {
   197			cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
   198			rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);
   199		} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);
   200	
   201		if (dev->max_vblank_count != 0) {
   202			/* trust the hw counter when it's around */
   203			diff = (cur_vblank - vblank->last) & dev->max_vblank_count;
   204		} else if (rc && framedur_ns) {
   205			const struct timeval *t_old;
   206			u64 diff_ns;
   207	
   208			t_old = &vblanktimestamp(dev, pipe, vblank->count);
   209			diff_ns = timeval_to_ns(&t_vblank) - timeval_to_ns(t_old);
   210	
   211			/*
   212			 * Figure out how many vblanks we've missed based
   213			 * on the difference in the timestamps and the
   214			 * frame/field duration.
   215			 */
   216			diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
   217	
   218			if (diff == 0 && flags & DRM_CALLED_FROM_VBLIRQ)
   219				DRM_DEBUG_VBL("crtc %u: Redundant vblirq ignored."
   220					      " diff_ns = %lld, framedur_ns = %d)\n",
   221					      pipe, (long long) diff_ns, framedur_ns);
   222		} else {
   223			/* some kind of default for drivers w/o accurate vbl timestamping */
   224			diff = (flags & DRM_CALLED_FROM_VBLIRQ) != 0;
   225		}
   226	
   227		/*
   228		 * Within a drm_vblank_pre_modeset - drm_vblank_post_modeset
   229		 * interval? If so then vblank irqs keep running and it will likely
   230		 * happen that the hardware vblank counter is not trustworthy as it
   231		 * might reset at some point in that interval and vblank timestamps
   232		 * are not trustworthy either in that interval. Iow. this can result
   233		 * in a bogus diff >> 1 which must be avoided as it would cause
   234		 * random large forward jumps of the software vblank counter.
   235		 */
   236		if (diff > 1 && (vblank->inmodeset & 0x2)) {
   237			DRM_DEBUG_VBL("clamping vblank bump to 1 on crtc %u: diffr=%u"
   238				      " due to pre-modeset.\n", pipe, diff);
   239			diff = 1;
   240		}
   241	
   242		/*
   243		 * FIMXE: Need to replace this hack with proper seqlocks.
   244		 *
   245		 * Restrict the bump of the software vblank counter to a safe maximum
   246		 * value of +1 whenever there is the possibility that concurrent readers
   247		 * of vblank timestamps could be active at the moment, as the current
   248		 * implementation of the timestamp caching and updating is not safe
   249		 * against concurrent readers for calls to store_vblank() with a bump
   250		 * of anything but +1. A bump != 1 would very likely return corrupted
   251		 * timestamps to userspace, because the same slot in the cache could
   252		 * be concurrently written by store_vblank() and read by one of those
   253		 * readers without the read-retry logic detecting the collision.
   254		 *
   255		 * Concurrent readers can exist when we are called from the
   256		 * drm_vblank_off() or drm_vblank_on() functions and other non-vblank-
   257		 * irq callers. However, all those calls to us are happening with the
   258		 * vbl_lock locked to prevent drm_vblank_get(), so the vblank refcount
   259		 * can't increase while we are executing. Therefore a zero refcount at
   260		 * this point is safe for arbitrary counter bumps if we are called
   261		 * outside vblank irq, a non-zero count is not 100% safe. Unfortunately
   262		 * we must also accept a refcount of 1, as whenever we are called from
   263		 * drm_vblank_get() -> drm_vblank_enable() the refcount will be 1 and
   264		 * we must let that one pass through in order to not lose vblank counts
   265		 * during vblank irq off - which would completely defeat the whole
   266		 * point of this routine.
   267		 *
   268		 * Whenever we are called from vblank irq, we have to assume concurrent
   269		 * readers exist or can show up any time during our execution, even if
   270		 * the refcount is currently zero, as vblank irqs are usually only
   271		 * enabled due to the presence of readers, and because when we are called
   272		 * from vblank irq we can't hold the vbl_lock to protect us from sudden
   273		 * bumps in vblank refcount. Therefore also restrict bumps to +1 when
   274		 * called from vblank irq.
   275		 */
   276		if ((diff > 1) && (atomic_read(&vblank->refcount) > 1 ||
   277		    (flags & DRM_CALLED_FROM_VBLIRQ))) {
   278			DRM_DEBUG_VBL("clamping vblank bump to 1 on crtc %u: diffr=%u "
   279				      "refcount %u, vblirq %u\n", pipe, diff,
   280				      atomic_read(&vblank->refcount),
   281				      (flags & DRM_CALLED_FROM_VBLIRQ) != 0);
   282			diff = 1;
   283		}
   284	
   285		DRM_DEBUG_VBL("updating vblank count on crtc %u:"
   286			      " current=%u, diff=%u, hw=%u hw_last=%u\n",
   287			      pipe, vblank->count, diff, cur_vblank, vblank->last);
   288	
   289		if (diff == 0) {
   290			WARN_ON_ONCE(cur_vblank != vblank->last);
   291			return;
   292		}
   293	
   294		/*
   295		 * Only reinitialize corresponding vblank timestamp if high-precision query
   296		 * available and didn't fail, or we were called from the vblank interrupt.
   297		 * Otherwise reinitialize delayed at next vblank interrupt and assign 0
   298		 * for now, to mark the vblanktimestamp as invalid.
   299		 */
   300		if (!rc && (flags & DRM_CALLED_FROM_VBLIRQ) == 0)
   301			t_vblank = (struct timeval) {0, 0};
   302	
   303		store_vblank(dev, pipe, diff, &t_vblank, cur_vblank);
   304	}
   305	
   306	/**
   307	 * drm_accurate_vblank_count - retrieve the master vblank counter
   308	 * @crtc: which counter to retrieve
   309	 * @tv_ret: last time counter was updated
   310	 *
   311	 * This function is similar to @drm_crtc_vblank_count but this
   312	 * function interpolates to handle a race with vblank irq's.
   313	 */
   314	
   315	u32 drm_accurate_vblank_count(struct drm_crtc *crtc)
 > 316	{
   317		struct drm_device *dev = crtc->dev;
   318		u32 vblank, pipe = drm_crtc_index(crtc);
   319		unsigned long flags;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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