[Intel-gfx] [PATCH v2] drm/probe_helper: sort out poll_running vs poll_enabled

Dmitry Baryshkov dmitry.baryshkov at linaro.org
Tue Jan 24 10:46:07 UTC 2023 

On 24/01/2023 10:55, Jani Nikula wrote:
> On Wed, 18 Jan 2023, Dmitry Baryshkov <dmitry.baryshkov at linaro.org> wrote:
>> There are two flags attemting to guard connector polling:
>> poll_enabled and poll_running. While poll_enabled semantics is clearly
>> defined and fully adhered (mark that drm_kms_helper_poll_init() was
>> called and not finalized by the _fini() call), the poll_running flag
>> doesn't have such clearliness.
>>
>> This flag is used only in drm_helper_probe_single_connector_modes() to
>> guard calling of drm_kms_helper_poll_enable, it doesn't guard the
>> drm_kms_helper_poll_fini(), etc. Change it to only be set if the polling
>> is actually running. Tie HPD enablement to this flag.
>>
>> This fixes the following warning reported after merging the HPD series:
>>
>> Hot plug detection already enabled
>> WARNING: CPU: 2 PID: 9 at drivers/gpu/drm/drm_bridge.c:1257 drm_bridge_hpd_enable+0x94/0x9c [drm]
>> Modules linked in: videobuf2_memops snd_soc_simple_card snd_soc_simple_card_utils fsl_imx8_ddr_perf videobuf2_common snd_soc_imx_spdif adv7511 etnaviv imx8m_ddrc imx_dcss mc cec nwl_dsi gov
>> CPU: 2 PID: 9 Comm: kworker/u8:0 Not tainted 6.2.0-rc2-15208-g25b283acd578 #6
>> Hardware name: NXP i.MX8MQ EVK (DT)
>> Workqueue: events_unbound deferred_probe_work_func
>> pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> pc : drm_bridge_hpd_enable+0x94/0x9c [drm]
>> lr : drm_bridge_hpd_enable+0x94/0x9c [drm]
>> sp : ffff800009ef3740
>> x29: ffff800009ef3740 x28: ffff000009331f00 x27: 0000000000001000
>> x26: 0000000000000020 x25: ffff800001148ed8 x24: ffff00000a8fe000
>> x23: 00000000fffffffd x22: ffff000005086348 x21: ffff800001133ee0
>> x20: ffff00000550d800 x19: ffff000005086288 x18: 0000000000000006
>> x17: 0000000000000000 x16: ffff8000096ef008 x15: 97ffff2891004260
>> x14: 2a1403e194000000 x13: 97ffff2891004260 x12: 2a1403e194000000
>> x11: 7100385f29400801 x10: 0000000000000aa0 x9 : ffff800008112744
>> x8 : ffff000000250b00 x7 : 0000000000000003 x6 : 0000000000000011
>> x5 : 0000000000000000 x4 : ffff0000bd986a48 x3 : 0000000000000001
>> x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000000250000
>> Call trace:
>>   drm_bridge_hpd_enable+0x94/0x9c [drm]
>>   drm_bridge_connector_enable_hpd+0x2c/0x3c [drm_kms_helper]
>>   drm_kms_helper_poll_enable+0x94/0x10c [drm_kms_helper]
>>   drm_helper_probe_single_connector_modes+0x1a8/0x510 [drm_kms_helper]
>>   drm_client_modeset_probe+0x204/0x1190 [drm]
>>   __drm_fb_helper_initial_config_and_unlock+0x5c/0x4a4 [drm_kms_helper]
>>   drm_fb_helper_initial_config+0x54/0x6c [drm_kms_helper]
>>   drm_fbdev_client_hotplug+0xd0/0x140 [drm_kms_helper]
>>   drm_fbdev_generic_setup+0x90/0x154 [drm_kms_helper]
>>   dcss_kms_attach+0x1c8/0x254 [imx_dcss]
>>   dcss_drv_platform_probe+0x90/0xfc [imx_dcss]
>>   platform_probe+0x70/0xcc
>>   really_probe+0xc4/0x2e0
>>   __driver_probe_device+0x80/0xf0
>>   driver_probe_device+0xe0/0x164
>>   __device_attach_driver+0xc0/0x13c
>>   bus_for_each_drv+0x84/0xe0
>>   __device_attach+0xa4/0x1a0
>>   device_initial_probe+0x1c/0x30
>>   bus_probe_device+0xa4/0xb0
>>   deferred_probe_work_func+0x90/0xd0
>>   process_one_work+0x200/0x474
>>   worker_thread+0x74/0x43c
>>   kthread+0xfc/0x110
>>   ret_from_fork+0x10/0x20
>> ---[ end trace 0000000000000000 ]---
>>
>> Reported-by: Laurentiu Palcu <laurentiu.palcu at oss.nxp.com>
>> Fixes: c8268795c9a9 ("drm/probe-helper: enable and disable HPD on connectors")
>> Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>
>> Tested-by: Chen-Yu Tsai <wenst at chromium.org>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>> ---
>>
>> Changes since v1:
>> - Fixed drm_kms_helper_enable_hpd() to call enable_hpd() instead of
>>    disable_hpd().
>>
>> ---
>>   drivers/gpu/drm/drm_probe_helper.c | 110 +++++++++++++++++------------
>>   1 file changed, 63 insertions(+), 47 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
>> index 7973f2589ced..04754bb7b131 100644
>> --- a/drivers/gpu/drm/drm_probe_helper.c
>> +++ b/drivers/gpu/drm/drm_probe_helper.c
>> @@ -222,6 +222,45 @@ drm_connector_mode_valid(struct drm_connector *connector,
>>   	return ret;
>>   }
>>   
>> +static void drm_kms_helper_disable_hpd(struct drm_device *dev)
>> +{
>> +	struct drm_connector *connector;
>> +	struct drm_connector_list_iter conn_iter;
>> +
>> +	drm_connector_list_iter_begin(dev, &conn_iter);
>> +	drm_for_each_connector_iter(connector, &conn_iter) {
>> +		const struct drm_connector_helper_funcs *funcs =
>> +			connector->helper_private;
>> +
>> +		if (funcs && funcs->disable_hpd)
>> +			funcs->disable_hpd(connector);
>> +	}
>> +	drm_connector_list_iter_end(&conn_iter);
>> +}
>> +
>> +static bool drm_kms_helper_enable_hpd(struct drm_device *dev)
>> +{
>> +	bool poll = false;
>> +	struct drm_connector *connector;
>> +	struct drm_connector_list_iter conn_iter;
>> +
>> +	drm_connector_list_iter_begin(dev, &conn_iter);
>> +	drm_for_each_connector_iter(connector, &conn_iter) {
>> +		const struct drm_connector_helper_funcs *funcs =
>> +			connector->helper_private;
>> +
>> +		if (funcs && funcs->enable_hpd)
>> +			funcs->enable_hpd(connector);
>> +
>> +		if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
>> +					 DRM_CONNECTOR_POLL_DISCONNECT))
>> +			poll = true;
>> +	}
>> +	drm_connector_list_iter_end(&conn_iter);
>> +
>> +	return poll;
>> +}
>> +
>>   #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
>>   /**
>>    * drm_kms_helper_poll_enable - re-enable output polling.
>> @@ -241,26 +280,14 @@ drm_connector_mode_valid(struct drm_connector *connector,
>>   void drm_kms_helper_poll_enable(struct drm_device *dev)
>>   {
>>   	bool poll = false;
>> -	struct drm_connector *connector;
>> -	struct drm_connector_list_iter conn_iter;
>>   	unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
>>   
>> -	if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
>> +	if (!dev->mode_config.poll_enabled ||
>> +	    !drm_kms_helper_poll ||
>> +	    dev->mode_config.poll_running)
>>   		return;
>>   
>> -	drm_connector_list_iter_begin(dev, &conn_iter);
>> -	drm_for_each_connector_iter(connector, &conn_iter) {
>> -		const struct drm_connector_helper_funcs *funcs =
>> -			connector->helper_private;
>> -
>> -		if (funcs && funcs->enable_hpd)
>> -			funcs->enable_hpd(connector);
>> -
>> -		if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
>> -					 DRM_CONNECTOR_POLL_DISCONNECT))
>> -			poll = true;
>> -	}
>> -	drm_connector_list_iter_end(&conn_iter);
>> +	poll = drm_kms_helper_enable_hpd(dev);
> 
> I'd really like to see these non-functional abstractions to functions
> separated from the actual functional fix. There's too much going on in
> the same patch here.

Done in v3

-- 
With best wishes
Dmitry

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