[Intel-gfx] [PATCH v2] drm/i915: State readout and cross-checking for dp_m2_n2

Ville Syrjälä ville.syrjala at linux.intel.com
Thu May 15 11:31:25 CEST 2014


On Thu, May 15, 2014 at 02:48:02PM +0530, Vandana Kannan wrote:
> On May-13-2014 3:10 PM, Vandana Kannan wrote:
> > On May-13-2014 2:28 PM, Daniel Vetter wrote:
> >> On Tue, May 13, 2014 at 01:56:04PM +0530, Vandana Kannan wrote:
> >>> On May-12-2014 3:57 PM, Ville Syrjälä wrote:
> >>>> On Mon, May 05, 2014 at 01:49:31PM +0530, Vandana Kannan wrote:
> >>>>> Adding relevant read out comparison code, in check_crtc_state, for the new
> >>>>> member of crtc_config, dp_m2_n2, which was introduced to store link_m_n
> >>>>> values for a DP downclock mode (if available). Suggested by Daniel.
> >>>>>
> >>>>> v2: Changed patch title.
> >>>>> Daniel's review comments incorporated.
> >>>>> Added relevant state readout code for M2_N2. dp_m2_n2 comparison to be done
> >>>>> only when high RR is not in use (This is because alternate m_n register
> >>>>> programming will be done only when low RR is being used).
> >>>>>
> >>>>> Signed-off-by: Vandana Kannan <vandana.kannan at intel.com>
> >>>>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> >>>>> ---
> >>>>>  drivers/gpu/drm/i915/intel_ddi.c     |  1 +
> >>>>>  drivers/gpu/drm/i915/intel_display.c | 72 +++++++++++++++++++++++++++++++++---
> >>>>>  drivers/gpu/drm/i915/intel_dp.c      |  2 +
> >>>>>  drivers/gpu/drm/i915/intel_drv.h     |  2 +
> >>>>>  4 files changed, 72 insertions(+), 5 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> >>>>> index 0ad4e96..6784f0b 100644
> >>>>> --- a/drivers/gpu/drm/i915/intel_ddi.c
> >>>>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> >>>>> @@ -1587,6 +1587,7 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> >>>>>  	case TRANS_DDI_MODE_SELECT_DP_MST:
> >>>>>  		pipe_config->has_dp_encoder = true;
> >>>>>  		intel_dp_get_m_n(intel_crtc, pipe_config);
> >>>>> +		intel_dp_get_m2_n2(intel_crtc, pipe_config);
> >>>>>  		break;
> >>>>>  	default:
> >>>>>  		break;
> >>>>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >>>>> index 797f01c..2e625eb 100644
> >>>>> --- a/drivers/gpu/drm/i915/intel_display.c
> >>>>> +++ b/drivers/gpu/drm/i915/intel_display.c
> >>>>> @@ -6670,6 +6670,34 @@ void intel_dp_get_m_n(struct intel_crtc *crtc,
> >>>>>  					     &pipe_config->dp_m_n);
> >>>>>  }
> >>>>>  
> >>>>> +void intel_dp_get_m2_n2(struct intel_crtc *crtc,
> >>>>> +		      struct intel_crtc_config *pipe_config)
> >>>>> +{
> >>>>> +	struct drm_device *dev = crtc->base.dev;
> >>>>> +	struct drm_i915_private *dev_priv = dev->dev_private;
> >>>>> +	enum transcoder transcoder = pipe_config->cpu_transcoder;
> >>>>> +
> >>>>> +	if (INTEL_INFO(dev)->gen >= 8) {
> >>>>> +		intel_cpu_transcoder_get_m_n(crtc, transcoder,
> >>>>> +						&pipe_config->dp_m_n);
> >>>>
> >>>> dm_m2_n2 surely? And why do we even want to do this?
> >>>>
> >>> My miss, will change this.
> >>> For Gen8, there is only one set of MN registers to be programmed for
> >>> high and low RR. Hence this check.
> >>>>> +	} else if (INTEL_INFO(dev)->gen > 6) {
> >>>>> +		pipe_config->dp_m2_n2.link_m =
> >>>>> +					I915_READ(PIPE_LINK_M2(transcoder));
> >>>>> +		pipe_config->dp_m2_n2.link_n =
> >>>>> +					I915_READ(PIPE_LINK_N2(transcoder));
> >>>>> +		pipe_config->dp_m2_n2.gmch_m =
> >>>>> +					I915_READ(PIPE_DATA_M2(transcoder))
> >>>>> +					& ~TU_SIZE_MASK;
> >>>>> +		pipe_config->dp_m2_n2.gmch_n =
> >>>>> +					I915_READ(PIPE_DATA_N2(transcoder));
> >>>>> +		pipe_config->dp_m2_n2.tu =
> >>>>> +					((I915_READ(PIPE_DATA_M2(transcoder))
> >>>>> +					& TU_SIZE_MASK) >> TU_SIZE_SHIFT) + 1;
> >>>>> +	}
> >>>>> +
> >>>>> +}
> >>>>>
> >>>>> +
> >>>>>  static void ironlake_get_fdi_m_n_config(struct intel_crtc *crtc,
> >>>>>  					struct intel_crtc_config *pipe_config)
> >>>>>  {
> >>>>> @@ -9169,6 +9197,15 @@ static void intel_dump_pipe_config(struct intel_crtc *crtc,
> >>>>>  		      pipe_config->dp_m_n.gmch_m, pipe_config->dp_m_n.gmch_n,
> >>>>>  		      pipe_config->dp_m_n.link_m, pipe_config->dp_m_n.link_n,
> >>>>>  		      pipe_config->dp_m_n.tu);
> >>>>> +
> >>>>> +	DRM_DEBUG_KMS("dp: %i, gmch_m2: %u, gmch_n2: %u, link_m2: %u, link_n2: %u, tu2: %u\n",
> >>>>> +		      pipe_config->has_dp_encoder,
> >>>>> +		      pipe_config->dp_m2_n2.gmch_m,
> >>>>> +		      pipe_config->dp_m2_n2.gmch_n,
> >>>>> +		      pipe_config->dp_m2_n2.link_m,
> >>>>> +		      pipe_config->dp_m2_n2.link_n,
> >>>>> +		      pipe_config->dp_m2_n2.tu);
> >>>>> +
> >>>>>  	DRM_DEBUG_KMS("requested mode:\n");
> >>>>>  	drm_mode_debug_printmodeline(&pipe_config->requested_mode);
> >>>>>  	DRM_DEBUG_KMS("adjusted mode:\n");
> >>>>> @@ -9533,6 +9570,14 @@ intel_pipe_config_compare(struct drm_device *dev,
> >>>>>  			  struct intel_crtc_config *current_config,
> >>>>>  			  struct intel_crtc_config *pipe_config)
> >>>>>  {
> >>>>> +	struct drm_i915_private *dev_priv = dev->dev_private;
> >>>>> +	struct intel_connector *intel_connector = dev_priv->drrs.connector;
> >>>>> +	struct intel_encoder *encoder = (intel_connector != NULL) ?
> >>>>> +			intel_attached_encoder(&intel_connector->base) :
> >>>>> +			NULL;
> >>>>> +	struct intel_dp *intel_dp = (encoder != NULL) ?
> >>>>> +			enc_to_intel_dp(&encoder->base) : NULL;
> >>>>> +
> >>>>>  #define PIPE_CONF_CHECK_X(name)	\
> >>>>>  	if (current_config->name != pipe_config->name) { \
> >>>>>  		DRM_ERROR("mismatch in " #name " " \
> >>>>> @@ -9583,11 +9628,28 @@ intel_pipe_config_compare(struct drm_device *dev,
> >>>>>  	PIPE_CONF_CHECK_I(fdi_m_n.tu);
> >>>>>  
> >>>>>  	PIPE_CONF_CHECK_I(has_dp_encoder);
> >>>>> -	PIPE_CONF_CHECK_I(dp_m_n.gmch_m);
> >>>>> -	PIPE_CONF_CHECK_I(dp_m_n.gmch_n);
> >>>>> -	PIPE_CONF_CHECK_I(dp_m_n.link_m);
> >>>>> -	PIPE_CONF_CHECK_I(dp_m_n.link_n);
> >>>>> -	PIPE_CONF_CHECK_I(dp_m_n.tu);
> >>>>> +
> >>>>> +
> >>>>> +	/* DP M1_N1 registers are used when DRRS is disabled or when high RR
> >>>>> +	 * is used. Else, DP M2_N2 registers are used. The following check
> >>>>> +	 * has been added to make sure a mismatch (if any) is displayed only
> >>>>> +	 * for a real difference and not because of DRRS state.
> >>>>> +	 */
> >>>>> +	if ((dev_priv->vbt.drrs_type == DRRS_NOT_SUPPORTED) ||
> >>>>> +		(dev_priv->vbt.drrs_type != DRRS_NOT_SUPPORTED && intel_dp &&
> >>>>> +		intel_dp->drrs_state.refresh_rate_type == DRRS_HIGH_RR)) {
> >>>>> +			PIPE_CONF_CHECK_I(dp_m_n.gmch_m);
> >>>>> +			PIPE_CONF_CHECK_I(dp_m_n.gmch_n);
> >>>>> +			PIPE_CONF_CHECK_I(dp_m_n.link_m);
> >>>>> +			PIPE_CONF_CHECK_I(dp_m_n.link_n);
> >>>>> +			PIPE_CONF_CHECK_I(dp_m_n.tu);
> >>>>> +	} else {
> >>>>> +		PIPE_CONF_CHECK_I(dp_m2_n2.gmch_m);
> >>>>> +		PIPE_CONF_CHECK_I(dp_m2_n2.gmch_n);
> >>>>> +		PIPE_CONF_CHECK_I(dp_m2_n2.link_m);
> >>>>> +		PIPE_CONF_CHECK_I(dp_m2_n2.link_n);
> >>>>> +		PIPE_CONF_CHECK_I(dp_m2_n2.tu);
> >>>>> +	}
> >>>>
> >>>> Can't we just check both dp_m_n and dp_m2_n2 always?
> >>>>
> >>> Daniel/Ville,
> >>>
> >>> pipe_config->dp_m2_n2 is populated along with pipe_config->dp_m_n in
> >>> compute_config(). while pipe_config dp_m_n values are programmed into MN
> >>> registers during the mode set, dp_m2_n2 values are programmed only when
> >>> low RR is used.
> >>> Given this, when PIPE_CONF_CHECK is done for dp_m2_n2, it would show a
> >>> mismatch (struct contains values to be programmed but registers still
> >>> have 0) and return.
> >>> The reason these checks were added was to avoid the scenario in which a
> >>> mismatch is highlighted when there is no real failure at all. For
> >>> example, DRRS is enabled on boot but the scenario to trigger low RR has
> >>> not yet occurred, dp_m2_n2 has been computed but M2_N2 registers are not
> >>> programmed in this case. There will be a mismatch in the pipe_config check.
> >>>
> >>> Changes can be made to set M2_N2 registers when dp_m2_n2 is populated
> >>> and toggle the bit (PIPECONF bit) to switch between high and low RR, but
> >>> this becomes invalid for gen8 and above where only 1 set of MN registers
> >>> are available.
> >>>
> >>> Please suggest some other way to handle this.
> >>> May be a quirk like the following?
> >>>
> >>>         /*
> >>>          * FIXME: BIOS likes to set up a cloned config with lvds+external
> >>>          * screen. Since we don't yet re-compute the pipe config when moving
> >>>          * just the lvds port away to another pipe the sw tracking won't
> >>> match.
> >>>          *
> >>>          * Proper atomic modesets with recomputed global state will fix
> >>> this.
> >>>          * Until then just don't check gmch state for inherited modes.
> >>>          */
> >>>         if (!PIPE_CONF_QUIRK(PIPE_CONFIG_QUIRK_INHERITED_MODE)) {
> >>>
> >>> Or go ahead with checking dp_m_n and dp_m2_n2 always ?
> >>> Please let me know..
> >>
> >> I think for BDW we should check whether the hw values match _either_
> >> dp_m_n or dp_m2_n2. But for hsw and earlier we should check both.
> >>
> >> That leaves us with the slightly awkward issue of recovering DRRS state on
> >> bdw. But I think since we sprinkle idle/busy calls all over the place this
> >> is a problem we can just ignore ;-)
> >> -Daniel
> >>
> > 
> > Ok, So I will make the following changes and resend..
> > 1. in compute_config(), for gen < 8, set M2_N2 registers (instead of
> > doing it in intel_dp_set_drrs_state()).
> > 2. in intel_pipe_config_compare(), include your inputs given above..
> > -Vandana
> 
> hi Daniel,
> I see a few issues with this approach of setting M2 N2 registers ahead
> and just toggling the bit to switch between refresh rates (for gen 7 and
> below)..
> 
> writing into M2_N2 registers in compute_config() would fail when system
> resumes from sleep. to overcome this, setting M2 N2 can be done in
> crtc_mode_set functions (similar to set_m_n).

Don't modify anything but the new pipe config in compute_config. As
the name suggests it's just supposed to compute the new state, not
apply it.

-- 
Ville Syrjälä
Intel OTC



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