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

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On May-15-2014 3:01 PM, Ville Syrjälä wrote:
> 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@xxxxxxxxx>
>>>>>>> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
>>>>>>> ---
>>>>>>>  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.
> 
Yes, I'm setting the registers in crtc_mode_set..
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