Re: [PATCH v5 2/2] drm/i915: State readout and cross-checking for dp_m2_n2

[Vandana Kannan <vandana.kannan@intel.com>]

On Jun-18-2014 4:16 PM, Daniel Vetter wrote:
> On Wed, Jun 18, 2014 at 10:11:20AM +0530, Vandana Kannan wrote:
>> On Jun-17-2014 10:12 PM, Daniel Vetter wrote:
>>> On Tue, Jun 17, 2014 at 05:52:24PM +0300, Jani Nikula wrote:
>>>> On Mon, 16 Jun 2014, Vandana Kannan <vandana.kannan@intel.com> wrote:
>>>>> On Jun-13-2014 7:42 PM, Jani Nikula wrote:
>>>>>> On Thu, 22 May 2014, Vandana Kannan <vandana.kannan@intel.com> 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).
>>>>>>>
>>>>>>> v3: Modified call to get_m2_n2 which had dp_m_n as param by mistake.
>>>>>>> Compare dp_m_n and dp_m2_n2 for gen 7 and below. compare the structures
>>>>>>> based on DRRS state for gen 8 and above.
>>>>>>> Save and restore M2 N2 registers for gen 7 and below
>>>>>>>
>>>>>>> v4: For Gen>=8, check M_N registers against dp_m_n and dp_m2_n2 as there is
>>>>>>> only one set of M_N registers
>>>>>>>
>>>>>>> v5: Removed the chunk which saves and restores M2_N2 registers. Modified
>>>>>>> get_m_n() to get M2_N2 registers as well. Modified the macro which compares
>>>>>>> hw.dp_m_n against sw.dp_m2_n2/sw.dp_m_n for gen > 8.
>>>>>>>
>>>>>>> Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
>>>>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>>>> ---
>>>>>>>  drivers/gpu/drm/i915/intel_display.c | 68 +++++++++++++++++++++++++++++++-----
>>>>>>>  1 file changed, 60 insertions(+), 8 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>>>>>>> index cf3ad87..d593897 100644
>>>>>>> --- a/drivers/gpu/drm/i915/intel_display.c
>>>>>>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>>>>>> @@ -6945,7 +6945,8 @@ static void intel_pch_transcoder_get_m_n(struct intel_crtc *crtc,
>>>>>>>  
>>>>>>>  static void intel_cpu_transcoder_get_m_n(struct intel_crtc *crtc,
>>>>>>>  					 enum transcoder transcoder,
>>>>>>> -					 struct intel_link_m_n *m_n)
>>>>>>> +					 struct intel_link_m_n *m_n,
>>>>>>> +					 struct intel_link_m_n *m2_n2)
>>>>>>>  {
>>>>>>>  	struct drm_device *dev = crtc->base.dev;
>>>>>>>  	struct drm_i915_private *dev_priv = dev->dev_private;
>>>>>>> @@ -6959,6 +6960,15 @@ static void intel_cpu_transcoder_get_m_n(struct intel_crtc *crtc,
>>>>>>>  		m_n->gmch_n = I915_READ(PIPE_DATA_N1(transcoder));
>>>>>>>  		m_n->tu = ((I915_READ(PIPE_DATA_M1(transcoder))
>>>>>>>  			    & TU_SIZE_MASK) >> TU_SIZE_SHIFT) + 1;
>>>>>>> +		if (m2_n2 && INTEL_INFO(dev)->gen < 8) {
>>>>>>> +			m2_n2->link_m = I915_READ(PIPE_LINK_M2(transcoder));
>>>>>>> +			m2_n2->link_n =	I915_READ(PIPE_LINK_N2(transcoder));
>>>>>>> +			m2_n2->gmch_m =	I915_READ(PIPE_DATA_M2(transcoder))
>>>>>>> +					& ~TU_SIZE_MASK;
>>>>>>> +			m2_n2->gmch_n =	I915_READ(PIPE_DATA_N2(transcoder));
>>>>>>> +			m2_n2->tu = ((I915_READ(PIPE_DATA_M2(transcoder))
>>>>>>> +					& TU_SIZE_MASK) >> TU_SIZE_SHIFT) + 1;
>>>>>>> +		}
>>>>>>>  	} else {
>>>>>>>  		m_n->link_m = I915_READ(PIPE_LINK_M_G4X(pipe));
>>>>>>>  		m_n->link_n = I915_READ(PIPE_LINK_N_G4X(pipe));
>>>>>>> @@ -6977,14 +6987,15 @@ void intel_dp_get_m_n(struct intel_crtc *crtc,
>>>>>>>  		intel_pch_transcoder_get_m_n(crtc, &pipe_config->dp_m_n);
>>>>>>>  	else
>>>>>>>  		intel_cpu_transcoder_get_m_n(crtc, pipe_config->cpu_transcoder,
>>>>>>> -					     &pipe_config->dp_m_n);
>>>>>>> +					     &pipe_config->dp_m_n,
>>>>>>> +					     &pipe_config->dp_m2_n2);
>>>>>>>  }
>>>>>>>  
>>>>>>>  static void ironlake_get_fdi_m_n_config(struct intel_crtc *crtc,
>>>>>>>  					struct intel_crtc_config *pipe_config)
>>>>>>>  {
>>>>>>>  	intel_cpu_transcoder_get_m_n(crtc, pipe_config->cpu_transcoder,
>>>>>>> -				     &pipe_config->fdi_m_n);
>>>>>>> +				     &pipe_config->fdi_m_n, NULL);
>>>>>>>  }
>>>>>>>  
>>>>>>>  static void ironlake_get_pfit_config(struct intel_crtc *crtc,
>>>>>>> @@ -9485,6 +9496,15 @@ 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");
>>>>>>> @@ -9867,6 +9887,22 @@ intel_pipe_config_compare(struct drm_device *dev,
>>>>>>>  		return false; \
>>>>>>>  	}
>>>>>>>  
>>>>>>> +/* This is required for BDW+ where there is only one set of registers for
>>>>>>> + * switching between high and low RR.
>>>>>>> + * This macro can be used whenever a comparison has to be made between one
>>>>>>> + * hw state and multiple sw state variables.
>>>>>>> + */
>>>>>>> +#define PIPE_CONF_CHECK_I_ALT(name, alt_name) \
>>>>>>> +	if ((current_config->name != pipe_config->name) && \
>>>>>>> +		(current_config->alt_name != pipe_config->name)) { \
>>>>>>> +			DRM_ERROR("mismatch in " #name " " \
>>>>>>> +				  "(expected %i or %i, found %i)\n", \
>>>>>>> +				  current_config->name, \
>>>>>>> +				  current_config->alt_name, \
>>>>>>> +				  pipe_config->name); \
>>>>>>> +			return false; \
>>>>>>> +	}
>>>>>>> +
>>>>>>>  #define PIPE_CONF_CHECK_FLAGS(name, mask)	\
>>>>>>>  	if ((current_config->name ^ pipe_config->name) & (mask)) { \
>>>>>>>  		DRM_ERROR("mismatch in " #name "(" #mask ") "	   \
>>>>>>> @@ -9899,11 +9935,26 @@ 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);
>>>>>>> +
>>>>>>> +	if (INTEL_INFO(dev)->gen < 8) {
>>>>>>> +		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);
>>>>>>> +
>>>>>>> +		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);
>>>>>>> +	} else {
>>>>>>> +		PIPE_CONF_CHECK_I_ALT(dp_m_n.gmch_m, dp_m2_n2.gmch_m);
>>>>>>> +		PIPE_CONF_CHECK_I_ALT(dp_m_n.gmch_n, dp_m2_n2.gmch_n);
>>>>>>> +		PIPE_CONF_CHECK_I_ALT(dp_m_n.link_m, dp_m2_n2.link_m);
>>>>>>> +		PIPE_CONF_CHECK_I_ALT(dp_m_n.link_n, dp_m2_n2.link_n);
>>>>>>> +		PIPE_CONF_CHECK_I_ALT(dp_m_n.tu, dp_m2_n2.tu);
>>>>>>
>>>>>> If there's no downclock mode (e.g. because it's not eDP), this now
>>>>>> accepts register value 0 as okay for each state check. That's not cool.
>>>>>>
>>>>>> Perhaps drrs state should be part of pipe config.
>>>>>>
>>>>>> BR,
>>>>>> Jani.
>>>>>>
>>>>> Ok, shall I go ahead with the following approach?
>>>>>
>>>>> pipe_config{
>>>>> 	drrs_state;
>>>>> }
>>>>>
>>>>> in pipe_config_compare() {
>>>>> if gen < 8 {
>>>>> compare dp_m1_n1
>>>>> if drrs_state == seamless
>>>>> 	compare hw.dp_m2_n2 and sw.dp_m2_n2
>>>>> /* this drrs_state would be set only in edp_init_connector and only when
>>>>> a downclock_mode is found */
>>>>> }
>>>>> else
>>>>> 	compare hw.dp_m_n and sw.dp_m_n or sw.dp_m2_n2
>>>>> }
>>>>>
>>>>> drrs_state is stored in vbt struct and intel_dp as of now. some changes
>>>>> would be required around this to avoid saving this state at a third
>>>>> place (pipe_config).
>>>>> option 1. move drrs_state from intel_dp to dev_priv.
>>>>> option 2. move drrs_state from intel_dp to pipe_config.
>>>>>
>>>>> with the above changes, the patches accessing intel_dp->drrs_state would
>>>>> require changes.
>>>>>
>>>>> Please let me know your inputs on this.
>>>>
>>>> Daniel, any further thoughts on this? What fits best with future work?
>>>> Or go ahead with the patch as-is, even though it has the corner case?
>>>
>>> I think we should have a flag that says whether the 2nd set of regs is
>>> valid, then only use those if that's set. So amounts to adding a static
>>> copy to pipe_config, e.g. config.has_drrs -> 2nd set of values is valid.
>>>
>> I had introduced HAS_DRRS(dev) in patch#1 of this 2-patch series. I
>> could use that along with intel_crtc->config.has_dp_encoder check to
>> proceed with dp_m2_n2 comparison.
>> What are you thoughts on this?
> 
> Yeah, makes sense.
> -Daniel
> 
I will re-submit this patch with the change. I have rebased and resent
patch#1.

Additionally, once these 2 patches are ready for merge, I will rebase
and resend the remaining 3 DRRS related patches..

 1. drm/i915: Idleness detection  for DRRS
(http://lists.freedesktop.org/archives/intel-gfx/2014-April/043493.html)
2. drm/i915/bdw: Add support for DRRS to switch RR
(http://lists.freedesktop.org/archives/intel-gfx/2014-April/042804.html). This
would have to be  modified on top of the changes made in "drm/i915: Set
M2_N2 registers  during mode set".
3. drm/i915: Support for RR switching on VLV
(http://lists.freedesktop.org/archives/intel-gfx/2014-April/042805.html)

- Vandana