Re: [PATCH 3/6] drm/i915: Check PSR setup time vs. vblank length

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sat, 06 Aug 2016, Rodrigo Vivi <rodrigo.vivi@gmail.com> wrote:
> This patch is blocking PSR on panels that we know that our hardware support.

And it also fixes a regression on Linus' laptop, and it's been merged
upstream...

BR,
Jani.

>
> I wonder if:
> 1. This restrictions was for older platforms and spec is out dated
> 2. Or Spec is not documenting the restriction properly
> 3. Or we have some issue with out setup time calculation.
>
>
> On Tue, May 31, 2016 at 8:50 AM,  <ville.syrjala@linux.intel.com> wrote:
>> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>
>> Bspec says:
>> "Restriction : SRD must not be enabled when the PSR Setup time from DPCD
>> 00071h is greater than the time for vertical blank minus one line."
>>
>> Let's check for that and disallow PSR if we exceed the limit.
>>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_drv.h    |  2 ++
>>  drivers/gpu/drm/i915/intel_psr.c    | 19 ++++++++++++++++++-
>>  drivers/gpu/drm/i915/intel_sprite.c |  6 +++---
>>  3 files changed, 23 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index 9b5f6634c558..56ae3b78e25e 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -1672,6 +1672,8 @@ bool intel_sdvo_init(struct drm_device *dev,
>>
>>
>>  /* intel_sprite.c */
>> +int intel_usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
>> +                            int usecs);
>>  int intel_plane_init(struct drm_device *dev, enum pipe pipe, int plane);
>>  int intel_sprite_set_colorkey(struct drm_device *dev, void *data,
>>                               struct drm_file *file_priv);
>> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
>> index 29a09bf6bd18..aacd8d1767f2 100644
>> --- a/drivers/gpu/drm/i915/intel_psr.c
>> +++ b/drivers/gpu/drm/i915/intel_psr.c
>> @@ -327,6 +327,9 @@ static bool intel_psr_match_conditions(struct intel_dp *intel_dp)
>>         struct drm_i915_private *dev_priv = dev->dev_private;
>>         struct drm_crtc *crtc = dig_port->base.base.crtc;
>>         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>> +       const struct drm_display_mode *adjusted_mode =
>> +               &intel_crtc->config->base.adjusted_mode;
>> +       int psr_setup_time;
>>
>>         lockdep_assert_held(&dev_priv->psr.lock);
>>         WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>> @@ -365,11 +368,25 @@ static bool intel_psr_match_conditions(struct intel_dp *intel_dp)
>>         }
>>
>>         if (IS_HASWELL(dev) &&
>> -           intel_crtc->config->base.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE) {
>> +           adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) {
>>                 DRM_DEBUG_KMS("PSR condition failed: Interlaced is Enabled\n");
>>                 return false;
>>         }
>>
>> +       psr_setup_time = drm_dp_psr_setup_time(intel_dp->psr_dpcd);
>> +       if (psr_setup_time < 0) {
>> +               DRM_DEBUG_KMS("PSR condition failed: Invalid PSR setup time (0x%02x)\n",
>> +                             intel_dp->psr_dpcd[1]);
>> +               return false;
>> +       }
>> +
>> +       if (intel_usecs_to_scanlines(adjusted_mode, psr_setup_time) >
>> +           adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vdisplay - 1) {
>> +               DRM_DEBUG_KMS("PSR condition failed: PSR setup time (%d us) too long\n",
>> +                             psr_setup_time);
>> +               return false;
>> +       }
>> +
>>         dev_priv->psr.source_ok = true;
>>         return true;
>>  }
>> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
>> index 324ccb06397d..293b48007006 100644
>> --- a/drivers/gpu/drm/i915/intel_sprite.c
>> +++ b/drivers/gpu/drm/i915/intel_sprite.c
>> @@ -53,8 +53,8 @@ format_is_yuv(uint32_t format)
>>         }
>>  }
>>
>> -static int usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
>> -                             int usecs)
>> +int intel_usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
>> +                            int usecs)
>>  {
>>         /* paranoia */
>>         if (!adjusted_mode->crtc_htotal)
>> @@ -91,7 +91,7 @@ void intel_pipe_update_start(struct intel_crtc *crtc)
>>                 vblank_start = DIV_ROUND_UP(vblank_start, 2);
>>
>>         /* FIXME needs to be calibrated sensibly */
>> -       min = vblank_start - usecs_to_scanlines(adjusted_mode, 100);
>> +       min = vblank_start - intel_usecs_to_scanlines(adjusted_mode, 100);
>>         max = vblank_start - 1;
>>
>>         local_irq_disable();
>> --
>> 2.7.4
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Jani Nikula, Intel Open Source Technology Center
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