On Mon, Apr 23, 2018 at 07:56:58PM -0700, Dhinakaran Pandiyan wrote:
> Sink crc is calculated by the sink for static frames irrespective of
> what the driver sets in TEST_SINK_START dpcd. Since PSR is the only use
> case for sink crc, we don't really need the sink_crc_{start, stop} code.
> 
> The second problem with the current implementation is vblank waits.
> Enabling vblank interrupts triggers PSR exit, which means we aren't
> really reading the correct CRC values for PSR tests. vblank waits are
> replaced by delays.
> 
> With the changes made in this patch, sink CRC is available only for
> static frames. I have tested this on a SKL laptop with PSR panel.
> 
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c |   2 +-
>  drivers/gpu/drm/i915/intel_dp.c     | 114 
> ++++--------------------------------
>  drivers/gpu/drm/i915/intel_drv.h    |   3 +-
>  3 files changed, 15 insertions(+), 104 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index 2f05f5262bba..35fa1418cc07 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2784,7 +2784,7 @@ static int i915_sink_crc(struct seq_file *m, void *data)
>  
>               intel_dp = enc_to_intel_dp(state->best_encoder);
>  
> -             ret = intel_dp_sink_crc(intel_dp, crtc_state, crc);
> +             ret = intel_dp_sink_crc(intel_dp, crc);
>               if (ret)
>                       goto err;
>  
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 7dcc874b7d8f..7352ab631ea8 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3876,32 +3876,18 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
>                                       intel_dp->is_mst);
>  }
>  
> -static int intel_dp_sink_crc_stop(struct intel_dp *intel_dp,
> -                               struct intel_crtc_state *crtc_state, bool 
> disable_wa)
> +int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
>  {
> -     struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> -     struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> -     struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
> -     u8 buf;
> -     int ret = 0;
> -     int count = 0;
> -     int attempts = 10;
> +     int count = 0, ret = 0, attempts;
>  
> -     if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0) {
> -             DRM_DEBUG_KMS("Sink CRC couldn't be stopped properly\n");
> -             ret = -EIO;
> -             goto out;
> -     }
> +     for (attempts = 0; attempts < 3 && count == 0; attempts++) {
> +             u8 buf;
>  
> -     if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK,
> -                            buf & ~DP_TEST_SINK_START) < 0) {
> -             DRM_DEBUG_KMS("Sink CRC couldn't be stopped properly\n");
> -             ret = -EIO;
> -             goto out;
> -     }
> -
> -     do {
> -             intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
> +             /* Wait for approximately half a frame, we cannot wait for a

that should be dependend on the mode timings right?!
I mean, I'm not against some random value that matches most used cases,
but I believe the statement should be different.

> +              * vblank interrupt as it triggers PSR exit.
> +              */
> +             if (attempts)
> +                     usleep_range(8000, 8500);
>  
>               if (drm_dp_dpcd_readb(&intel_dp->aux,
>                                     DP_TEST_SINK_MISC, &buf) < 0) {
> @@ -3909,93 +3895,19 @@ static int intel_dp_sink_crc_stop(struct intel_dp 
> *intel_dp,
>                       goto out;
>               }
>               count = buf & DP_TEST_COUNT_MASK;
> -     } while (--attempts && count);
> -
> -     if (attempts == 0) {
> -             DRM_DEBUG_KMS("TIMEOUT: Sink CRC counter is not zeroed after 
> calculation is stopped\n");
> -             ret = -ETIMEDOUT;
>       }
>  
> - out:
> -     if (disable_wa)
> -             hsw_enable_ips(crtc_state);
> -     return ret;
> -}
> -
> -static int intel_dp_sink_crc_start(struct intel_dp *intel_dp,
> -                                struct intel_crtc_state *crtc_state)
> -{
> -     struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> -     struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> -     struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
> -     u8 buf;
> -     int ret;
> -
> -     if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK_MISC, &buf) < 0)
> -             return -EIO;
> -
> -     if (!(buf & DP_TEST_CRC_SUPPORTED))
> -             return -ENOTTY;
> -
> -     if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0)
> -             return -EIO;
> -
> -     if (buf & DP_TEST_SINK_START) {
> -             ret = intel_dp_sink_crc_stop(intel_dp, crtc_state, false);
> -             if (ret)
> -                     return ret;
> -     }
> -
> -     hsw_disable_ips(crtc_state);
> -
> -     if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK,
> -                            buf | DP_TEST_SINK_START) < 0) {
> -             hsw_enable_ips(crtc_state);
> -             return -EIO;
> -     }
> -
> -     intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
> -     return 0;
> -}
> -
> -int intel_dp_sink_crc(struct intel_dp *intel_dp, struct intel_crtc_state 
> *crtc_state, u8 *crc)
> -{
> -     struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> -     struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> -     struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
> -     u8 buf;
> -     int count, ret;
> -     int attempts = 6;
> -
> -     ret = intel_dp_sink_crc_start(intel_dp, crtc_state);
> -     if (ret)
> -             return ret;
> -
> -     do {
> -             intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
> -
> -             if (drm_dp_dpcd_readb(&intel_dp->aux,
> -                                   DP_TEST_SINK_MISC, &buf) < 0) {
> -                     ret = -EIO;
> -                     goto stop;
> -             }
> -             count = buf & DP_TEST_COUNT_MASK;
> -
> -     } while (--attempts && count == 0);
> -
> -     if (attempts == 0) {
> -             DRM_ERROR("Panel is unable to calculate any CRC after 6 
> vblanks\n");
> +     if (attempts == 3) {
>               ret = -ETIMEDOUT;
> -             goto stop;
> +             goto out;
>       }
>  
>       if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) != 6) {
>               ret = -EIO;
> -             goto stop;
> +             goto out;
>       }
>  
> -stop:
> -     intel_dp_sink_crc_stop(intel_dp, crtc_state, true);
> +out:
>       return ret;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> b/drivers/gpu/drm/i915/intel_drv.h
> index 44ed248f1fe9..cacee94749e2 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1644,8 +1644,7 @@ void intel_dp_sink_dpms(struct intel_dp *intel_dp, int 
> mode);
>  void intel_dp_encoder_reset(struct drm_encoder *encoder);
>  void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder);
>  void intel_dp_encoder_destroy(struct drm_encoder *encoder);
> -int intel_dp_sink_crc(struct intel_dp *intel_dp,
> -                   struct intel_crtc_state *crtc_state, u8 *crc);
> +int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc);
>  bool intel_dp_compute_config(struct intel_encoder *encoder,
>                            struct intel_crtc_state *pipe_config,
>                            struct drm_connector_state *conn_state);
> -- 
> 2.14.1
> 
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