Re: [PATCH] drm/i915: Kill sink_crc for good

[Dhinakaran Pandiyan <dhinakaran.pandiyan@gmail.com>]

On Thursday, July 5, 2018 12:25:28 PM PDT Rodrigo Vivi wrote:
> It was originally introduced following the VESA spec in order to validate
> PSR.
> 
> However we found so many issues around sink_crc that instead of helping PSR
> development it only brought another layer of trouble to the table.
> 
> So, sink_crc has been a black whole for us in question of time, effort and
> hope.
> 
> First of the problems is that HW statement is clear: "Do not attempt to use
> aux communication with PSR enabled". So the main reason behind sink_crc is
> already compromised.
> 
> For a while we had hope on the aux-mutex could workaround this problem on
> SKL+ platforms, but that mutex was not reliable, not tested,
> and we shouldn't use according to HW engineers.
> 
> Also, nor source, nor sink designed and implemented the sink_crc to be used
> like we are trying to use here.
> 
> Well, the sink side of things is also apparently not prepared for this
> case. Each panel that we tried seemed to have a different behavior with same
> code and same source.
> 
> So, for all the time we lost on trying to ducktape all these different
> issues I believe it is now time to move PSR to a more reliable validation.
> Maybe not a perfect one as we dreamed for this sink_crc, but at least more
> reliable.
> 
Good riddance.
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>

> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c |  81 ------------------
>  drivers/gpu/drm/i915/intel_dp.c     | 123 ----------------------------
>  drivers/gpu/drm/i915/intel_drv.h    |   2 -
>  3 files changed, 206 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c index f6142d78ede4..e8fa106a3655
> 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2761,86 +2761,6 @@ DEFINE_SIMPLE_ATTRIBUTE(i915_edp_psr_debug_fops,
>  			i915_edp_psr_debug_get, i915_edp_psr_debug_set,
>  			"%llu\n");
> 
> -static int i915_sink_crc(struct seq_file *m, void *data)
> -{
> -	struct drm_i915_private *dev_priv = node_to_i915(m->private);
> -	struct drm_device *dev = &dev_priv->drm;
> -	struct intel_connector *connector;
> -	struct drm_connector_list_iter conn_iter;
> -	struct intel_dp *intel_dp = NULL;
> -	struct drm_modeset_acquire_ctx ctx;
> -	int ret;
> -	u8 crc[6];
> -
> -	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
> -
> -	drm_connector_list_iter_begin(dev, &conn_iter);
> -
> -	for_each_intel_connector_iter(connector, &conn_iter) {
> -		struct drm_crtc *crtc;
> -		struct drm_connector_state *state;
> -		struct intel_crtc_state *crtc_state;
> -
> -		if (connector->base.connector_type != DRM_MODE_CONNECTOR_eDP)
> -			continue;
> -
> -retry:
> -		ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
> -		if (ret)
> -			goto err;
> -
> -		state = connector->base.state;
> -		if (!state->best_encoder)
> -			continue;
> -
> -		crtc = state->crtc;
> -		ret = drm_modeset_lock(&crtc->mutex, &ctx);
> -		if (ret)
> -			goto err;
> -
> -		crtc_state = to_intel_crtc_state(crtc->state);
> -		if (!crtc_state->base.active)
> -			continue;
> -
> -		/*
> -		 * We need to wait for all crtc updates to complete, to make
> -		 * sure any pending modesets and plane updates are completed.
> -		 */
> -		if (crtc_state->base.commit) {
> -			ret =
> wait_for_completion_interruptible(&crtc_state->base.commit->hw_done); -
> -			if (ret)
> -				goto err;
> -		}
> -
> -		intel_dp = enc_to_intel_dp(state->best_encoder);
> -
> -		ret = intel_dp_sink_crc(intel_dp, crtc_state, crc);
> -		if (ret)
> -			goto err;
> -
> -		seq_printf(m, "%02x%02x%02x%02x%02x%02x\n",
> -			   crc[0], crc[1], crc[2],
> -			   crc[3], crc[4], crc[5]);
> -		goto out;
> -
> -err:
> -		if (ret == -EDEADLK) {
> -			ret = drm_modeset_backoff(&ctx);
> -			if (!ret)
> -				goto retry;
> -		}
> -		goto out;
> -	}
> -	ret = -ENODEV;
> -out:
> -	drm_connector_list_iter_end(&conn_iter);
> -	drm_modeset_drop_locks(&ctx);
> -	drm_modeset_acquire_fini(&ctx);
> -
> -	return ret;
> -}
> -
>  static int i915_energy_uJ(struct seq_file *m, void *data)
>  {
>  	struct drm_i915_private *dev_priv = node_to_i915(m->private);
> @@ -4784,7 +4704,6 @@ static const struct drm_info_list i915_debugfs_list[]
> = { {"i915_ppgtt_info", i915_ppgtt_info, 0},
>  	{"i915_llc", i915_llc, 0},
>  	{"i915_edp_psr_status", i915_edp_psr_status, 0},
> -	{"i915_sink_crc_eDP1", i915_sink_crc, 0},
>  	{"i915_energy_uJ", i915_energy_uJ, 0},
>  	{"i915_runtime_pm_status", i915_runtime_pm_status, 0},
>  	{"i915_power_domain_info", i915_power_domain_info, 0},
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c index 5be07e1d816d..efdd4b408d51 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3905,129 +3905,6 @@ 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)
> -{
> -	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;
> -
> -	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;
> -	}
> -
> -	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);
> -
> -		if (drm_dp_dpcd_readb(&intel_dp->aux,
> -				      DP_TEST_SINK_MISC, &buf) < 0) {
> -			ret = -EIO;
> -			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");
> -		ret = -ETIMEDOUT;
> -		goto stop;
> -	}
> -
> -	if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) {
> -		ret = -EIO;
> -		goto stop;
> -	}
> -
> -stop:
> -	intel_dp_sink_crc_stop(intel_dp, crtc_state, true);
> -	return ret;
> -}
> -
>  static bool
>  intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
>  {
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h index e09b42d91d1e..8e6ee2fe66e4 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1665,8 +1665,6 @@ 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);
>  bool intel_dp_compute_config(struct intel_encoder *encoder,
>  			     struct intel_crtc_state *pipe_config,
>  			     struct drm_connector_state *conn_state);


_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx