[PATCH] drm/i915/dsc: Add Per connector debugfs node for DSC BPP enable

[Manasi Navare]

On Thu, May 30, 2019 at 01:37:52PM -0700, Anusha wrote:
> From: Anusha Srivatsa <anusha.srivatsa at intel.com>
> 
> DSC can be supported per DP connector. This patch creates
> a per connector debugfs node to expose the Input and
> Compressed BPP.
> 
> The same node can be used from userspace to force
> DSC to a certain BPP.
> 
> force_dsc_bpp is written through this debugfs
> node to force DSC BPP to all accepted values
> 
> Cc: Manasi Navare <manasi.d.navare at intel.com>
> Signed-off-by: Anusha Srivatsa <anusha.srivatsa at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 102 +++++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/intel_dp.c     |   4 ++
>  drivers/gpu/drm/i915/intel_drv.h    |   1 +
>  3 files changed, 106 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 74afdeff2245..d36ebb5c957a 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4900,6 +4900,98 @@ static const struct file_operations i915_dsc_fec_support_fops = {
>  	.write = i915_dsc_fec_support_write
>  };
>  
> +static int i915_dsc_bpp_slice_support_show(struct seq_file *m, void *data)
> +{
> +	struct drm_connector *connector = m->private;
> +	struct drm_device *dev = connector->dev;
> +	struct drm_crtc *crtc;
> +	struct intel_dp *intel_dp;
> +	struct drm_modeset_acquire_ctx ctx;
> +	struct intel_crtc_state *crtc_state = NULL;
> +	int ret = 0;
> +	bool try_again = false;
> +
> +	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
> +
> +	do {
> +		try_again = false;
> +		ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
> +				       &ctx);
> +		if (ret) {
> +			ret = -EINTR;
> +			break;
> +		}
> +		crtc = connector->state->crtc;
> +		if (connector->status != connector_status_connected || !crtc) {
> +			ret = -ENODEV;
> +			break;
> +		}
> +		ret = drm_modeset_lock(&crtc->mutex, &ctx);
> +		if (ret == -EDEADLK) {
> +			ret = drm_modeset_backoff(&ctx);
> +			if (!ret) {
> +				try_again = true;
> +				continue;
> +			}
> +			break;
> +		} else if (ret) {
> +			break;
> +		}
> +		intel_dp = enc_to_intel_dp(&intel_attached_encoder(connector)->base);
> +		crtc_state = to_intel_crtc_state(crtc->state);
> +		seq_printf(m, "Input_BPP: %d\n", crtc_state->pipe_bpp);
> +		seq_printf(m, "Compressed_BPP: %d\n", crtc_state->dsc_params.compressed_bpp);

You will need to expose even the max dsc bpp supported for eDP here and use that as upper bound
for the dsc bpp array in the IGT for eDP since in case of eDP we obtain the max bpp from the dpcd
unlike for DP

> +	} while (try_again);
> +
> +	drm_modeset_drop_locks(&ctx);
> +	drm_modeset_acquire_fini(&ctx);
> +
> +	return ret;
> +}
> +
> +static ssize_t i915_dsc_bpp_slice_support_write(struct file *file,
> +						const char __user *ubuf,
> +						size_t len, loff_t *offp)
> +{
> +	int dsc_bpp = 0;
> +	int ret;
> +	struct drm_connector *connector =
> +		((struct seq_file *)file->private_data)->private;
> +	struct intel_encoder *encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> +
> +	if (len == 0)
> +		return 0;
> +
> +	DRM_DEBUG_DRIVER("Copied %zu bytes from user to force BPP\n",
> +			 len);
> +
> +	ret = kstrtoint_from_user(ubuf, len, 0, &dsc_bpp);
> +
> +	intel_dp->force_dsc_bpp = dsc_bpp;
> +	if (ret < 0)
> +		return ret;
> +
> +	*offp += len;
> +	return len;
> +}
> +
> +static int i915_dsc_bpp_slice_support_open(struct inode *inode,
> +					   struct file *file)
> +{
> +	return single_open(file, i915_dsc_bpp_slice_support_show,
> +			   inode->i_private);
> +}
> +
> +static const struct file_operations i915_dsc_bpp_slice_support_fops = {
> +	.owner = THIS_MODULE,
> +	.open = i915_dsc_bpp_slice_support_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +	.write = i915_dsc_bpp_slice_support_write
> +};
> +
>  /**
>   * i915_debugfs_connector_add - add i915 specific connector debugfs files
>   * @connector: pointer to a registered drm_connector
> @@ -4939,9 +5031,17 @@ int i915_debugfs_connector_add(struct drm_connector *connector)
>  
>  	if (INTEL_GEN(dev_priv) >= 10 &&
>  	    (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> -	     connector->connector_type == DRM_MODE_CONNECTOR_eDP))
> +	     connector->connector_type == DRM_MODE_CONNECTOR_eDP)) {
>  		debugfs_create_file("i915_dsc_fec_support", S_IRUGO, root,
>  				    connector, &i915_dsc_fec_support_fops);
> +	}
> +
> +	if (INTEL_GEN(dev_priv) >= 10 &&
> +	    (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> +	     connector->connector_type == DRM_MODE_CONNECTOR_eDP)) {
> +		debugfs_create_file("i915_dsc_bpp_slice_support", S_IRUGO, root,
> +				    connector, &i915_dsc_bpp_slice_support_fops);
> +	}
>  
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 24b56b2a76c8..92b050e5013a 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2003,6 +2003,10 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  	}
>  
>  	pipe_config->dsc_params.compression_enable = true;
> +	if (intel_dp->force_dsc_bpp) {
> +		DRM_ERROR("DSC BPC forced to %d", intel_dp->force_dsc_bpp);
> +		pipe_config->dsc_params.compressed_bpp = intel_dp->force_dsc_bpp;
> +	}

This forcing should happen where we get compressed_bpp from intel_dp_dsc_get_output_bpp
because then we compute dsc params based on thsi bpp value and then set compression_enable to true at the end.

Also i think it only makes sense to run this bpp test for eDP because in case of dp we compute the optimum output BPP
based on lot of parameters like the small joiner ram limits, link BW etc.

Manasi

>  	DRM_DEBUG_KMS("DP DSC computed with Input Bpp = %d "
>  		      "Compressed Bpp = %d Slice Count = %d\n",
>  		      pipe_config->pipe_bpp,
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 0dcc03592d6e..06e7ff2e61b0 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1199,6 +1199,7 @@ struct intel_dp {
>  
>  	/* Display stream compression testing */
>  	bool force_dsc_en;
> +	int force_dsc_bpp;
>  };
>  
>  enum lspcon_vendor {
> -- 
> 2.17.1
>