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

[Anusha]

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);
+	} 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;
+	}
 	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