drm: drm_atomic_helper: Add a new helper to deal with the writeback connector validation

Add a helper function to validate the connector configuration received in
the encoder atomic_check by the drivers.

So the drivers don't need to do these common validations themselves.

V2: Move the format verification to a new helper at the drm_atomic_helper.c
    (Thomas Zimmermann).
V3: Format check improvements (Leandro Ribeiro).
    Minor improvements(Thomas Zimmermann).
V5: Fix some grammar issues in the commit message (André Almeida).

Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Igor Torrente <igormtorrente@gmail.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220905190811.25024-4-igormtorrente@gmail.com

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index d36720f419f7..ee5fea48b5cb 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -786,6 +786,45 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
 
 /**
+ * drm_atomic_helper_check_wb_connector_state() - Check writeback encoder state
+ * @encoder: encoder state to check
+ * @conn_state: connector state to check
+ *
+ * Checks if the writeback connector state is valid, and returns an error if it
+ * isn't.
+ *
+ * RETURNS:
+ * Zero for success or -errno
+ */
+int
+drm_atomic_helper_check_wb_encoder_state(struct drm_encoder *encoder,
+					 struct drm_connector_state *conn_state)
+{
+	struct drm_writeback_job *wb_job = conn_state->writeback_job;
+	struct drm_property_blob *pixel_format_blob;
+	struct drm_framebuffer *fb;
+	size_t i, nformats;
+	u32 *formats;
+
+	if (!wb_job || !wb_job->fb)
+		return 0;
+
+	pixel_format_blob = wb_job->connector->pixel_formats_blob_ptr;
+	nformats = pixel_format_blob->length / sizeof(u32);
+	formats = pixel_format_blob->data;
+	fb = wb_job->fb;
+
+	for (i = 0; i < nformats; i++)
+		if (fb->format->format == formats[i])
+			return 0;
+
+	drm_dbg_kms(encoder->dev, "Invalid pixel format %p4cc\n", &fb->format->format);
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(drm_atomic_helper_check_wb_encoder_state);
+
+/**
  * drm_atomic_helper_check_plane_state() - Check plane state for validity
  * @plane_state: plane state to check
  * @crtc_state: CRTC state to check