[PATCH v5 4/9] drm: drm_atomic_helper: Add a new helper to deal with the writeback connector validation

[Igor Torrente]

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

So the drivers don't need 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).

Signed-off-by: Igor Torrente <igormtorre...@gmail.com>
---
 drivers/gpu/drm/drm_atomic_helper.c   | 39 +++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_writeback.c |  9 +++----
 include/drm/drm_atomic_helper.h       |  3 +++
 3 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c 
b/drivers/gpu/drm/drm_atomic_helper.c
index 9603193d2fa1..2052e18fa64c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -776,6 +776,45 @@ 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
diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c 
b/drivers/gpu/drm/vkms/vkms_writeback.c
index 8694227f555f..746cb0abc6ec 100644
--- a/drivers/gpu/drm/vkms/vkms_writeback.c
+++ b/drivers/gpu/drm/vkms/vkms_writeback.c
@@ -30,6 +30,7 @@ static int vkms_wb_encoder_atomic_check(struct drm_encoder 
*encoder,
 {
        struct drm_framebuffer *fb;
        const struct drm_display_mode *mode = &crtc_state->mode;
+       int ret;
 
        if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
                return 0;
@@ -41,11 +42,9 @@ static int vkms_wb_encoder_atomic_check(struct drm_encoder 
*encoder,
                return -EINVAL;
        }
 
-       if (fb->format->format != vkms_wb_formats[0]) {
-               DRM_DEBUG_KMS("Invalid pixel format %p4cc\n",
-                             &fb->format->format);
-               return -EINVAL;
-       }
+       ret = drm_atomic_helper_check_wb_encoder_state(encoder, conn_state);
+       if (ret < 0)
+               return ret;
 
        return 0;
 }
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 4045e2507e11..3fbf695da60f 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -40,6 +40,9 @@ struct drm_private_state;
 
 int drm_atomic_helper_check_modeset(struct drm_device *dev,
                                struct drm_atomic_state *state);
+int
+drm_atomic_helper_check_wb_encoder_state(struct drm_encoder *encoder,
+                                        struct drm_connector_state 
*conn_state);
 int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state,
                                        const struct drm_crtc_state *crtc_state,
                                        int min_scale,
-- 
2.30.2