[PATCH 1/5] drm/modes: Indicate CEA-861 CE modes to user-space

Yussuf Khalil
2020-04-13T21:52:16Z

Add a new flag to mark modes that are considered a CE mode according to the
CEA-861 specification. Modes without this flag are implicitly considered to
be IT modes.

User-space applications may use this flag to determine possible
implications of using a CE mode (e.g., limited RGB range).

There is no use for this flag inside the kernel, so we set it only when
communicating a mode to user-space.

Signed-off-by: Yussuf Khalil <dev@pp3345.net>
---
drivers/gpu/drm/drm_modes.c | 14 ++++++++++++++
include/uapi/drm/drm_mode.h | 2 ++
2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index d4d64518e11b..0d8a032f437d 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1973,6 +1973,14 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out,
break;
}

+ if (drm_match_cea_mode(in) > 1) {
+ /*
+ * All modes in CTA-861-G Table 1 are CE modes, except 640x480p
+ * (VIC 1).
+ */
+ out->flags |= DRM_MODE_FLAG_CEA_861_CE_MODE;
+ }
+
strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
out->name[DRM_DISPLAY_MODE_LEN-1] = 0;
}
@@ -2045,6 +2053,12 @@ int drm_mode_convert_umode(struct drm_device *dev,
return -EINVAL;
}

+ /*
+ * The CEA-861 CE mode flag is purely informational and intended for
+ * userspace only.
+ */
+ out->flags &= ~DRM_MODE_FLAG_CEA_861_CE_MODE;
+
out->status = drm_mode_validate_driver(dev, out);
if (out->status != MODE_OK)
return -EINVAL;
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 735c8cfdaaa1..5e78b350b2e2 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -124,6 +124,8 @@ extern "C" {
#define DRM_MODE_FLAG_PIC_AR_256_135 \
(DRM_MODE_PICTURE_ASPECT_256_135<<19)

+#define DRM_MODE_FLAG_CEA_861_CE_MODE (1<<23)
+
#define DRM_MODE_FLAG_ALL (DRM_MODE_FLAG_PHSYNC | \
DRM_MODE_FLAG_NHSYNC | \
DRM_MODE_FLAG_PVSYNC | \
--
2.26.0