[PATCH v2 2/2] drm: meson: venc: cvbs: fix CVBS mode matching

From: Martin Blumenstingl
Date: Sun Dec 08 2019 - 12:19:11 EST

With commit 222ec1618c3ace ("drm: Add aspect ratio parsing in DRM
layer") the drm core started honoring the picture_aspect_ratio field
when comparing two drm_display_modes. Prior to that it was ignored.
When the CVBS encoder driver was initially submitted there was no aspect
ratio check.

Switch from drm_mode_equal() to drm_mode_match() without
DRM_MODE_MATCH_ASPECT_RATIO to fix "kmscube" and X.org output using the
CVBS connector. When (for example) kmscube sets the output mode when
using the CVBS connector it passes HDMI_PICTURE_ASPECT_NONE, making the
drm_mode_equal() fail as it include the aspect ratio.

Prior to this patch kmscube reported:
failed to set mode: Invalid argument

The CVBS mode checking in the sun4i (drivers/gpu/drm/sun4i/sun4i_tv.c
sun4i_tv_mode_to_drm_mode) and ZTE (drivers/gpu/drm/zte/zx_tvenc.c
tvenc_mode_{pal,ntsc}) drivers don't set the "picture_aspect_ratio" at
all. The Meson VPU driver does not rely on the aspect ratio for the CVBS
output so we can safely decouple it from the hdmi_picture_aspect

Fixes: 222ec1618c3ace ("drm: Add aspect ratio parsing in DRM layer")
Fixes: bbbe775ec5b5da ("drm: Add support for Amlogic Meson Graphic Controller")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
drivers/gpu/drm/meson/meson_venc_cvbs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/meson/meson_venc_cvbs.c b/drivers/gpu/drm/meson/meson_venc_cvbs.c
index 6b8a074e4ff4..1bd6b6d15ffb 100644
--- a/drivers/gpu/drm/meson/meson_venc_cvbs.c
+++ b/drivers/gpu/drm/meson/meson_venc_cvbs.c
@@ -72,7 +72,11 @@ meson_cvbs_get_mode(const struct drm_display_mode *req_mode)
for (i = 0; i < MESON_CVBS_MODES_COUNT; ++i) {
struct meson_cvbs_mode *meson_mode = &meson_cvbs_modes[i];

- if (drm_mode_equal(req_mode, &meson_mode->mode))
+ if (drm_mode_match(req_mode, &meson_mode->mode,
return meson_mode;