[v4,0/4] drm: lcdif: Improve YUV support

Message

Laurent Pinchart Sept. 30, 2022, 8:39 a.m. UTC

Hello,

This small patch series improves YUV support in the i.MX8MP LCDIF
driver. After patches 1/4 and 2/4 that fix tiny cosmetic issues, patch
3/4 fixes YUV quantization range for the RGB to YUV conversion. Patch
4/4 addresses the other direction and adds support for YUV planes.

Compared to v3, review comments have been taken into account, and the
series has been rebased on top of drm-misc-next.

Compared to v2, review comments have been taken into account, and the
YUV to RGB coefficients in patch 4/4 have been fixed (they were
blatantly wrong due to a stupid mistake).

Please see individual patches for details and detailed changelogs.

The series has been tested on a Polyhex Debix board with the currently
out-of-tree HDMI encoder support patches developed by Lucas Stach, with
the kmstest and the libcamera 'cam' applications.

There is a know issue with the way the driver programs the format and
pitch, which produces incorrect output when testing YUV formats with the
legacy (non-atomic) KMS API, in particular with the modetest
application. The framebuffer is accessed from the plane state in
function called from the .atomic_enable() handler, which in some
circumstances results in the format and/or pitch of the old frame buffer
being used. This issue preexists, and can be triggered by selecting a
different RGB format with modetest (XR15 for instance). It should be
fixed separately, and I wouldn't consider it as a blocker for this
series as YUV formats can already be used correctly when using the KMS
atomic API.

Kieran Bingham (1):
  drm: lcdif: Add support for YUV planes

Laurent Pinchart (3):
  drm: lcdif: Fix indentation in lcdif_regs.h
  drm: lcdif: Don't use BIT() for multi-bit register fields
  drm: lcdif: Switch to limited range for RGB to YUV conversion

 drivers/gpu/drm/mxsfb/lcdif_kms.c  | 239 ++++++++++++++++++++++++++---
 drivers/gpu/drm/mxsfb/lcdif_regs.h |  37 +++--
 2 files changed, 236 insertions(+), 40 deletions(-)


base-commit: c9b48b91e2fbb74fb981aa616a6ef3c78194077f