mbox series

[0/4] drm: Add and use drm_fb_dma_get_gem_clipped_addr() helper

Message ID 20260908090745.1089143-1-wenst@chromium.org (mailing list archive)
Headers
Series drm: Add and use drm_fb_dma_get_gem_clipped_addr() helper |

Message

Chen-Yu Tsai Sept. 8, 2026, 9:07 a.m. UTC 
Hi,

This series adds a helper to retrieve the buffer starting address of a
"clipped" framebuffer. This contrasts with drm_fb_dma_get_gem_addr(),
which gives the address of the full buffer.

Some drivers program their hardware with clipped dimensions, so they
should be using the clipped buffer address as well, unless the hardware
can advance the scanout directly. (Side note: many drivers still use
the non-clipped dimensions.)

The sun4i driver was recently incorrectly converted to use the unclipped
drm_fb_dma_get_gem_addr() helper. This broke offsets into subsampled
pixel groups, but also exposed the mismatch between the dimensions used
vs the buffer address.


Patch 1 adds the new helper to return the buffer address based on
clipped coordinates.

Patch 2 switches the sun4i driver to the new helper, and fixes the
luma plane buffer address offset for subsampled YUV formats.

Patch 3 converts the imx/dc driver to use the new helper. This fixes a
mismatch between the programmed coordinates and the buffer address.

Patch 4 replaces the open coded buffer address calculation in the
imx/dcss driver with the new helper.


Please have a look.


Thanks
ChenYu


Chen-Yu Tsai (4):
  drm/fb-dma-helper: Add drm_fb_dma_get_gem_clipped_addr()
  drm/sun4i: layers: Fix VI buffer address for clipped offsets
  drm/imx/dc: plane: Switch to drm_fb_dma_get_gem_clipped_addr()
  drm/imx/dcss: plane: Switch to drm_fb_dma_get_gem_clipped_addr()

 drivers/gpu/drm/drm_fb_dma_helper.c    | 63 +++++++++++++++++++-------
 drivers/gpu/drm/imx/dc/dc-plane.c      |  4 +-
 drivers/gpu/drm/imx/dcss/dcss-plane.c  | 34 ++++++--------
 drivers/gpu/drm/sun4i/sun8i_ui_layer.c |  2 +-
 drivers/gpu/drm/sun4i/sun8i_vi_layer.c | 16 ++++++-
 include/drm/drm_fb_dma_helper.h        |  4 ++
 6 files changed, 83 insertions(+), 40 deletions(-)