[PATCH RFT v2 0/5] drm: Add and use drm_fb_dma_get_gem_clipped_addr() helper

[Chen-Yu Tsai]

Hi,

This is v2 of my drm_fb_dma_get_gem_clipped_addr() series.

Changes since v1:
- Add and use new drm_framebuffer_get_block_offset() helper (Thomas)


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.)

While at it, also pull out the offset calculation of drm_fb_dma_get_gem_addr()
into a separate helper in drm_framebuffer.[ch], thereby separating
responsibilities.

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. Two other drivers were also touched.


Patch 1 adds a new helper to return the byte offset into a framebuffer
for the start of the pixel block of the given pixel coordinates.

Patch 2 adds the new helper to return the buffer address based on
clipped coordinates.

Patch 3 switches the sun4i driver to the new helper, and fixes the
luma plane buffer address offset for subsampled YUV formats.

Patch 4 converts the imx/dc driver to use the new helper. This fixes a
mismatch between the programmed coordinates and the buffer address.

Patch 5 replaces the open coded buffer address calculation in the
imx/dcss driver with the new helper. Existing behavior, which might be
wrong, is preserved.


Please help test. The series is only compile tested on my end. The sun4i
changes should revert its behavior to before the drm_fb_dma_get_gem_addr()
was adopted. The imx/dcss changes should not have any behavioral
difference.


Thanks
ChenYu

Chen-Yu Tsai (5):
  drm: Split framebuffer pixel offset calculation from
    drm_fb_dma_get_gem_addr()
  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    | 61 ++++++++++++++------------
 drivers/gpu/drm/drm_framebuffer.c      | 45 +++++++++++++++++++
 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 ++
 include/drm/drm_framebuffer.h          |  3 ++
 8 files changed, 118 insertions(+), 51 deletions(-)

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2.55.0.1032.g73a4cd73de-goog