Skip to content
Snippets Groups Projects
Forked from drm / msm
Loading
Marijn Suijten's avatar
Marijn Suijten authored
According to the comment this DPU register contains the bits per pixel
as a 6.4 fractional value, conveniently matching the contents of
bits_per_pixel in struct drm_dsc_config which also uses 4 fractional
bits.  However, the downstream source this implementation was
copy-pasted from has its bpp field stored _without_ fractional part.

This makes the entire convoluted math obsolete as it is impossible to
pull those 4 fractional bits out of thin air, by somehow trying to reuse
the lowest 2 bits of a non-fractional bpp (lsb = bpp % 4??).

The rest of the code merely attempts to keep the integer part a multiple
of 4, which is rendered useless thanks to data |= dsc->bits_per_pixel <<
12; already filling up those bits anyway (but not on downstream).

Fixes: c110cfd1 ("drm/msm/disp/dpu1: Add support for DSC")
Signed-off-by: default avatarMarijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: default avatarAbhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: default avatarVinod Koul <vkoul@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/508946/
Link: https://lore.kernel.org/r/20221026182824.876933-10-marijn.suijten@somainline.org


Signed-off-by: default avatarDmitry Baryshkov <dmitry.baryshkov@linaro.org>
d3c1a866
History
Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.