377569f82e
Neither vtotal nor drm_mode_vrefresh contain a value that is premultiplied by 100 making the x100 variable name incorrect and resulting in vclks_line to become 100 times larger than it is supposed to be. The hardware counts 100 clockticks too many before tearcheck, leading to severe panel issues on at least the Sony Xperia lineup. This is likely an artifact from the original MDSS DSI panel driver where the calculation [1] corrected for a premultiplied reference framerate by 100 [2]. It does not appear that the above values were ever premultiplied in the history of the DRM MDP5 driver. With this change applied the value written to the SYNC_CONFIG_VSYNC register is now identical to downstream kernels. [1]: https://source.codeaurora.org/quic/la/kernel/msm-3.18/tree/drivers/video/msm/mdss/mdss_mdp_intf_cmd.c?h=LA.UM.8.6.c26-02400-89xx.0#n288 [2]: https://source.codeaurora.org/quic/la/kernel/msm-3.18/tree/drivers/video/msm/mdss/mdss_dsi_panel.c?h=LA.UM.8.6.c26-02400-89xx.0#n1648 Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org> Link: https://lore.kernel.org/r/20210406214726.131534-3-marijn.suijten@somainline.org Signed-off-by: Rob Clark <robdclark@chromium.org>
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.