On 01/26/2018 03:24 PM, Philippe CORNU wrote:
Hi Brian,
And a big thanks for your Tested-by
On 01/25/2018 11:47 PM, Brian Norris wrote:
On Thu, Jan 25, 2018 at 7:55 AM, Philippe Cornu <philippe.cornu@xxxxxx> wrote:
The "adjusted_mode" clock value (ie the real pixel clock) is more
accurate than "mode" clock value (ie the panel/bridge requested
clock value). It offers a better preciseness for timing
computations and allows to reduce the extra dsi bandwidth in
burst mode (from ~20% to ~10-12%, hw platform dependant).
Signed-off-by: Philippe Cornu <philippe.cornu@xxxxxx>
---
Note: This patch replaces "drm/bridge/synopsys: dsi: add optional pixel clock"
These two appear to be the same for my cases, but at least nothing breaks:
In drivers/gpu/drm/rockchip/rockchip_drm_vop.c function
vop_crtc_mode_fixup(), the adjusted_mode->clock (ie. vop px clk output =
dw dsi px clk input) is updated according to rockchip hw pll/dividers...
So you "may" have a different value in adjusted_mode->clock compare to
mode->clock. Maybe there is no difference for the panel you are using
because its px clock matches perfectly with rockchip hw pll/dividers...
or has been set to match with ;-)
I did a similar patch (see [1]) and it works "fine" on stm, the only
difference with the rockchip vop is that clk_round_rate() returns odd
values on stm so I used set/get_rate instead.
So now, both rockchip & stm crtc have an "adjusted_mode->clock" so it
makes sense to use it in dw dsi :)
Could you get the patch [1] queued on drm-misc-next? I can queue this patch
after it.
Thanks,
Archit
Philippe :-)
[1] https://patchwork.freedesktop.org/patch/200720/
"[PATCH] drm/stm: ltdc: use crtc_mode_fixup to update adjusted_mode clock"
Tested-by: Brian Norris <briannorris@xxxxxxxxxxxx>
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