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 at st.com> 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 at st.com> >>> --- >>> 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 at chromium.org> >> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
