Måns Rullgård <mans@xxxxxxxxx> writes: > Frank Oltmanns <frank@xxxxxxxxxxxx> writes: > >> Hi Måns, >> >> 21.05.2024 15:43:10 Måns Rullgård <mans@xxxxxxxxx>: >> >>> Frank Oltmanns <frank@xxxxxxxxxxxx> writes: >>> >>>> The Allwinner SoC's typically have an upper and lower limit for their >>>> clocks' rates. Up until now, support for that has been implemented >>>> separately for each clock type. >>>> >>>> Implement that functionality in the sunxi-ng's common part making use of >>>> the CCF rate liming capabilities, so that it is available for all clock >>>> types. >>>> >>>> Suggested-by: Maxime Ripard <mripard@xxxxxxxxxx> >>>> Signed-off-by: Frank Oltmanns <frank@xxxxxxxxxxxx> >>>> Cc: stable@xxxxxxxxxxxxxxx >>>> --- >>>> drivers/clk/sunxi-ng/ccu_common.c | 19 +++++++++++++++++++ >>>> drivers/clk/sunxi-ng/ccu_common.h | 3 +++ >>>> 2 files changed, 22 insertions(+) >>> >>> This just landed in 6.6 stable, and it broke HDMI output on an A20 based >>> device, the clocks ending up all wrong as seen in this diff of >>> /sys/kernel/debug/clk/clk_summary: [...] >>> Reverting this commit makes it work again. >> >> Thank you for your detailed report! >> >> I've had a first look at hdmi-tmds and hdmi-ddc, and neither seems to >> be calling ccu_is_better_rate() in their determine_rate() >> functions. Their parents have the exact same rates in your diff, so, >> my current working assumption is that they can't be the cause either. >> >> I'll have a more detailed look over the weekend. Until then, if anyone >> has some ideas where I should have a look next, please share your >> thoughts. > > In case it's relevant, this system doesn't use the HDMI DDC, the > physical DDC pins being connected to a different I2C adapter for > various reasons. > > From the clk_summary diff, I see a few things: > > 1. hdmi-tmds has changed parent from pll-video1-2x to pll-video0-2x. > 2. The ratio of hdmi-tmds to its parent has changed from 1/8 to 1. > 3. The resulting rate bears no relation to the pixel clock from EDID. > > I tried kernel 6.9.1 as well, and that doesn't work either. I'll keep > digging and try to narrow it down. It turns out HDMI output is broken in v6.9 for a different reason. However, this commit (b914ec33b391 clk: sunxi-ng: common: Support minimum and maximum rate) requires two others as well in order not to break things on the A20: cedb7dd193f6 drm/sun4i: hdmi: Convert encoder to atomic 9ca6bc246035 drm/sun4i: hdmi: Move mode_set into enable With those two (the second depends on the first) cherry-picked on top of v6.6.31, the HDMI output is working again. Likewise on v6.8.10. -- Måns Rullgård
