On 18/06/2019 19:23, Jernej Škrabec wrote: > Hi! > > Dne torek, 18. junij 2019 ob 01:55:58 CEST je Douglas Anderson napisal(a): >> Let's add some better support for HDMI audio to dw_hdmi. >> Specifically: >> >> 1. For 44.1 kHz audio the old code made the assumption that an N of >> 6272 was right most of the time. That wasn't true and the new table >> should give better 44.1 kHz audio for many more rates. >> >> 2. The new table has values from the HDMI spec for 297 MHz and 594 >> MHz. >> >> 3. There is now code to try to come up with a more idea N/CTS for >> clock rates that aren't in the table. This code is a bit slow because >> it iterates over every possible value of N and picks the best one, but >> it should make a good fallback. >> >> 4. The new code allows for platforms that know they make a clock rate >> slightly differently to pick different N/CTS values. For instance on >> rk3288 we can make 25,176,471 Hz instead of 25,174,825.1748... Hz >> (25.2 MHz / 1.001). A future patch to the rk3288 platform code could >> enable support for this clock rate and specify the N/CTS that would be >> ideal. >> >> NOTE: the oddest part of this patch comes about because computing the >> ideal N/CTS means knowing the _exact_ clock rate, not a rounded >> version of it. The drm framework makes this harder by rounding rates >> to kHz, but even if it didn't there might be cases where the ideal >> rate could only be calculated if we knew the real (non-integral) rate. >> This means that in cases where we know (or believe) that the true rate >> is something other than the rate we are told by drm. >> >> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > > Which bus is used for audio transfer on your device? If it is I2S, which is > commonly used, then please be aware of this patch: > https://lists.freedesktop.org/archives/dri-devel/2019-June/221539.html > > It avoids exact N/CTS calculation by enabling auto detection. It is well > tested on multiple SoCs from Allwinner, Amlogic and Rockchip. > > Best regards, > Jernej > > Hi Douglas, Thanks for your work ! If you could rebase on top of https://lists.freedesktop.org/archives/dri-devel/2019-June/221539.html so we can make use of your extended N table with automatic CTS HW calculation, it would be great ! Finally could you add the plat_data tmds table as a separate patch to simplify review ? Thanks, Neil _______________________________________________ Linux-rockchip mailing list Linux-rockchip@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-rockchip
