On Tue, Mar 21, 2017 at 2:52 PM, Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, Mar 21, 2017 at 12:09:36PM +0200, Daniel Baluta wrote: >> WM8960 derives bit clock from sysclock using BCLKDIV[3:0] of R8 >> clocking register (See WM8960 datasheet, page 71). >> >> There are use cases, like this: >> aplay -Dhw:0,0 -r 48000 -c 1 -f S20_3LE -t raw audio48k20b_3LE1c.pcm >> >> where no BCLKDIV applied to sysclock can give us the exact requested >> bitclk, so driver fails to configure clocking and aplay fails to run. >> >> Fix this by relaxing bitclk computation, so that when no exact value >> can be derived from sysclk pick the closest value greater than >> expected bitclk. >> >> Suggested-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx> >> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxx> >> --- >> Changes since v1: >> * use a marker to check if a match is found >> * didn't removed PLL as Charles suggested because there is >> a special PLL mode which explictly uses PLL. We could start >> a discussion on not using PLL when deriving bitclk, but this >> is to be done in another patch. >> > > Could you elaborate on this a little more am I not sure I follow > 100%? There is a mode which explictly requires the PLL to be used > (WM8960_SYSCLK_PLL) but in that case your wm8960_configure_sysclk > code will not be called so I don't see what is causing that to have > an effect on this patch? My doubt is, what happens if wm8960_configure_clocking is called with wm8960->clk_id = WM8960_SYSCLK_PLL and we remove the PLL as suggested. Is this possible even possible? Anyhow, I noticed that so far wm8960->clk_id is never set to WM8960_SYSCLK_PLL :). So, my proposal is to merge this patch which improves the existing code and deal with PLL fallback in a separate patch later. I am afraid of touching things which I don't understand how they work :D. thanks, Daniel. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
