Messages in this thread | | | Subject | Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock | From | Sameer Pujar <> | Date | Wed, 10 Mar 2021 20:20:28 +0530 |
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On 3/10/2021 4:00 AM, Michael Walle wrote: > Am 2021-03-09 17:27, schrieb Sameer Pujar: >> On 3/9/2021 8:11 PM, Michael Walle wrote: >>>> If "clocks = <&xxx>" is specified from the CPU or Codec component >>>> device node, the clock is not getting enabled. Thus audio playback >>>> or capture fails. >>>> >>>> Fix this by populating "simple_dai->clk" field when clocks property >>>> is specified from device node as well. Also tidy up by re-organising >>>> conditional statements of parsing logic. >>>> >>>> Fixes: bb6fc620c2ed ("ASoC: simple-card-utils: add >>>> asoc_simple_card_parse_clk()") >>>> Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> >>>> Signed-off-by: Sameer Pujar <spujar@nvidia.com> >>> >>> This actually breaks sound on my board >>> (arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts). >>> The codec on this board (wm8904) has a fixed clock input (only >>> distinct >>> frequencies are supported) and uses the FLL of the codec to generate >>> the >>> desired sample rate. >>> >>> It seems that after this patch the clock rate of the codecs clock >>> (rather >>> than the FLL) is tried to be changed. Which fails, because it doesn't >>> support arbitrary frequencies. >> >> Yes, after the given change the clock will be updated if "*mclk-fs" >> property is specified. >> >> DT you mentioned has property "simple-audio-card,mclk-fs = <256>", >> which means you need a clock that is a function of sample rate. But as >> per above you want a fixed clock for MCLK. I think if you drop this >> property, the clock updates won't happen. Earlier for your case, this >> property was not used at all because the clock handle was not >> populated. > > You mean to drop the mclk-fs property? I can't do that because I > actually need a frequency of 256 * sample rate. But that doesn't > necessarily need to be the MCLK, because the codec itself has a > FLL/PLL which can be used to generate any frequency for a given > MCLK. So that is a valid scenario. See also commit 13409d27cb39 > ("ASoC: wm8904: configure sysclk/FLL automatically"). >
If I read this correctly below is the configuration you need, SoC -> MCLK(fixed rate) -> PLL(wm8904) -> PLL output (256 * fs) -> sysclk
From the doc simple-card.txt, "simple-audio-card,mclk-fs" is a scaling factor for MCLK and hence I am not sure if it is correct to have "*mclk-fs" property when MCLK is fixed. In simple cases, codec sysclk direclty depends on MCLK and set_sysclk() callback helps. Your case requires PLL configuration and set_pll() may be a better alternative. However simple-card does not offer this yet. But even if this is added, there should be a way to suggest PLL output requirement as a function of sample rate.
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