| Message ID | 1694069533-7832-3-git-send-email-spujar@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Fix redundant PLLA update | expand |
On Thu, Sep 07, 2023 at 12:22:13PM +0530, Sameer Pujar wrote: > Fixes: 202e2f774543 ("ASoC: tegra: Add audio graph based card driver") > Cc: stable@vger.kernel.org This is just a performance improvement rather than a correctness fix as far as I can tell?
On 07-09-2023 17:21, Mark Brown wrote: > On Thu, Sep 07, 2023 at 12:22:13PM +0530, Sameer Pujar wrote: > >> Fixes: 202e2f774543 ("ASoC: tegra: Add audio graph based card driver") >> Cc: stable@vger.kernel.org > This is just a performance improvement rather than a correctness fix as > far as I can tell? This was supposed to be a performance improvement. However this is found to be resolving a DMIC clock discrepancy and suspect is it happens because of back to back quick PLLA updates. Thought it would be safer to have this fix in stable releases. May be I should mention these points to justify the 'Fixes' and 'stable' tag?
On Thu, Sep 07, 2023 at 07:51:13PM +0530, Sameer Pujar wrote: > On 07-09-2023 17:21, Mark Brown wrote: > > On Thu, Sep 07, 2023 at 12:22:13PM +0530, Sameer Pujar wrote: > > > Fixes: 202e2f774543 ("ASoC: tegra: Add audio graph based card driver") > > > Cc: stable@vger.kernel.org > > This is just a performance improvement rather than a correctness fix as > > far as I can tell? > This was supposed to be a performance improvement. However this is found to > be resolving a DMIC clock discrepancy and suspect is it happens because of > back to back quick PLLA updates. Thought it would be safer to have this fix > in stable releases. May be I should mention these points to justify the > 'Fixes' and 'stable' tag? Yes, please - that does make sense as a fix.
diff --git a/sound/soc/tegra/tegra_audio_graph_card.c b/sound/soc/tegra/tegra_audio_graph_card.c index 1f2c5018bf5a..4737e776d383 100644 --- a/sound/soc/tegra/tegra_audio_graph_card.c +++ b/sound/soc/tegra/tegra_audio_graph_card.c @@ -10,6 +10,7 @@ #include <linux/platform_device.h> #include <sound/graph_card.h> #include <sound/pcm_params.h> +#include <sound/soc-dai.h> #define MAX_PLLA_OUT0_DIV 128 @@ -44,6 +45,21 @@ struct tegra_audio_cdata { unsigned int plla_out0_rates[NUM_RATE_TYPE]; }; +static bool need_clk_update(struct snd_soc_dai *dai) +{ + if (snd_soc_dai_is_dummy(dai) || + !dai->driver->ops || + !dai->driver->name) + return false; + + if (strstr(dai->driver->name, "I2S") || + strstr(dai->driver->name, "DMIC") || + strstr(dai->driver->name, "DSPK")) + return true; + + return false; +} + /* Setup PLL clock as per the given sample rate */ static int tegra_audio_graph_update_pll(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params) @@ -140,19 +156,7 @@ static int tegra_audio_graph_hw_params(struct snd_pcm_substream *substream, struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0); int err; - /* - * This gets called for each DAI link (FE or BE) when DPCM is used. - * We may not want to update PLLA rate for each call. So PLLA update - * must be restricted to external I/O links (I2S, DMIC or DSPK) since - * they actually depend on it. I/O modules update their clocks in - * hw_param() of their respective component driver and PLLA rate - * update here helps them to derive appropriate rates. - * - * TODO: When more HW accelerators get added (like sample rate - * converter, volume gain controller etc., which don't really - * depend on PLLA) we need a better way to filter here. - */ - if (cpu_dai->driver->ops && rtd->dai_link->no_pcm) { + if (need_clk_update(cpu_dai)) { err = tegra_audio_graph_update_pll(substream, params); if (err) return err;
Tegra audio graph card has many DAI links which connects internal AHUB modules and external audio codecs. Since these are DPCM links, hw_params() call in the machine driver happens for each connected BE link and PLLA is updated every time. This is not really needed for all links as only I/O link DAIs derive respective clocks from PLLA_OUT0 and thus from PLLA. Hence add checks to limit the clock updates to DAIs over I/O links. Fixes: 202e2f774543 ("ASoC: tegra: Add audio graph based card driver") Cc: stable@vger.kernel.org Signed-off-by: Sameer Pujar <spujar@nvidia.com> --- sound/soc/tegra/tegra_audio_graph_card.c | 30 ++++++++++++++---------- 1 file changed, 17 insertions(+), 13 deletions(-)