Messages in this thread | | | From | Ryan Lee <> | Subject | RE: [PATCH] ASoC: max98373: Added max98373_reset for stable amp reset | Date | Tue, 27 Nov 2018 17:46:04 +0000 |
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>-----Original Message----- >From: Grant Grundler <grundler@chromium.org> >Sent: Monday, November 26, 2018 6:28 PM >To: Grant Grundler <grundler@chromium.org> >Cc: Ryan Lee <RyanS.Lee@maximintegrated.com>; Liam Girdwood ><lgirdwood@gmail.com>; broonie@kernel.org; perex@perex.cz; >tiwai@suse.com; Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>; >Benson Leung <bleung@chromium.org>; alsa-devel@alsa-project.org; LKML ><linux-kernel@vger.kernel.org> >Subject: Re: [PATCH] ASoC: max98373: Added max98373_reset for stable amp >reset > >EXTERNAL EMAIL > > > >I just realized I had one more question... > >On Mon, Nov 26, 2018 at 6:24 PM Grant Grundler <grundler@chromium.org> >wrote: >> >> Hi Ryan! >> >> Just some questions inline - in general I like the reset function. >> >> On Mon, Nov 26, 2018 at 10:46 AM Ryan Lee ><RyanS.Lee@maximintegrated.com> wrote: >> > >> > Signed-off-by: Ryan Lee <ryans.lee@maximintegrated.com> >> > --- >> > Changes : Created max98373_reset function to minimize code duplication. >> > Changed regmap_write to regmap_update_bits. Other bits except >LSB need to be masked. >> > Added reset verification step to make sure software reset is >completed well. Software reset is done in 10ms in normal case. >> > Revision ID is available when the amp is in the idle state which means >software reset is completed. > >Why not poll the RevID register a few times until it gives a value? > >Then structure the code to try reset twice (maybe three times). >This would avoid the unusual "sleep time after reset is increased" code. Let me fix unusual things here. Thanks for the comment.
> >cheers, >grant > >> > Software reset will be performed maximum 3 times to avoid amp >reset failure. Generally it is done in the first trial. >> > sleep time after software reset is increased + 30ms for every retrial. >Maximum possible msleep time is 100 ms (initial 10 ms + 30 ms * 3 times). >> >> Why is the sleep time increased after each SW reset? >> What is the failure case that you've seen which would benefit from this? >> >> > >> > sound/soc/codecs/max98373.c | 41 >> > +++++++++++++++++++++++++++++++++++------ >> > 1 file changed, 35 insertions(+), 6 deletions(-) >> > >> > diff --git a/sound/soc/codecs/max98373.c >> > b/sound/soc/codecs/max98373.c index a09d013..55af7f02 100644 >> > --- a/sound/soc/codecs/max98373.c >> > +++ b/sound/soc/codecs/max98373.c >> > @@ -724,14 +724,45 @@ static struct snd_soc_dai_driver max98373_dai[] >= { >> > } >> > }; >> > >> > +static void max98373_reset(struct max98373_priv *max98373, struct >> > +device *dev) { >> > + int ret, reg, count, delay; >> > + >> > + count = 0; >> > + while (true) { >> > + /* Software Reset */ >> > + ret = regmap_update_bits(max98373->regmap, >> > + MAX98373_R2000_SW_RESET, >> > + MAX98373_SOFT_RESET, >> > + MAX98373_SOFT_RESET); >> > + if (ret) >> > + dev_err(dev, "Reset command failed. >> > + (ret:%d)\n", ret); >> > + >> > + delay = 10000 + (count * 30000); >> > + usleep_range(delay, delay + 1000); >> > + >> > + /* Software Reset Verification */ >> > + ret = regmap_read(max98373->regmap, >> > + MAX98373_R21FF_REV_ID, ®); >> > + if (!ret) { >> > + dev_info(dev, "Reset completed (retry:%d)\n", count); >> > + break; >> >> Instead of break, can the code return here? >> "break" implies something else will happen after the while loop exits >> - there isn't. >> >> > + } >> > + >> > + if (++count > 3) { >> > + dev_err(dev, "Reset failed. (ret:%d)\n", ret); >> > + break; >> > + } >> > + usleep_range(10000, 11000); >> >> Why is there a second delay after reading MAX98373_R21FF_REV_ID? >> Is this really necessary? >> >> If the second usleep_range() isn't needed, it would be better/clearer >> to make code loop on "while (count < 4)". And then outside the while >> loop, use dev_err() to share what the failure was. >> >> > + } >> > +} >> > + >> > static int max98373_probe(struct snd_soc_component *component) { >> > struct max98373_priv *max98373 = >> > snd_soc_component_get_drvdata(component); >> > >> > /* Software Reset */ >> > - regmap_write(max98373->regmap, >> > - MAX98373_R2000_SW_RESET, MAX98373_SOFT_RESET); >> > - usleep_range(10000, 11000); >> > + max98373_reset(max98373, component->dev); >> > >> > /* IV default slot configuration */ >> > regmap_write(max98373->regmap, @@ -818,9 +849,7 @@ static >> > int max98373_resume(struct device *dev) { >> > struct max98373_priv *max98373 = dev_get_drvdata(dev); >> > >> > - regmap_write(max98373->regmap, >> > - MAX98373_R2000_SW_RESET, MAX98373_SOFT_RESET); >> > - usleep_range(10000, 11000); >> > + max98373_reset(max98373, dev); >> > regcache_cache_only(max98373->regmap, false); >> > regcache_sync(max98373->regmap); >> > return 0; >> > -- >> > 2.7.4 >> > >> >> cheers, >> grant
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