From: Grant Grundler <grundler@chromium.org>
To: Grant Grundler <grundler@chromium.org>
Cc: 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
Date: Mon, 26 Nov 2018 18:27:40 -0800 [thread overview]
Message-ID: <CANEJEGs+ou+YyB503fyX9sqSzbp-EpykGo7OXgCNV0cW7RA0vA@mail.gmail.com> (raw)
In-Reply-To: <CANEJEGu30oPGRjeK2Sp1dUj4CuFjZeZ9+-2DRwhvmMLNex3p7A@mail.gmail.com>
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.
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
next prev parent reply other threads:[~2018-11-27 2:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 18:46 [PATCH] ASoC: max98373: Added max98373_reset for stable amp reset Ryan Lee
2018-11-27 2:24 ` Grant Grundler
2018-11-27 2:27 ` Grant Grundler [this message]
2018-11-27 17:46 ` Ryan Lee
2018-11-27 17:44 ` Ryan Lee
2018-11-27 11:50 ` Mark Brown
2018-11-27 17:53 ` Ryan Lee
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CANEJEGs+ou+YyB503fyX9sqSzbp-EpykGo7OXgCNV0cW7RA0vA@mail.gmail.com \
--to=grundler@chromium.org \
--cc=RyanS.Lee@maximintegrated.com \
--cc=alsa-devel@alsa-project.org \
--cc=bleung@chromium.org \
--cc=broonie@kernel.org \
--cc=kuninori.morimoto.gx@renesas.com \
--cc=lgirdwood@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=perex@perex.cz \
--cc=tiwai@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).