From: Viorel Suman <viorel.suman@nxp.com>
To: Mark Brown <broonie@kernel.org>
Cc: "Viorel Suman (OSS)" <viorel.suman@oss.nxp.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
Philipp Zabel <p.zabel@pengutronix.de>,
Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
"S.j. Wang" <shengjiu.wang@nxp.com>,
Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
Peter Ujfalusi <peter.ujfalusi@ti.com>,
Lee Jones <lee.jones@linaro.org>,
"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFC PATCH] ASoC: ak4458: use reset control instead of reset gpio
Date: Thu, 19 Nov 2020 16:22:42 +0000 [thread overview]
Message-ID: <VI1PR0401MB22726479D60E9B603A6848BC92E00@VI1PR0401MB2272.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20201118115500.GB4827@sirena.org.uk>
> On Tue, Nov 17, 2020 at 06:17:36PM +0000, Viorel Suman wrote:
> > > On Tue, Nov 17, 2020 at 12:20:36AM +0200, Viorel Suman (OSS) wrote:
>
> > > One thing I'm not clear on is if there's some way to ensure that we
> > > don't have different instances of the device resetting each other without
> them noticing?
> > > Shouldn't be an issue in practice for the use here.
>
> > The way to ensure that we don't have different instances of the device
> > resetting each other is to rely on the way the "shared" reset is handled by
> reset API:
> > ==========
> > + ak4458->reset = devm_reset_control_get_optional_shared(ak4458-
> >dev, NULL);
> > + if (IS_ERR(ak4458->reset))
> > + return PTR_ERR(ak4458->reset);
> > ==========
>
> Flip side of that then, how do we know when a reset has actually happened?
I don't see how this can be achieved - I'd imagine some "shared" reset
framework notification mechanism calling back all "listeners" in the moment
the assert/deassert actually happened, there is no such mechanism currently
implemented.
In this specific case the GPIO purpose is to just to power on/off all codecs.
In my view with this approach it's enough to know that all codecs will be
powered on the first _deassert_ call and will be powered off on the last
_assert_ call.
/Viorel
next prev parent reply other threads:[~2020-11-19 16:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 22:20 [RFC PATCH] ASoC: ak4458: use reset control instead of reset gpio Viorel Suman (OSS)
2020-11-17 17:39 ` Mark Brown
2020-11-17 18:17 ` Viorel Suman
2020-11-18 11:55 ` Mark Brown
2020-11-19 16:22 ` Viorel Suman [this message]
2020-11-19 16:27 ` Mark Brown
2020-11-19 12:48 ` Peter Ujfalusi
2020-11-19 16:24 ` Viorel Suman
2020-11-20 13:40 ` Peter Ujfalusi
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