From: Mark Brown <broonie@kernel.org>
To: Peter Rosin <peda@axentia.se>
Cc: "Péter Ujfalusi" <peter.ujfalusi@gmail.com>,
"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Takashi Iwai" <tiwai@suse.com>,
"Liam Girdwood" <lgirdwood@gmail.com>,
"Kirill Marinushkin" <kmarinushkin@birdec.com>
Subject: Re: [PATCH] ASoC: pcm512x: Mend accesses to the I2S_1 and I2S_2 registers
Date: Tue, 21 Sep 2021 12:11:28 +0100 [thread overview]
Message-ID: <20210921111128.GA4203@sirena.org.uk> (raw)
In-Reply-To: <8ee31fd2-3fbe-f5da-a030-c6b677c7f398@axentia.se>
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On Tue, Sep 21, 2021 at 08:37:28AM +0200, Peter Rosin wrote:
> I expected it to just work to mark the register as readable and do
> without the default value (i.e. the way it was before my patch). What
> I don't understand is why regmap returns -EBUSY in that case. That
> doesn't make sense to me. Perhaps that -EBUSY is propagated from the
> I2C layer, but in that case, why is it then ok to do a write to
> another register at the same spot in the code? So, why -EBUSY?
Actually one thing that can trigger this now I think about it is
attempting to access a volatile register when the device is in cache
only mode for power management reasons - if the device is in cache only
mode then you can't do a hardware read so volatile registers become
inaccessible.
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next prev parent reply other threads:[~2021-09-21 11:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 14:49 Peter Rosin
[not found] ` <ae4b25f1-2b2c-d937-e23d-0f7d23bdf0c4@gmail.com>
2021-09-20 19:37 ` Peter Rosin
2021-09-20 21:29 ` Mark Brown
2021-09-21 6:37 ` Peter Rosin
2021-09-21 11:11 ` Mark Brown [this message]
2021-09-21 4:20 ` Péter Ujfalusi
2021-09-21 6:52 ` Peter Rosin
2021-09-21 8:10 ` Peter Rosin
2021-09-21 8:48 ` Peter Rosin
2021-09-21 12:01 ` Mark Brown
2021-09-21 13:30 ` Peter Rosin
2021-09-21 15:25 ` Mark Brown
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