linux-kernel - Re: [PATCH] regmap: sdw: check for invalid multi-register writes config

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Message-ID: <f9484905-fc8d-450a-bc52-00ba99db0d1f@sirena.org.uk>
Date:   Tue, 23 May 2023 18:25:17 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     gregkh@...uxfoundation.org, rafael@...nel.org,
        ckeepax@...nsource.cirrus.com, tanureal@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH] regmap: sdw: check for invalid multi-register writes
 config

On Tue, May 23, 2023 at 06:13:25PM +0100, Srinivas Kandagatla wrote:
> On 23/05/2023 17:58, Mark Brown wrote:
> > On Tue, May 23, 2023 at 04:47:47PM +0100, Srinivas Kandagatla wrote:

> > > +	/* Only bulk writes are supported not multi-register writes */
> > > +	if (config->can_multi_write)
> > > +		return -ENOTSUPP;

> > This doesn't seem like the right fix - I'd expect us to simply choose
> > not to use multiple writes, with an additional flag/check for bus
> > support.

> Is there a way to check if bus support multi-register writes?

> All I can see from the code is that regmap can_multi_write is set based on
> regmap_config from device and write callback from bus.

No, that'd be the additional flag/check bit - see also my question about
if this is something the hardware actually has or not on the CODEC patch.

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