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Date: Fri, 16 Feb 2024 08:52:17 +0100
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Subject: Re: [PATCH v3 05/18] mux: add mux_chip_resume() function
To: Andy Shevchenko <andy@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
 Bartosz Golaszewski <brgl@bgdev.pl>, Tony Lindgren <tony@atomide.com>,
 Haojian Zhuang <haojian.zhuang@linaro.org>, Vignesh R <vigneshr@ti.com>,
 Aaro Koskinen <aaro.koskinen@iki.fi>,
 Janusz Krzysztofik <jmkrzyszt@gmail.com>, Andi Shyti
 <andi.shyti@kernel.org>, Peter Rosin <peda@axentia.se>,
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References: <20240102-j7200-pcie-s2r-v3-0-5c2e4a3fac1f@bootlin.com>
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 <Zc4t82V9czlEqamL@smile.fi.intel.com>
From: Thomas Richard <thomas.richard@bootlin.com>
In-Reply-To: <Zc4t82V9czlEqamL@smile.fi.intel.com>
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On 2/15/24 16:29, Andy Shevchenko wrote:
> On Thu, Feb 15, 2024 at 04:17:50PM +0100, Thomas Richard wrote:
>> The mux_chip_resume() function restores a mux_chip using the cached state
>> of each mux.
> 
> ...
> 
>> +int mux_chip_resume(struct mux_chip *mux_chip)
>> +{
>> +	int global_ret = 0;
>> +	int ret, i;
>> +
>> +	for (i = 0; i < mux_chip->controllers; ++i) {
>> +		struct mux_control *mux = &mux_chip->mux[i];
>> +
>> +		if (mux->cached_state == MUX_CACHE_UNKNOWN)
>> +			continue;
>> +
>> +		ret = mux_control_set(mux, mux->cached_state);
>> +		if (ret < 0) {
>> +			dev_err(&mux_chip->dev, "unable to restore state\n");
>> +			if (!global_ret)
>> +				global_ret = ret;
> 
> Hmm... This will record the first error and continue.

In the v2 we talked about this with Peter Rosin.

In fact, in the v1 (mux_chip_resume() didn't exists yet, everything was
done in the mmio driver) I had the same behavior: try to restore all
muxes and in case of error restore the first one.

I don't know what is the right solution. I just restored the behavior I
had in v1.

> 
>> +		}
>> +	}
>> +	return global_ret;
> 
> So here, we actually will get stale data in case there are > 1 failures.

Yes, indeed. But we will have an error message for each failure.

> 
>> +}
> 
-- 
Thomas Richard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com