Re: [PATCH v2 04/15] mux: add mux_chip_resume() function

Thomas Richard
2024-01-30T16:25:05Z

On 1/30/24 09:25, Peter Rosin wrote:
> Hi!
>
> 2024-01-26 at 15:36, Thomas Richard wrote:
>> The mux_chip_resume() function restores a mux_chip using the cached state
>> of each mux.
>>
>> Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
>> ---
>> drivers/mux/core.c | 27 +++++++++++++++++++++++++++
>> include/linux/mux/driver.h | 1 +
>> 2 files changed, 28 insertions(+)
>>
>> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
>> index 775816112932..896f74b34eb8 100644
>> --- a/drivers/mux/core.c
>> +++ b/drivers/mux/core.c
>> @@ -215,6 +215,33 @@ void mux_chip_free(struct mux_chip *mux_chip)
>> }
>> EXPORT_SYMBOL_GPL(mux_chip_free);
>>
>> +/**
>> + * mux_chip_resume() - restores the mux-chip state
>> + * @mux_chip: The mux-chip to resume.
>> + *
>> + * Restores the mux-chip state.
>> + *
>> + * Return: Zero on success or a negative errno on error.
>> + */
>> +int mux_chip_resume(struct mux_chip *mux_chip)
>> +{
>> + 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) {
>> + ret = mux_control_set(mux, mux->cached_state);
>> + if (ret < 0) {
>> + dev_err(&mux_chip->dev, "unable to restore state\n");
>> + return ret;
>
> I'm don't know what is expected of the core resume code on error,
> but is it ok to return on first failure? Is it not better to try
> to restore all muxes and return zero if all is well or the first
> failure when something is up?
>
> But maybe the resume is completely dead anyway if there is any
> failure? In that case the above early return is fine, I guess...
>

In the first iteration of this series (when it was done in mmio driver),
it restored all muxes and returned zero or the first failure.
I don't know why I changed the behaviour.
For me it's better to try to restores all muxes.

--
Thomas Richard, Bootlin
Embedded Linux and Kernel engineering