linux-kernel - Re: [PATCH 02/18] spi: stm32-spi: defer probe for reset

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Message-ID: <20200807140154.GK5435@sirena.org.uk>
Date:   Fri, 7 Aug 2020 15:01:54 +0100
From:   Mark Brown <broonie@...nel.org>
To:     amelie.delaunay@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, linux-spi@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        fabrice.gasnier@...com
Subject: Re: [PATCH 02/18] spi: stm32-spi: defer probe for reset

On Fri, Aug 07, 2020 at 03:42:54PM +0200, Alain Volmat wrote:
> On Wed, Aug 05, 2020 at 11:49:06AM +0100, Mark Brown wrote:
> > On Wed, Aug 05, 2020 at 09:01:57AM +0200, Alain Volmat wrote:

> > > -	rst = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> > > -	if (!IS_ERR(rst)) {
> > > +	rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> > > +	if (rst) {
> > > +		if (IS_ERR(rst)) {
> > > +			ret = PTR_ERR(rst);
> > > +			if (ret != -EPROBE_DEFER)
> > > +				dev_err(&pdev->dev, "reset get failed: %d\n",
> > > +					ret);
> > > +			goto err_clk_disable;
> > > +		}

> > This will not provide any diagnostics when deferring which isn't very
> > helpful if there's issues.

> Do you mean that a message when deferring would be needed ?

Yes, if for examaple the reset driver isn't being built then the driver
will defer for ever waiting for it to instantiate and the user will have
to have some method for figuring out what it's waiting for.

> I am worrying that this would lead to having too much noise during boot
> since probe deferring is kinda common. Of course it can also be due to a bad
> configuration of the kernel as well but having looked around I think that
> usually driver are rather silent in case of deferring.

This is not something that should be open coded in your driver.

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