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From:   Dmitry Osipenko <digetx@gmail.com>
To:     Marcel Ziswiler <marcel.ziswiler@toradex.com>,
        "broonie@kernel.org" <broonie@kernel.org>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "jonathanh@nvidia.com" <jonathanh@nvidia.com>,
        "thierry.reding@gmail.com" <thierry.reding@gmail.com>,
        "tiwai@suse.com" <tiwai@suse.com>,
        "lgirdwood@gmail.com" <lgirdwood@gmail.com>,
        "perex@perex.cz" <perex@perex.cz>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
        "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>
Subject: Re: [PATCH 2/2] ASoC: tegra: probe deferral error reporting
Date:   Sat, 21 Jul 2018 15:15:37 +0300
Message-ID: <102145026.ENfUlVqMES@dimapc>
In-Reply-To: <2195096.d8yV6ZqeS2@dimapc>
References: <20180720080424.31505-1-marcel@ziswiler.com> <1532174119.19673.24.camel@toradex.com> <2195096.d8yV6ZqeS2@dimapc>
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On Saturday, 21 July 2018 15:03:57 MSK Dmitry Osipenko wrote:
> On Saturday, 21 July 2018 14:55:21 MSK Marcel Ziswiler wrote:
> > On Sat, 2018-07-21 at 14:17 +0300, Dmitry Osipenko wrote:
> > > On Saturday, 21 July 2018 12:56:15 MSK Mark Brown wrote:
> > > > On Fri, Jul 20, 2018 at 12:31:07PM +0000, Marcel Ziswiler wrote:
> > > > > On Fri, 2018-07-20 at 13:16 +0100, Mark Brown wrote:
> > > > > > >  	ac97->sync_gpio = of_get_named_gpio(pdev-
> > > > > > > >
> > > > > > > >dev.of_node,
> > > > > > > >
> > > > > > >  					    "nvidia,codec-
> > > > > > > 
> > > > > > > sync-
> > > > > > > 
> > > > > > > gpio", 0);
> > > > > > > 
> > > > > > >  	if (!gpio_is_valid(ac97->sync_gpio)) {
> > > > > > > 
> > > > > > > -		dev_err(&pdev->dev, "no codec-sync GPIO
> > > > > > > supplied\n");
> > > > > > > +		ret = ac97->sync_gpio;
> > > > > > > +		dev_err(&pdev->dev, "no codec-sync GPIO
> > > > > > > supplied:
> > > > > > > %d\n", ret);
> > > > > > > 
> > > > > > >  		goto err_clk_put;
> > > > > > >  	
> > > > > > >  	}
> > > > > > 
> > > > > > This isn't reporting an error code associated with the attempt
> > > > > > to
> > > > > > find a
> > > > > > codec-sync GPIO, it's the result of some other operation.
> > > > > 
> > > > > What exactly is then the of_get_named_gpio() above please doing
> > > > > if
> > > > > not getting the codec sync GPIO? I am not following you, sorry.
> > > > 
> > > > It's not in any way involved in setting the value of ret, whatever
> > > > value
> > > > that has it's nothing to do with that operation.
> > > 
> > > The comment to gpio_is_valid() says that it "Returns GPIO number to
> > > use with
> > > Linux generic GPIO API, or one of the errno value on the error
> > > condition".
> > > Comment doesn't explicitly states that the returned GPIO number is
> > > always
> > > valid, but it is kinda implied.
> > 
> > Do you mean I should be assigning the return value of gpio_is_valid()
> > to ret and use that instead?
> 
> No, gpio_is_valid() returns a boolean. I think your patch is fine as it is
> is.
> 
> Probably Mark meant something like this:
> 
>         ac97->sync_gpio = of_get_named_gpio(pdev->dev.of_node,
>                                             "nvidia,codec-sync-gpio", 0);
>         if (ac97->sync_gpio < 0) {
>                 ret = ac97->sync_gpio;
>                 dev_err(&pdev->dev, "no codec-sync GPIO supplied: %d\n",
> ret); goto err_clk_put;
>         }
> 
>         if (!gpio_is_valid(ac97->sync_gpio)) {
>                 ret = -EINVAL;
>                 goto err_clk_put;
>        }
> 
> But that is not needed because of_get_named_gpio() returns either a valid
> GPIO number or a error code.

Also note that tegra20_ac97 code doesn't check the returned value of:

	gpio_request(workdata->sync_gpio, "codec-sync");

That is a bit fragile. Probably would be better to move the GPIO requesting to 
the drivers probe function using the devm_gpio_request_one() and fail the 
driver probing if requesting fails. That should be a distinct patch if you'll 
want to implement that.