linux-kernel - Re: [PATCH v2 3/4] PCI: imx6: Convert to agnostic GPIO API

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Date: Tue, 23 Apr 2024 16:16:36 -0400
From: Frank Li <Frank.li@....com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	linux-omap@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev, linux-amlogic@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org, linux-tegra@...r.kernel.org,
	Vignesh Raghavendra <vigneshr@...com>,
	Siddharth Vadapalli <s-vadapalli@...com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Richard Zhu <hongxing.zhu@....com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, Yue Wang <yue.wang@...ogic.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Kevin Hilman <khilman@...libre.com>,
	Jerome Brunet <jbrunet@...libre.com>,
	Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
	Xiaowei Song <songxiaowei@...ilicon.com>,
	Binghui Wang <wangbinghui@...ilicon.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Pali Rohár <pali@...nel.org>
Subject: Re: [PATCH v2 3/4] PCI: imx6: Convert to agnostic GPIO API

On Tue, Apr 23, 2024 at 11:03:59PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 23, 2024 at 03:56:56PM -0400, Frank Li wrote:
> > On Tue, Apr 23, 2024 at 08:19:06PM +0300, Andy Shevchenko wrote:
> 
> ...
> 
> > > +	imx6_pcie->reset_gpiod =
> > > +		devm_gpiod_get_optional(dev, "reset",
> > > +			imx6_pcie->gpio_active_high ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW);
> > > +	if (IS_ERR(imx6_pcie->reset_gpiod))
> > > +		return dev_err_probe(dev, PTR_ERR(imx6_pcie->reset_gpiod),
> > > +				     "unable to get reset gpio\n");
> > 
> > Small problem here. err message "unable to get reset gpio\n" will print
> > when -EPROBE_DEFER happen. EPROBE_DEFER is quite common when use i2c
> > expand gpio chip.
> 
> I'm not sure how you come to this conclusion. Can you elaborate, please?
> P.S> I do not see a problem as described.

If i2c gpio-expander driver have not load when imx6_pcie probe, I supposed
devm_gpiod_get_optional() will return -EPROBE_DEFER, 

if (IS_ERR(imx6_pcie->reset_gpiod)) should be true. then dev_err_probe()
will run and print "unable to get reset gpio\n" with error code
-EPROBE_DEFER.

driver framework will retry imx6_pcie probe again when a new device appear.
it may retry sevial times utill i2c gpio-expander driver probe success or
timeout.

Frank

> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>