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SubjectRe: [PATCH] pci: dwc: add a check for resetting gpio
Hi Kangjie,

Thanks for the patch.

On Tue, Dec 25, 2018 at 08:22:36PM -0600, Kangjie Lu wrote:
> devm_gpio_request_one() could fail. The fix checks its status and issues
> an error if it fails.
>
> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
> ---
> drivers/pci/controller/dwc/pci-exynos.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-exynos.c b/drivers/pci/controller/dwc/pci-exynos.c
> index cee5f2f590e2..e3a045e215d2 100644
> --- a/drivers/pci/controller/dwc/pci-exynos.c
> +++ b/drivers/pci/controller/dwc/pci-exynos.c
> @@ -226,9 +226,12 @@ static void exynos_pcie_assert_reset(struct exynos_pcie *ep)
> struct dw_pcie *pci = ep->pci;
> struct device *dev = pci->dev;
>
> - if (ep->reset_gpio >= 0)
> - devm_gpio_request_one(dev, ep->reset_gpio,
> - GPIOF_OUT_INIT_HIGH, "RESET");
> + if (ep->reset_gpio >= 0) {
> + if (devm_gpio_request_one(dev, ep->reset_gpio,
> + GPIOF_OUT_INIT_HIGH, "RESET"))
> + dev_err(dev, "Failed requesting reset gpio %d\n",
> + ep->reset_gpio);
> + }

Even before your patch, this code doesn't make sense to me.

devm_gpio_request_one() is a setup function and should be called in
the probe path. The "assert_reset" path should do something like
gpio_set_value(). See other callers, e.g.,

imx6_pcie_probe()
histb_pcie_probe()
mvebu_pcie_parse_port()

I'm skeptical that exynos_pcie_assert_reset() ever worked as intended,
so let's straighten that out before worrying about checking the return
code from devm_gpio_request_one().

The result should be two patches: (1) fix the devm_gpio_request_one()
usage, and (2) check the devm_gpio_request_one() return value.

> }

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