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SubjectRe: [PATCH] PCI: tegra: Fix support for GPIO based PERST#
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On 05-Jul-19 3:20 PM, Lorenzo Pieralisi wrote:
> On Fri, Jul 05, 2019 at 09:48:50AM +0100, Jon Hunter wrote:
>> Commit 5e5e9c23f82a ("PCI: tegra: Add support for GPIO based PERST#")
>> calls the function devm_gpiod_get_from_of_node() to request a GPIO.
>> Unfortunately, around the same time this was merged, commit 025bf37725f1
>> ("gpio: Fix return value mismatch of function gpiod_get_from_of_node()")
>> was also merged to fix the return value of the function
>> devm_gpiod_get_from_of_node() that was incorrectly returning NULL
>> instead of an error pointer encoded with -ENOENT if no GPIO was found.
>> When this fix for the GPIO subsystem was merged, PCI support for Tegra
>> devices that did not provide a GPIO for the PERST# (which is optional)
>> broke because the Tegra PCI driver was expecting NULL to be returned if
>> no GPIO was present and not -ENOENT.
>>
>> Fix this by checking to see if -ENOENT is returned from the function
>> devm_gpiod_get_from_of_node(), to indicate there is no GPIO for PERST#
>> present, and if this is the case set the variable 'reset_gpio' to NULL.
>> If the variable 'reset_gpio' is NULL then the Tegra PCI driver will
>> fallback to using the AFI register to toggle the PERST#. Finally,
>> correct the comment now that NULL is no longer returned from
>> devm_gpiod_get_from_of_node().
>>
>> Fixes: 5e5e9c23f82a ("PCI: tegra: Add support for GPIO based PERST#")
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> drivers/pci/controller/pci-tegra.c | 16 ++++++++++------
>> 1 file changed, 10 insertions(+), 6 deletions(-)
> Can I squash this in the original commit (ie Fixes: tag above) ? I do
> not think there is any issue with that, if there is please do let me
> know.
>
> Thanks,
> Lorenzo

Reviewed-by: Manikanta Maddireddy

Thank you Jon for publishing the fix.

Hi Lorenzo,

Yes, this patch can be squashed in the original commit.

Apologies for the inconvenience.

Manikanta

>> diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
>> index 9cc03a2549c0..ff8a346f3e04 100644
>> --- a/drivers/pci/controller/pci-tegra.c
>> +++ b/drivers/pci/controller/pci-tegra.c
>> @@ -2295,18 +2295,22 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
>> }
>>
>> /*
>> - * Returns null if reset-gpios property is not populated and
>> - * fall back to using AFI per port register to toggle PERST#
>> - * SFIO line.
>> + * Returns -ENOENT if reset-gpios property is not populated
>> + * and in this case fall back to using AFI per port register
>> + * to toggle PERST# SFIO line.
>> */
>> rp->reset_gpio = devm_gpiod_get_from_of_node(dev, port,
>> "reset-gpios", 0,
>> GPIOD_OUT_LOW,
>> label);
>> if (IS_ERR(rp->reset_gpio)) {
>> - err = PTR_ERR(rp->reset_gpio);
>> - dev_err(dev, "failed to get reset GPIO: %d\n", err);
>> - return err;
>> + if (PTR_ERR(rp->reset_gpio) == -ENOENT) {
>> + rp->reset_gpio = NULL;
>> + } else {
>> + dev_err(dev, "failed to get reset GPIO: %d\n",
>> + err);
>> + return PTR_ERR(rp->reset_gpio);
>> + }
>> }
>>
>> list_add_tail(&rp->list, &pcie->ports);
>> --
>> 2.17.1
>>

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