[PATCH] net: eth-phy: Handle gpio_request_by_name() return value

[Marek Vasut]

On 12/2/21 06:03, Ramon Fried wrote:
> On Tue, Nov 16, 2021 at 7:52 AM Ramon Fried <rfried.dev at gmail.com> wrote:
>>
>> On Sat, Nov 13, 2021 at 4:23 AM Marek Vasut <marex at denx.de> wrote:
>>>
>>> The gpio_request_by_name() returns zero in case of success, however the
>>> conditional return value check in gpio_request_by_name() checks only for
>>> (ret != -ENOENT) and if the condition is true, returns ret outright.
>>>
>>> This leads to a situation where successful gpio_request_by_name() return
>>> leads to immediate successful eth_phy_of_to_plat() return as well, and
>>> to skipped parsing of "reset-assert-us" and "reset-deassert-us", so the
>>> PHY driver operates with valid reset GPIO, but with assert/deassert times
>>> set to default, which is 0, instead of the values from DT. This breaks
>>> PHY reset.
>>>
>>> Fix this by checking if return value is non-zero and then for this one
>>> single allowed non-zero return value, -ENOENT.
>>>
>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>> Cc: Ramon Fried <rfried.dev at gmail.com>
>>> ---
>>>   drivers/net/eth-phy-uclass.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/eth-phy-uclass.c b/drivers/net/eth-phy-uclass.c
>>> index c04bab944d6..a9b358ee234 100644
>>> --- a/drivers/net/eth-phy-uclass.c
>>> +++ b/drivers/net/eth-phy-uclass.c
>>> @@ -138,7 +138,7 @@ static int eth_phy_of_to_plat(struct udevice *dev)
>>>          ret = gpio_request_by_name(dev, "reset-gpios", 0,
>>>                                     &uc_priv->reset_gpio,
>>>                                     GPIOD_IS_OUT);
>>> -       if (ret != -ENOENT)
>>> +       if (ret && ret != -ENOENT)
>>>                  return ret;
>>>
>>>          uc_priv->reset_assert_delay = dev_read_u32_default(dev, "reset-assert-us", 0);
>>> --
>>> 2.33.0
>>>
>> Reviewed-by: Ramon Fried <rfried.dev at gmail.com>
> Applied to u-boot-net/next,

Note that this fixes a grave bug in the PHY reset code, so it should go 
into current release.