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

[Ramon Fried]

On Thu, Dec 2, 2021 at 7:35 AM Marek Vasut <marex at denx.de> wrote:
>
> 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.
OK.