Re: [PATCH net v1 1/1] net: dsa: realtek: use gpiod_set_value_cansleep for reset GPIO

> From: Ahmad Fatoum <[email protected]>
>
> rtl83xx_reset_assert() and rtl83xx_reset_deassert() are only called from
> the probe path, which may sleep and is not timing-critical.  When the
> reset GPIO is provided by a sleeping controller such as an I2C I/O
> expander, gpiod_set_value() warns:
>
>   WARNING: drivers/gpio/gpiolib.c:4030 at gpiod_set_value+0x44/0x80, CPU#1: kworker/u16:4/61
>   Hardware name: B&O MAP CA33 Rev f (UNKNOWN) (DT)
>   Workqueue: events_unbound deferred_probe_work_func
>   pc : gpiod_set_value+0x44/0x80
>   lr : rtl83xx_probe+0x1d8/0x3a0
>   Call trace:
>    gpiod_set_value+0x44/0x80 (P)
>    rtl83xx_probe+0x1d8/0x3a0
>    realtek_mdio_probe+0x24/0xa0
>    mdio_probe+0x38/0x78
>    really_probe+0xc4/0x3e0
>    __driver_probe_device+0x15c/0x1b8
>    driver_probe_device+0xb4/0x120
>    __device_attach_driver+0xb8/0x1a0
>    bus_for_each_drv+0x88/0xf0
>    __device_attach+0xa0/0x1d8
>    device_initial_probe+0x54/0x68
>    bus_probe_device+0x38/0xa0
>    deferred_probe_work_func+0xb8/0x120
>    process_one_work+0x184/0x4e8
>    worker_thread+0x188/0x308
>    kthread+0x130/0x150
>    ret_from_fork+0x10/0x20
>
> Switch both helpers to gpiod_set_value_cansleep() so such a reset GPIO can
> be used without triggering the warning.
>
> The reset GPIO has been driven with the non-sleeping gpiod_set_value()
> since the driver was added in v4.19.  The call has since been refactored
> across several files - from realtek-smi.c / realtek-mdio.c into the common
> rtl83xx.c module and then into the rtl83xx_reset_assert() and
> rtl83xx_reset_deassert() helpers (both in v6.9).  This patch therefore
> applies as-is only to kernels that carry those helpers (v6.9+); older
> stable kernels need the same gpiod_set_value_cansleep() conversion at the
> corresponding open-coded call sites.
>
> Fixes: d8652956cf37 ("net: dsa: realtek-smi: Add Realtek SMI driver")
> Cc: <[email protected]> # 6.9.x
> Signed-off-by: Ahmad Fatoum <[email protected]>
> Co-developed-by: Oleksij Rempel <[email protected]>
> Signed-off-by: Oleksij Rempel <[email protected]>
> ---
>  drivers/net/dsa/realtek/rtl83xx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/dsa/realtek/rtl83xx.c b/drivers/net/dsa/realtek/rtl83xx.c
> index 09fd64880232..8121ec12fd8b 100644
> --- a/drivers/net/dsa/realtek/rtl83xx.c
> +++ b/drivers/net/dsa/realtek/rtl83xx.c
> @@ -334,7 +334,7 @@ void rtl83xx_reset_assert(struct realtek_priv *priv)
>                          "Failed to assert the switch reset control: %pe\n",
>                          ERR_PTR(ret));
>
> -       gpiod_set_value(priv->reset, true);
> +       gpiod_set_value_cansleep(priv->reset, true);
>  }
>
>  void rtl83xx_reset_deassert(struct realtek_priv *priv)
> @@ -347,7 +347,7 @@ void rtl83xx_reset_deassert(struct realtek_priv *priv)
>                          "Failed to deassert the switch reset control: %pe\n",
>                          ERR_PTR(ret));
>
> -       gpiod_set_value(priv->reset, false);
> +       gpiod_set_value_cansleep(priv->reset, false);
>  }
>
>  /**
> --
> 2.47.3
>

Reviewed-by: Luiz Angelo Daros de Luca <[email protected]>

Regards,

Luiz