Re: [PATCH v2 1/3] serial: mtk: use ulong for clk_rate

Le ven. 31 juil. 2026 à 21:39, David Lechner <[email protected]> a écrit :
>
> From: Suhrid Subramaniam <[email protected]>
>
> Use ulong for return value of clk_get_rate() in the MediaTek serial
> driver.
>
> IS_ERR_VALUE() does a signed 64-bit comparison against the range of
> possible error codes. If clk_get_rate() returns an error, assigning this
> to a u32 truncates the top 32 bits making the value smaller, defeating
> IS_ERR_VALUE() and producing a garbage divisor that hangs the UART.
>
> Fixes: 3b17f2e2c2a9 ("serial: mtk: add support for using dynamic baud clock souce")
> Signed-off-by: Suhrid Subramaniam <[email protected]>
> Signed-off-by: David Lechner <[email protected]>
> ---
>  drivers/serial/serial_mtk.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/serial/serial_mtk.c b/drivers/serial/serial_mtk.c
> index 01cc415efdd..28e87f485a2 100644
> --- a/drivers/serial/serial_mtk.c
> +++ b/drivers/serial/serial_mtk.c
> @@ -213,7 +213,7 @@ static int _mtk_serial_pending(struct mtk_serial_priv *priv, bool input)
>  static int mtk_serial_setbrg(struct udevice *dev, int baudrate)
>  {
>         struct mtk_serial_priv *priv = dev_get_priv(dev);
> -       u32 clk_rate;
> +       ulong clk_rate;
>
>         clk_rate = clk_get_rate(&priv->clk);
>         if (IS_ERR_VALUE(clk_rate) || clk_rate == 0)
> @@ -266,6 +266,7 @@ static int mtk_serial_of_to_plat(struct udevice *dev)
>  {
>         struct mtk_serial_priv *priv = dev_get_priv(dev);
>         fdt_addr_t addr;
> +       ulong clk_rate;
>         int err;
>
>         addr = dev_read_addr(dev);
> @@ -282,8 +283,8 @@ static int mtk_serial_of_to_plat(struct udevice *dev)
>                         return -EINVAL;
>                 }
>         } else {
> -               err = clk_get_rate(&priv->clk);
> -               if (IS_ERR_VALUE(err)) {
> +               clk_rate = clk_get_rate(&priv->clk);
> +               if (IS_ERR_VALUE(clk_rate)) {
>                         dev_err(dev, "invalid baud clock\n");
>                         return -EINVAL;
>                 }
>
> --
> 2.43.0
>
Reviewed-by: Julien Stephan <[email protected]>