Hi,
On Thu, Apr 22, 2021 at 12:02:29PM +0300, Dan Carpenter wrote:
> How type promotion works in ternary expressions is a bit tricky.
> The problem is that scpi_clk_get_val() returns longs, "ret" is a int
> which holds a negative error code, and le32_to_cpu() is an unsigned int.
> We want the negative error code to be cast to a negative long. But
> because le32_to_cpu() is an u32 then "ret" is type promoted to u32 and
> becomes a high positive and then it is promoted to long and it is still
> a high positive value.
>
> Fix this by getting rid of the ternary.
I wonder how/if the callers up in the stack check/expect ever effectively for a
2-complement negative value inside the returned unsigned long...given that this
plugs finally into CLK framework struct clk_ops.recalc_rate via clk-scpi.c which
also expects unsigned long....but that's another story.
FWIW regarding this patch:
Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Thanks
Cristian
>
> Fixes: 8cb7cf56c9fe ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> drivers/firmware/arm_scpi.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
> index d0dee37ad522..3bf61854121d 100644
> --- a/drivers/firmware/arm_scpi.c
> +++ b/drivers/firmware/arm_scpi.c
> @@ -552,8 +552,10 @@ static unsigned long scpi_clk_get_val(u16 clk_id)
>
> ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,
> sizeof(le_clk_id), &rate, sizeof(rate));
> + if (ret)
> + return ret;
>
> - return ret ? ret : le32_to_cpu(rate);
> + return le32_to_cpu(rate);
> }
>
> static int scpi_clk_set_val(u16 clk_id, unsigned long rate)
> --
> 2.30.2
>
