(dropping Tixy as I am sure it will bounce, he left/retired from Linaro
long back)
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.
Agreed.
> 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.
>
Thanks a lot for finding and fixing the bug!
> Fix this by getting rid of the ternary.
>
> 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;
This could be still an issue, ideally I would prefer to pass the return
value via argument pointer and always return success/failure as return
value. Can't remember any reason for this. Since this is old interface
with limited platform to test, I think returning 0 as clock rate on error
should be fine as Cristain suggested. If you agree with that, I can
fix up when applying.
If you don't, we can look at changing the scpi interface to clock driver
which will anyway need to do the same(i.e. send 0 in case of error)
Let me know.
--
Regards,
Sudeep
