Re: [PATCH -next] drm/amd/dc: Remove a useless comparison

[Alex Deucher]

On Thu, May 7, 2020 at 9:35 AM ChenTao <chentao107@xxxxxxxxxx> wrote:
>
> Fix the following warning:
>
> 'en' is uint32_t and can never be negative.
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/gpio/hw_hpd.c:132:10: warning:
> comparison of unsigned expression < 0 is always false [-Wtype-limits]
>   if ((en < GPIO_DDC_LINE_MIN) || (en > GPIO_DDC_LINE_MAX)) {
> drivers/gpu/drm/amd/amdgpu/../display/dc/gpio/hw_generic.c:109:10: warning:
> comparison of unsigned expression < 0 is always false [-Wtype-limits]
>   if ((en < GPIO_DDC_LINE_MIN) || (en > GPIO_DDC_LINE_MAX)) {
>

While it's not required, I think it improves readability and protects
if the enum has negative values.  I think it would be better to change
the en var to signed.

Alex

> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: ChenTao <chentao107@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/amd/display/dc/gpio/hw_generic.c | 2 +-
>  drivers/gpu/drm/amd/display/dc/gpio/hw_hpd.c     | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/gpio/hw_generic.c b/drivers/gpu/drm/amd/display/dc/gpio/hw_generic.c
> index f9e847e6555d..6cd50232c432 100644
> --- a/drivers/gpu/drm/amd/display/dc/gpio/hw_generic.c
> +++ b/drivers/gpu/drm/amd/display/dc/gpio/hw_generic.c
> @@ -106,7 +106,7 @@ void dal_hw_generic_init(
>         enum gpio_id id,
>         uint32_t en)
>  {
> -       if ((en < GPIO_DDC_LINE_MIN) || (en > GPIO_DDC_LINE_MAX)) {
> +       if (en > GPIO_DDC_LINE_MAX) {
>                 ASSERT_CRITICAL(false);
>                 *hw_generic = NULL;
>         }
> diff --git a/drivers/gpu/drm/amd/display/dc/gpio/hw_hpd.c b/drivers/gpu/drm/amd/display/dc/gpio/hw_hpd.c
> index 692f29de7797..f91f426699c0 100644
> --- a/drivers/gpu/drm/amd/display/dc/gpio/hw_hpd.c
> +++ b/drivers/gpu/drm/amd/display/dc/gpio/hw_hpd.c
> @@ -129,7 +129,7 @@ void dal_hw_hpd_init(
>         enum gpio_id id,
>         uint32_t en)
>  {
> -       if ((en < GPIO_DDC_LINE_MIN) || (en > GPIO_DDC_LINE_MAX)) {
> +       if (en > GPIO_DDC_LINE_MAX) {
>                 ASSERT_CRITICAL(false);
>                 *hw_hpd = NULL;
>         }
> --
> 2.22.0
>
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