2020-05-07 11:29:26

by Chen Tao

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

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)) {

Reported-by: Hulk Robot <[email protected]>
Signed-off-by: ChenTao <[email protected]>
---
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

2020-05-07 19:44:28

by Alex Deucher

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

On Thu, May 7, 2020 at 9:35 AM ChenTao <[email protected]> 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 <[email protected]>
> Signed-off-by: ChenTao <[email protected]>
> ---
> 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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