2023-05-23 13:09:29

by Tom Rix

Subject: [PATCH] drm/i915: simplify switch to if-elseif

clang with W=1 reports
drivers/gpu/drm/i915/display/intel_display.c:6012:3: error: unannotated
fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
case I915_FORMAT_MOD_X_TILED:
^

Only one case and the default does anything in this switch, so it should
be changed to an if-elseif.

Signed-off-by: Tom Rix <[email protected]>
---
drivers/gpu/drm/i915/display/intel_display.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 0490c6412ab5..1f852e49fc20 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5994,8 +5994,7 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
* Need to verify this for all gen9 platforms to enable
* this selectively if required.
*/
- switch (new_plane_state->hw.fb->modifier) {
- case DRM_FORMAT_MOD_LINEAR:
+ if (new_plane_state->hw.fb->modifier == DRM_FORMAT_MOD_LINEAR) {
/*
* FIXME: Async on Linear buffer is supported on ICL as
* but with additional alignment and fbc restrictions
@@ -6008,13 +6007,10 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
plane->base.base.id, plane->base.name);
return -EINVAL;
}
-
- case I915_FORMAT_MOD_X_TILED:
- case I915_FORMAT_MOD_Y_TILED:
- case I915_FORMAT_MOD_Yf_TILED:
- case I915_FORMAT_MOD_4_TILED:
- break;
- default:
+ } else if (!(new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_X_TILED ||
+ new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Y_TILED ||
+ new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Yf_TILED ||
+ new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_4_TILED)) {
drm_dbg_kms(&i915->drm,
"[PLANE:%d:%s] Modifier does not support async flips\n",
plane->base.base.id, plane->base.name);
--
2.27.0

2023-05-23 13:35:21

by Jani Nikula

Subject: Re: [PATCH] drm/i915: simplify switch to if-elseif

On Tue, 23 May 2023, Tom Rix <[email protected]> wrote:
> clang with W=1 reports
> drivers/gpu/drm/i915/display/intel_display.c:6012:3: error: unannotated
> fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
> case I915_FORMAT_MOD_X_TILED:
> ^
>
> Only one case and the default does anything in this switch, so it should
> be changed to an if-elseif.

Thanks for the patch.

If I wanted to fix this quickly, I'd just add the break in there.

If I wanted to fix this properly, I'd add a function
modifier_supports_async_flips() or something, and replace the switch
with:

if (!modifier_supports_async_flips(i915, new_plane_state->hw.fb->modifier)) {
drm_dbg_kms(&i915->drm, "[PLANE:%d:%s] Modifier does not support async flips\n",
plane->base.base.id, plane->base.name);
return -EINVAL;
}

But I wouldn't just replace the switch with if-elseif. It doesn't help
with the overall feeling that intel_async_flip_check_hw() is too long.

BR,
Jani.


>
> Signed-off-by: Tom Rix <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_display.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 0490c6412ab5..1f852e49fc20 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -5994,8 +5994,7 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
> * Need to verify this for all gen9 platforms to enable
> * this selectively if required.
> */
> - switch (new_plane_state->hw.fb->modifier) {
> - case DRM_FORMAT_MOD_LINEAR:
> + if (new_plane_state->hw.fb->modifier == DRM_FORMAT_MOD_LINEAR) {
> /*
> * FIXME: Async on Linear buffer is supported on ICL as
> * but with additional alignment and fbc restrictions
> @@ -6008,13 +6007,10 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
> plane->base.base.id, plane->base.name);
> return -EINVAL;
> }
> -
> - case I915_FORMAT_MOD_X_TILED:
> - case I915_FORMAT_MOD_Y_TILED:
> - case I915_FORMAT_MOD_Yf_TILED:
> - case I915_FORMAT_MOD_4_TILED:
> - break;
> - default:
> + } else if (!(new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_X_TILED ||
> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Y_TILED ||
> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Yf_TILED ||
> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_4_TILED)) {
> drm_dbg_kms(&i915->drm,
> "[PLANE:%d:%s] Modifier does not support async flips\n",
> plane->base.base.id, plane->base.name);

--
Jani Nikula, Intel Open Source Graphics Center

2023-05-26 10:05:32

by Jani Nikula

Subject: Re: [Intel-gfx] [PATCH] drm/i915: simplify switch to if-elseif

On Tue, 23 May 2023, Jani Nikula <[email protected]> wrote:
> On Tue, 23 May 2023, Tom Rix <[email protected]> wrote:
>> clang with W=1 reports
>> drivers/gpu/drm/i915/display/intel_display.c:6012:3: error: unannotated
>> fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
>> case I915_FORMAT_MOD_X_TILED:
>> ^
>>
>> Only one case and the default does anything in this switch, so it should
>> be changed to an if-elseif.
>
> Thanks for the patch.
>
> If I wanted to fix this quickly, I'd just add the break in there.

I've just applied [1] doing this.

I'm still open to the cleanup suggested below, if you're up for it.


BR,
Jani.


[1] https://patchwork.freedesktop.org/patch/msgid/20230524-intel_async_flip_check_hw-implicit-fallthrough-v1-1-83de89e376a1@kernel.org

>
> If I wanted to fix this properly, I'd add a function
> modifier_supports_async_flips() or something, and replace the switch
> with:
>
> if (!modifier_supports_async_flips(i915, new_plane_state->hw.fb->modifier)) {
> drm_dbg_kms(&i915->drm, "[PLANE:%d:%s] Modifier does not support async flips\n",
> plane->base.base.id, plane->base.name);
> return -EINVAL;
> }
>
> But I wouldn't just replace the switch with if-elseif. It doesn't help
> with the overall feeling that intel_async_flip_check_hw() is too long.
>
> BR,
> Jani.
>
>
>>
>> Signed-off-by: Tom Rix <[email protected]>
>> ---
>> drivers/gpu/drm/i915/display/intel_display.c | 14 +++++---------
>> 1 file changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>> index 0490c6412ab5..1f852e49fc20 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -5994,8 +5994,7 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
>> * Need to verify this for all gen9 platforms to enable
>> * this selectively if required.
>> */
>> - switch (new_plane_state->hw.fb->modifier) {
>> - case DRM_FORMAT_MOD_LINEAR:
>> + if (new_plane_state->hw.fb->modifier == DRM_FORMAT_MOD_LINEAR) {
>> /*
>> * FIXME: Async on Linear buffer is supported on ICL as
>> * but with additional alignment and fbc restrictions
>> @@ -6008,13 +6007,10 @@ static int intel_async_flip_check_hw(struct intel_atomic_state *state, struct in
>> plane->base.base.id, plane->base.name);
>> return -EINVAL;
>> }
>> -
>> - case I915_FORMAT_MOD_X_TILED:
>> - case I915_FORMAT_MOD_Y_TILED:
>> - case I915_FORMAT_MOD_Yf_TILED:
>> - case I915_FORMAT_MOD_4_TILED:
>> - break;
>> - default:
>> + } else if (!(new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_X_TILED ||
>> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Y_TILED ||
>> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_Yf_TILED ||
>> + new_plane_state->hw.fb->modifier == I915_FORMAT_MOD_4_TILED)) {
>> drm_dbg_kms(&i915->drm,
>> "[PLANE:%d:%s] Modifier does not support async flips\n",
>> plane->base.base.id, plane->base.name);

--
Jani Nikula, Intel Open Source Graphics Center