Nouveau - Jul 2022 - [PATCH] drm/nouveau/bios: set info only when the return is not 0

clang static analysis reports
drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c:68:17: warning: The right operand
of '*' is a garbage value [core.UndefinedBinaryOperatorResult]
        switch (!!data * *ver) {
                       ^ ~~~~
A switch statement with only a default should be reduced to an if.

If nvbios_pmuEp() returns 0, via the data variable, the output info parameter
is not used.  So set info only when data is not 0.

The struct nvbios_pmuE only has the type and data elements.  Since both of these
are explicitly set, memset is not needed.  So remove it.

Signed-off-by: Tom Rix <trix at redhat.com>
---
 drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
index b4a308f3cf7b..49e2664a734c 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
@@ -64,12 +64,9 @@ nvbios_pmuEp(struct nvkm_bios *bios, int idx, u8 *ver, u8
*hdr,
 	     struct nvbios_pmuE *info)
 {
 	u32 data = nvbios_pmuEe(bios, idx, ver, hdr);
-	memset(info, 0x00, sizeof(*info));
-	switch (!!data * *ver) {
-	default:
+	if (data) {
 		info->type = nvbios_rd08(bios, data + 0x00);
 		info->data = nvbios_rd32(bios, data + 0x02);
-		break;
 	}
 	return data;
 }
-- 
2.27.0

Reviewed-by: Lyude Paul <lyude at redhat.com>

Currently on flakey internet in the back of a car, so I probably won't be
able
to push this until I get back tonight or early tomorrow

On Sat, 2022-07-02 at 11:39 -0400, Tom Rix wrote:
> clang static analysis reports
> drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c:68:17: warning: The right
> operand of '*' is a garbage value
[core.UndefinedBinaryOperatorResult]
> ??????? switch (!!data * *ver) {
> ?????????????????????? ^ ~~~~
> A switch statement with only a default should be reduced to an if.
> 
> If nvbios_pmuEp() returns 0, via the data variable, the output info
> parameter
> is not used.? So set info only when data is not 0.
> 
> The struct nvbios_pmuE only has the type and data elements.? Since both of
> these
> are explicitly set, memset is not needed.? So remove it.
> 
> Signed-off-by: Tom Rix <trix at redhat.com>
> ---
> ?drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c | 5 +----
> ?1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> index b4a308f3cf7b..49e2664a734c 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/pmu.c
> @@ -64,12 +64,9 @@ nvbios_pmuEp(struct nvkm_bios *bios, int idx, u8 *ver,
u8
> *hdr,
> ???????????? struct nvbios_pmuE *info)
> ?{
> ????????u32 data = nvbios_pmuEe(bios, idx, ver, hdr);
> -???????memset(info, 0x00, sizeof(*info));
> -???????switch (!!data * *ver) {
> -???????default:
> +???????if (data) {
> ????????????????info->type = nvbios_rd08(bios, data + 0x00);
> ????????????????info->data = nvbios_rd32(bios, data + 0x02);
> -???????????????break;
> ????????}
> ????????return data;
> ?}
-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat