2021-05-19 19:11:02

by Rajat Asthana

[permalink] [raw]
Subject: [PATCH] greybus: audio: Fix sparse warning.

Enforce int type on SNDRV_CTL_ELEM_IFACE_MIXER to fix sparse warning:
> warning: restricted snd_ctl_elem_iface_t degrades to integer

The iface field in the gb_audio_control struct is of type __u8, but the
values stored in it are of type int. So on conversion they are degraded.
Adding (__force int) will enforce them not to be degraded.

Signed-off-by: Rajat Asthana <[email protected]>
---
drivers/staging/greybus/audio_topology.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c
index 1fc7727ab7be..1e613d42d823 100644
--- a/drivers/staging/greybus/audio_topology.c
+++ b/drivers/staging/greybus/audio_topology.c
@@ -676,7 +676,7 @@ static int gbaudio_tplg_create_kcontrol(struct gbaudio_module_info *gb,
struct gbaudio_ctl_pvt *ctldata;

switch (ctl->iface) {
- case SNDRV_CTL_ELEM_IFACE_MIXER:
+ case (__force int)SNDRV_CTL_ELEM_IFACE_MIXER:
switch (ctl->info.type) {
case GB_AUDIO_CTL_ELEM_TYPE_ENUMERATED:
ret = gbaudio_tplg_create_enum_kctl(gb, kctl, ctl);
@@ -903,7 +903,7 @@ static int gbaudio_tplg_create_wcontrol(struct gbaudio_module_info *gb,
int ret;

switch (ctl->iface) {
- case SNDRV_CTL_ELEM_IFACE_MIXER:
+ case (__force int)SNDRV_CTL_ELEM_IFACE_MIXER:
switch (ctl->info.type) {
case GB_AUDIO_CTL_ELEM_TYPE_ENUMERATED:
ret = gbaudio_tplg_create_enum_ctl(gb, kctl, ctl);
--
2.31.1



2021-05-19 19:27:47

by Dan Carpenter

[permalink] [raw]
Subject: Re: [PATCH] greybus: audio: Fix sparse warning.

On Wed, May 19, 2021 at 09:46:24AM +0530, Rajat Asthana wrote:
> Enforce int type on SNDRV_CTL_ELEM_IFACE_MIXER to fix sparse warning:
> > warning: restricted snd_ctl_elem_iface_t degrades to integer
>
> The iface field in the gb_audio_control struct is of type __u8, but the
> values stored in it are of type int. So on conversion they are degraded.
> Adding (__force int) will enforce them not to be degraded.
>

The patch is fine, but the commit message is not very great. This
patch doesn't "enforce" anything or affect the compiled code at all,
it just silences a Sparse warning. Here is a better commit message.

Sparse complains that:

warning: restricted snd_ctl_elem_iface_t degrades to integer

I have looked at this code, and the code is fine as-is. Normally
we would frown on using the __force directive to silence Sparse
warnings but in this case it's fine. Case statements can't be
made into __bitwise types. We also can't change the type of
"ctl->iface" either because that is part of the user space API.

So just add a (__force int) to make the warning go away.

regards,
dan carpenter


2021-05-19 19:38:35

by Rajat Asthana

[permalink] [raw]
Subject: [PATCH v2] greybus: audio: Fix sparse warning.

Sparse complains that:
warning: restricted send_ctl_elem_iface_t degrades to integer.

I have looked at this code, and the code is fine as-is. Normally we
would frown on using the __force directive to silence Sparse warnings
but in this case it's fine. Case statements can't be made into __bitwise
types. We also can't change the type of "ctl->iface" either because that
is part of the user space API.

So just add a (__force int) to make the warning go away.

Signed-off-by: Rajat Asthana <[email protected]>
---
Changes in v2:
- Update the commit message.

drivers/staging/greybus/audio_topology.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c
index 1fc7727ab7be..1e613d42d823 100644
--- a/drivers/staging/greybus/audio_topology.c
+++ b/drivers/staging/greybus/audio_topology.c
@@ -676,7 +676,7 @@ static int gbaudio_tplg_create_kcontrol(struct gbaudio_module_info *gb,
struct gbaudio_ctl_pvt *ctldata;

switch (ctl->iface) {
- case SNDRV_CTL_ELEM_IFACE_MIXER:
+ case (__force int)SNDRV_CTL_ELEM_IFACE_MIXER:
switch (ctl->info.type) {
case GB_AUDIO_CTL_ELEM_TYPE_ENUMERATED:
ret = gbaudio_tplg_create_enum_kctl(gb, kctl, ctl);
@@ -903,7 +903,7 @@ static int gbaudio_tplg_create_wcontrol(struct gbaudio_module_info *gb,
int ret;

switch (ctl->iface) {
- case SNDRV_CTL_ELEM_IFACE_MIXER:
+ case (__force int)SNDRV_CTL_ELEM_IFACE_MIXER:
switch (ctl->info.type) {
case GB_AUDIO_CTL_ELEM_TYPE_ENUMERATED:
ret = gbaudio_tplg_create_enum_ctl(gb, kctl, ctl);
--
2.31.1


2021-05-19 21:16:00

by Dan Carpenter

[permalink] [raw]
Subject: Re: [PATCH v2] greybus: audio: Fix sparse warning.

On Wed, May 19, 2021 at 07:11:19PM +0530, Rajat Asthana wrote:
> Sparse complains that:
> warning: restricted send_ctl_elem_iface_t degrades to integer.
>
> I have looked at this code, and the code is fine as-is. Normally we
> would frown on using the __force directive to silence Sparse warnings
> but in this case it's fine. Case statements can't be made into __bitwise
> types. We also can't change the type of "ctl->iface" either because that
> is part of the user space API.
>
> So just add a (__force int) to make the warning go away.
>
> Signed-off-by: Rajat Asthana <[email protected]>
> ---
> Changes in v2:
> - Update the commit message.

Thanks!

Reviewed-by: Dan Carpenter <[email protected]>

regards,
dan carpenter