[PATCH] greybus: audio: Fix sparse warning.

[PATCH] greybus: audio: Fix sparse warning.

[Rajat Asthana]

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 <thisisrast7@gmail.com>
---
 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

Re: [PATCH] greybus: audio: Fix sparse warning.

[Dan Carpenter]

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

[PATCH v2] greybus: audio: Fix sparse warning.

[Rajat Asthana]

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 <thisisrast7@gmail.com>
---
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

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

[Dan Carpenter]

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 <thisisrast7@gmail.com>
> ---
> Changes in v2:
>     - Update the commit message.

Thanks!

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>

regards,
dan carpenter