[media] mxl111sf: Check return value in mxl111sf_config_mpeg_in

Error check after mxl111sf_read_reg

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 4c66c9205c07 ("[media] dvb-usb: add ATSC support for the Hauppauge WinTV-Aero-M")
Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
---
 drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Hi,
On Fri, Dec 23, 2022 at 07:28:47AM -0500, Michael Ira Krufky wrote:
> On Thu, Dec 22, 2022, 4:46 PM Artem Chernyshev <artem.chernyshev@red-soft.ru>
> wrote:
> 
> > Error check after mxl111sf_read_reg
> >
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >
> > Fixes: 4c66c9205c07 ("[media] dvb-usb: add ATSC support for the Hauppauge
> > WinTV-Aero-M")
> > Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
> > ---
> >  drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
> > b/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
> > index 40b26712ba4c..ad1888514bd0 100644
> > --- a/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
> > +++ b/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
> > @@ -121,7 +121,8 @@ int mxl111sf_config_mpeg_in(struct mxl111sf_state
> > *state,
> >         mxl_fail(ret);
> >
> >         /* Configure MPEG Clock phase */
> > -       mxl111sf_read_reg(state, V6_MPEG_IN_CLK_INV_REG, &mode);
> > +       ret = mxl111sf_read_reg(state, V6_MPEG_IN_CLK_INV_REG, &mode);
> > +       mxl_fail(ret);
> >
> >         if (clock_phase == TSIF_NORMAL)
> >                 mode &= ~V6_INVERTED_CLK_PHASE;
> > --
> > 2.30.3
> >
> 
> Artem,
> 
> Thank you for this.  If I recall correctly, the read from that particular
> register often returns a failure despite the correct value being read into
> memory. This needs to be tested before being merged, and if my memory is
> correct about this we should add a comment about it. Unfortunately, I'm out
> of town at the moment, I won't be able to test this for some time. Can we
> hold off on this one for a bit? If you don't hear from me after a few
> weeks, please feel free to ping me again. Thanks.
> 
> Best,
> Michael Krufky
> 
> >

Thanks for reply. I'll be waiting for your decision

Best regards,
Artem

On 23/12/2022 17:28, Artem Chernyshev wrote:
> Hi,
> On Fri, Dec 23, 2022 at 07:28:47AM -0500, Michael Ira Krufky wrote:
>> On Thu, Dec 22, 2022, 4:46 PM Artem Chernyshev <artem.chernyshev@red-soft.ru>
>> wrote:
>>
>>> Error check after mxl111sf_read_reg
>>>
>>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>>
>>> Fixes: 4c66c9205c07 ("[media] dvb-usb: add ATSC support for the Hauppauge
>>> WinTV-Aero-M")
>>> Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
>>> ---
>>>  drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
>>> b/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
>>> index 40b26712ba4c..ad1888514bd0 100644
>>> --- a/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
>>> +++ b/drivers/media/usb/dvb-usb-v2/mxl111sf-phy.c
>>> @@ -121,7 +121,8 @@ int mxl111sf_config_mpeg_in(struct mxl111sf_state
>>> *state,
>>>         mxl_fail(ret);
>>>
>>>         /* Configure MPEG Clock phase */
>>> -       mxl111sf_read_reg(state, V6_MPEG_IN_CLK_INV_REG, &mode);
>>> +       ret = mxl111sf_read_reg(state, V6_MPEG_IN_CLK_INV_REG, &mode);
>>> +       mxl_fail(ret);
>>>
>>>         if (clock_phase == TSIF_NORMAL)
>>>                 mode &= ~V6_INVERTED_CLK_PHASE;
>>> --
>>> 2.30.3
>>>
>>
>> Artem,
>>
>> Thank you for this.  If I recall correctly, the read from that particular
>> register often returns a failure despite the correct value being read into
>> memory. This needs to be tested before being merged, and if my memory is
>> correct about this we should add a comment about it. Unfortunately, I'm out
>> of town at the moment, I won't be able to test this for some time. Can we
>> hold off on this one for a bit? If you don't hear from me after a few
>> weeks, please feel free to ping me again. Thanks.
>>
>> Best,
>> Michael Krufky
>>
>>>
> 
> Thanks for reply. I'll be waiting for your decision

I'll drop this patch, I never saw a follow-up on this.

If this is really needed, then just resend.

Regards,

	Hans

> 
> Best regards,
> Artem