Re: [git:v4l-dvb/for_v3.6] [media] stv090x: variable 'no_signal' set but not used

Re: [git:v4l-dvb/for_v3.6] [media] stv090x: variable 'no_signal' set but not used

[Peter Senna Tschudin]

Manu,

On Wed, Jun 27, 2012 at 9:59 AM, Manu Abraham <abraham.manu@gmail.com> wrote:
> Wonderful, instead of ignoring the return value, you ignored the whole
> function
> itself. Most of the demodulator registers are R-M-x registers. The patch
> brings
> in unwanted side-effects of R-M-x.

Sorry for that. I'll send V2 of this patch just ignoring the return
value. Can you please send me some reference about R-M-x registers?

>
> Please revert this patch.
>
> Thanks,
> Manu

Thanks,

Peter

>
>
> On Fri, Jun 22, 2012 at 2:28 AM, Mauro Carvalho Chehab <mchehab@redhat.com>
> wrote:
>>
>> This is an automatic generated email to let you know that the following
>> patch were queued at the
>> http://git.linuxtv.org/media_tree.git tree:
>>
>> Subject: [media] stv090x: variable 'no_signal' set but not used
>> Author:  Peter Senna Tschudin <peter.senna@gmail.com>
>> Date:    Thu Jun 14 13:58:15 2012 -0300
>>
>> Tested by compilation only.
>>
>> Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
>> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
>>
>>  drivers/media/dvb/frontends/stv090x.c |    7 +++----
>>  1 files changed, 3 insertions(+), 4 deletions(-)
>>
>> ---
>>
>>
>> http://git.linuxtv.org/media_tree.git?a=commitdiff;h=59f6a93fae656409042c8a55e8b9088893c40378
>>
>> diff --git a/drivers/media/dvb/frontends/stv090x.c
>> b/drivers/media/dvb/frontends/stv090x.c
>> index d79e69f..d229dba 100644
>> --- a/drivers/media/dvb/frontends/stv090x.c
>> +++ b/drivers/media/dvb/frontends/stv090x.c
>> @@ -3172,7 +3172,7 @@ static enum stv090x_signal_state stv090x_algo(struct
>> stv090x_state *state)
>>        enum stv090x_signal_state signal_state = STV090x_NOCARRIER;
>>        u32 reg;
>>        s32 agc1_power, power_iq = 0, i;
>> -       int lock = 0, low_sr = 0, no_signal = 0;
>> +       int lock = 0, low_sr = 0;
>>
>>        reg = STV090x_READ_DEMOD(state, TSCFGH);
>>        STV090x_SETFIELD_Px(reg, RST_HWARE_FIELD, 1); /* Stop path 1 stream
>> merger */
>> @@ -3411,10 +3411,9 @@ static enum stv090x_signal_state
>> stv090x_algo(struct stv090x_state *state)
>>                        /* Reset the packet Error counter2 */
>>                        if (STV090x_WRITE_DEMOD(state, ERRCTRL2, 0xc1) < 0)
>>                                goto err;
>> -               } else {
>> +               } else
>>                        signal_state = STV090x_NODATA;
>> -                       no_signal = stv090x_chk_signal(state);
>> -               }
>> +
>>        }
>>        return signal_state;
>>
>>
>> _______________________________________________
>> linuxtv-commits mailing list
>> linuxtv-commits@linuxtv.org
>> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linuxtv-commits
>
>



-- 
Peter Senna Tschudin
peter.senna@gmail.com
gpg id: 48274C36

Re: [git:v4l-dvb/for_v3.6] [media] stv090x: variable 'no_signal' set but not used

[Manu Abraham]

Hi,

On Wed, Jun 27, 2012 at 8:57 PM, Peter Senna Tschudin
<peter.senna@gmail.com> wrote:
>
> Manu,
>
> On Wed, Jun 27, 2012 at 9:59 AM, Manu Abraham <abraham.manu@gmail.com> wrote:
> > Wonderful, instead of ignoring the return value, you ignored the whole
> > function
> > itself. Most of the demodulator registers are R-M-x registers. The patch
> > brings
> > in unwanted side-effects of R-M-x.
>
> Sorry for that. I'll send V2 of this patch just ignoring the return
> value. Can you please send me some reference about R-M-x registers?
>


Unfortunately public versions of the document do not exist. But, basically the
demodulator is a device that has microcontrollers, memory banks FPGA/DSP
on it.  Specifically, this demodulator is a bit complex device in all
aspects. The
registers what you see externally have different operating modes associated
with it, such as Read-Only, Write-Only, Read-Modify-Write and some others
where they shouldn't be accessed during certain operations and some others
should be updated, such as simple read to update the interface registers, or
in some cases a write of the same value to trigger some states. Even more
complex are the updates which are triggered based on bit-order-significance.
To summarize, the interface registers are shadowed by the on-chip
microcontroller to implement a Wait Free Synchronization method.

I was able to find a related description elsewhere on the Internet.

http://www.patentstorm.us/patents/4342079.html

Hope it helps,

Regards,
Manu