Re: [PATCH v2] stb0899: Fix slow and not locking DVB-S transponder(s)

[Lutz Sammer <johns98@gmx.net>]

On 10/06/11 20:56, Manu Abraham wrote:
> Mauro,
>
> comments in-line.
>
> On Sat, Oct 1, 2011 at 12:28 AM, Mauro Carvalho Chehab
> <mchehab@redhat.com>  wrote:
>> Em 30-09-2011 15:41, Lutz Sammer escreveu:
>>> On 09/30/11 19:07, Mauro Carvalho Chehab wrote:
>>>> Em 29-09-2011 18:22, Lutz Sammer escreveu:
>>>>> Another version of
>>>>> http://patchwork.linuxtv.org/patch/6307
>>>>> http://patchwork.linuxtv.org/patch/6510
>>>>> which was superseded or rejected, but I don't know why.
>>>>
>>>> Probably because of the same reason of this patch [1]:
>>>>
>>>> patch -p1 -i patches/lmml_8023_v2_stb0899_fix_slow_and_not_locking_dvb_s_transponder_s.patch --dry-run -t -N
>>>> patching file drivers/media/dvb/frontends/stb0899_algo.c
>>>> Hunk #1 FAILED at 358.
>>>> 1 out of 1 hunk FAILED -- saving rejects to file drivers/media/dvb/frontends/stb0899_algo.c.rej
>>>>    drivers/media/dvb/frontends/stb0899_algo.c |    1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> I'll mark this one as rejected, as it doesn't apply upstream[2].
>>>>
>>>> [1] http://patchwork.linuxtv.org/patch/8023/
>>>> [2] at tree/branch: git://linuxtv.org/media_tree.git staging/for_v3.2
>>>>
>>>> Please test if the changes made upstream to solve a similar trouble fixes your issue.
>>>> If not, please rebase your patch on the top of it and resend.
>>>>
>>>> Thanks,
>>>> Mauro
>>>>>
>>>>> In stb0899_status stb0899_check_data the first read of STB0899_VSTATUS
>>>>> could read old (from previous search) status bits and the search fails
>>>>> on a good frequency.
>>>>>
>>>>> With the patch more transponder could be locked and locks about 2* faster.
>>
>> Manu,
>>
>> Could you please review this one-line patch?
>>
>>
>>>>>
>>>>> Signed-off-by: Lutz Sammer<johns98@gmx.net>
>>>>> ---
>>>>>    drivers/media/dvb/frontends/stb0899_algo.c |    1 +
>>>>>    1 files changed, 1 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/drivers/media/dvb/frontends/stb0899_algo.c b/drivers/media/dvb/frontends/stb0899_algo.c
>>>>> index d70eee0..8eca419 100644
>>>>> --- a/drivers/media/dvb/frontends/stb0899_algo.c
>>>>> +++ b/drivers/media/dvb/frontends/stb0899_algo.c
>>>>> @@ -358,6 +358,7 @@ static enum stb0899_status stb0899_check_data(struct stb0899_state *state)
>>>>>           else
>>>>>                   dataTime = 500;
>>>>>
>>>>> +       stb0899_read_reg(state, STB0899_VSTATUS); /* clear old status bits */
>>>>>           stb0899_write_reg(state, STB0899_DSTATUS2, 0x00); /* force search loop */
>>>>>           while (1) {
>>>>>                   /* WARNING! VIT LOCKED has to be tested before VIT_END_LOOOP   */
>>
>
> Please add in these comments, in case you want to apply the change. I
> am neither for the patch, nor against it.
>
> - In fact, it doesn't hurt to read STATUS just before LOCK test.
> - I wasn't able to find any noticeable difference in LOCK acquisition.
> - Nowhere, I was able to find that reading VSTATUS, clears the
> Read-Only bits set by the onchip microcontroller. The above comment
> could be wrong at least, as far as I can say.
>
> But that said, if the change does really help (thinking of strange
> issues with some Silicon cuts)
>
> Acked-by: Manu Abraham<manu@linuxtv.org>
>
> Regards,
> Manu
>

To be exact only the loop bit is reset by the read:

kernel: [62791.427869] stb0899: vstatus 40 00 40 00
kernel: [62791.597609] stb0899: vstatus 00 00 18 18

Printed twice before and after the loop. I tested this with the
tt-3600 and tt-3650.

Johns