[pvrusb2] changing capture resolution bug

[Mike Isely]

There appears to be a problem in the pvrusb2 driver involving setting the 
capture resolution and it is specific to 24xxx devices.  I looked into 
this a bit tonight.  First, the VIDIOC_S_FMT cleanup I did is not at fault 
- that code appears to be working as intended.

The problem right now is that setting any horizontal capture resolution 
other than 720 results in trashed video (green bars, "screen door" effect, 
among other things).

The problem only seems to happen on 24xxx devices; 29xxx devices are not 
affected.

I chased through the pvrusb2 driver; it doesn't really care about 
resolution choices but instead just passes that information to the 
appropriate modules.  Best I can tell is that the info is indeed making it 
to the cx25840 module (which is used for 24xxx devices but not 29xxx 
devices).  At this point I'm suspecting a problem in the cx25840 module 
but it's too early to really be sure.

In the mean time if you have a 24xxx device, make SURE you are using a 
horizontal capture resolution of 720 (using whatever method is appropriate 
for the app in question).  If for example you have MythTV configured to 
capture at 640x480 and you are using a 24xxx device, then you are going to 
have problems.  (And if you don't, then I definitely want to hear about 
it.)

I strongly believe now that Renan got past this problem in MythTV because 
by moving to the earlier pvrusb2 snapshot he reverted to logic which had 
the broken VIDIOC_S_FMT implementation - which means that the pvrusb2 
driver was going to capture at 720x480 regardless of what MythTV might 
have asked for.  An alternative and less drastic workaround is just to 
change the MythTV capture resolution to 720 horizontal.  So what Renan has 
is a workaround, while the root cause still hasn't been solved.

If anyone sees any behavior that looks related to this issue and conflicts 
with what I'm saying here, please speak up so I can add more pieces to 
this puzzle...

   -Mike


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