[PATCH] cx231xx: Increase USB bridge bandwidth

[PATCH] cx231xx: Increase USB bridge bandwidth

[Brad Love]

The cx231xx USB bridge has issue streaming QAM256 DVB-C channels.
QAM64 channels were fine, but QAM256 channels produced corrupted
transport streams.

cx231xx alt mode 4 does not provide enough bandwidth to acommodate
QAM256 DVB-C channels, most likely DVB-T2 channels would break up
as well. Alt mode 5 increases bridge bandwidth to 90Mbps, and
fixes QAM256 DVB-C streaming.

Signed-off-by: Brad Love <brad@nextdimension.cc>
---
 drivers/media/usb/cx231xx/cx231xx-dvb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/cx231xx/cx231xx-dvb.c b/drivers/media/usb/cx231xx/cx231xx-dvb.c
index 7130294..67ed667 100644
--- a/drivers/media/usb/cx231xx/cx231xx-dvb.c
+++ b/drivers/media/usb/cx231xx/cx231xx-dvb.c
@@ -276,7 +276,7 @@ static int start_streaming(struct cx231xx_dvb *dvb)
 
 	if (dev->USE_ISO) {
 		dev_dbg(dev->dev, "DVB transfer mode is ISO.\n");
-		cx231xx_set_alt_setting(dev, INDEX_TS1, 4);
+		cx231xx_set_alt_setting(dev, INDEX_TS1, 5);
 		rc = cx231xx_set_mode(dev, CX231XX_DIGITAL_MODE);
 		if (rc < 0)
 			return rc;
-- 
2.7.4

Re: [PATCH] cx231xx: Increase USB bridge bandwidth

[Matthias Schwarzott]

Am 02.04.2018 um 21:59 schrieb Brad Love:
> The cx231xx USB bridge has issue streaming QAM256 DVB-C channels.
> QAM64 channels were fine, but QAM256 channels produced corrupted
> transport streams.
> 
> cx231xx alt mode 4 does not provide enough bandwidth to acommodate
> QAM256 DVB-C channels, most likely DVB-T2 channels would break up
> as well. Alt mode 5 increases bridge bandwidth to 90Mbps, and
> fixes QAM256 DVB-C streaming.
> 
Hi Brad,

I read through the media commits applied in the last weeks.

This patch looks so simple and yet resolves the (for me) unexplainable
behaviour of the Hauppauge WinTV-HVR-930C-HD. DVB-C reception did only
produce garbage, but the the same demod driver (si2165) does work
perfectly in a PCI device.

Thank you for fixing this issue.

Regards
Matthias

Re: [PATCH] cx231xx: Increase USB bridge bandwidth

[Brad Love]

Hi Matthias,



On 2018-06-05 13:04, Matthias Schwarzott wrote:
> Am 02.04.2018 um 21:59 schrieb Brad Love:
>> The cx231xx USB bridge has issue streaming QAM256 DVB-C channels.
>> QAM64 channels were fine, but QAM256 channels produced corrupted
>> transport streams.
>>
>> cx231xx alt mode 4 does not provide enough bandwidth to acommodate
>> QAM256 DVB-C channels, most likely DVB-T2 channels would break up
>> as well. Alt mode 5 increases bridge bandwidth to 90Mbps, and
>> fixes QAM256 DVB-C streaming.
>>
> Hi Brad,
>
> I read through the media commits applied in the last weeks.
>
> This patch looks so simple and yet resolves the (for me) unexplainable
> behaviour of the Hauppauge WinTV-HVR-930C-HD. DVB-C reception did only
> produce garbage, but the the same demod driver (si2165) does work
> perfectly in a PCI device.
>
> Thank you for fixing this issue.
>
> Regards
> Matthias

Happy to get this fixed for you :) If you know of any other outstanding
issues
with Hauppauge hardware, feel free to point me at them.

Cheers,

Brad