em28xx submit of urb 0 failed (error=-27)

Do you have any idea about that bug?
kernel: submit of urb 0 failed (error=-27)

https://bugzilla.kernel.org/show_bug.cgi?id=72891

I have seen it recently very often when I try start streaming DVB. When it happens, device is unusable. I have feeling that it could be coming from recent 28xx big changes where it was modularised. IIRC I reported that at the time and Mauro added error number printing to log entry. Anyhow, it is very annoying and occurs very often. And people have started pinging me as I have added very many DVB devices to em28xx.

regards
Antti

I just ran blind scan using w_scan and it interrupted scanning, with following error (ioctl DMX_SET_FILTER failed: 27 File too large).

602000: (time: 00:58.973)

         (0.308sec): SCL (0x1F)
         (0.308sec) signal
         (0.308sec) lock
         signal ok:	QAM_AUTO f = 602000 kHz I999B8C999D999T999G999Y999 

(0:0:0)
initial PAT lookup..
start_filter:1644: ERROR: ioctl DMX_SET_FILTER failed: 27 File too large

regards
Antti

Quoted 11 lines · Antti Palosaari

Do you have any idea about that bug?
kernel: submit of urb 0 failed (error=-27)

https://bugzilla.kernel.org/show_bug.cgi?id=72891

I have seen it recently very often when I try start streaming DVB. When it happens, device is unusable. I have feeling that it could be coming from recent 28xx big changes where it was modularised. IIRC I reported that at the time and Mauro added error number printing to log entry. Anyhow, it is very annoying and occurs very often. And people have started pinging me as I have added very many DVB devices to em28xx.

From what I know, different versions of em28xx chips have different

Em Thu, 12 Jun 2014 03:37:26 +0300
Antti Palosaari <[email protected]> escreveu:

Quoted 12 lines

I just ran blind scan using w_scan and it interrupted scanning, with following error (ioctl DMX_SET_FILTER failed: 27 File too large).

602000: (time: 00:58.973)

          (0.308sec): SCL (0x1F)
          (0.308sec) signal
          (0.308sec) lock
          signal ok:	QAM_AUTO f = 602000 kHz I999B8C999D999T999G999Y999

(0:0:0)
initial PAT lookup..
start_filter:1644: ERROR: ioctl DMX_SET_FILTER failed: 27 File too large

Quoted 16 lines

regards
Antti

Quoted 11 lines · Antti Palosaari

Do you have any idea about that bug?
kernel: submit of urb 0 failed (error=-27)

https://bugzilla.kernel.org/show_bug.cgi?id=72891

I have seen it recently very often when I try start streaming DVB. When it happens, device is unusable. I have feeling that it could be coming from recent 28xx big changes where it was modularised. IIRC I reported that at the time and Mauro added error number printing to log entry. Anyhow, it is very annoying and occurs very often. And people have started pinging me as I have added very many DVB devices to em28xx.

Well, according with USB documentation (Documentation/usb/URB.txt), EFBIG means:
- Too many requested ISO frames

Perhaps the logic that calculates the number of URBs has a bug. In the past, the URB size was hardcoded. Nowadays, em28xx dynamically calculate it based on the USB descriptors, and the endpoints found.

From what I know, different versions of em28xx chips have different
max limits. We need to identify on what chip version this error is occurring, and reduce the number of ISOC frames there (with will reduce the max bandwidth supported by such chip).