On 29.01.2013 12:02, Andrew Lunn wrote:
Now I activated the debug messages in em28xx. From the messages I see no correlation of the pool exhaustion and lost sync. Also I cannot see any error messages from the em28xx driver. I see a lot of init_isoc/stop_urbs (maybe EPG scan?) without draining the coherent pool (checked with 'cat /debug/dma-api/num_free_entries', which gave stable numbers), but after half an hour there are only init_isoc messages without corresponding stop_urbs messages and num_free_entries decreased until coherent pool exhaustion.Hi Soeren em28xx_stop_urbs() is only called by em28xx_stop_streaming(). em28xx_stop_streaming() is only called by em28xx_stop_feed() when 0 == dvb->nfeeds. em28xx_stop_feed()and em28xx_start_feed() look O.K, dvb->nfeeds is protected by a mutex etc. Now, em28xx_init_isoc() is also called by buffer_prepare(). This uses em28xx_alloc_isoc() to do the actual allocation, and that function sets up the urb such that on completion the function em28xx_irq_callback() is called. It looks like there might be issues here: Once the data has been copied out, it resubmits the urb: urb->status = usb_submit_urb(urb, GFP_ATOMIC); if (urb->status) { em28xx_isocdbg("urb resubmit failed (error=%i)\n", urb->status); } However, if the ubs_submit_urb fails, it looks like the urb is lost. If you look at other code submitting urbs you have this pattern: rc = usb_submit_urb(isoc_bufs->urb[i], GFP_ATOMIC); if (rc) { em28xx_err("submit of urb %i failed (error=%i)\n", i, rc); em28xx_uninit_isoc(dev, mode); return rc; } Do you have your build such that you would see "urb resubmit failed" in your logs? Are there any?
I only had "urb resubmit failed" messages _after_ the coherent pool exhaustion. So I guess something below the usb_submit_urb call is allocating (too much) memory, sometimes. Or can dvb_demux allocate memory and blame orion-ehci for it?
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