Messages in this thread | | | Date | Tue, 29 Jan 2013 12:50:04 +0100 | From | Soeren Moch <> | Subject | Re: [PATCH v2] mm: dmapool: use provided gfp flags for all dma_alloc_coherent() calls |
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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?
Soeren
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