Re: bug in changeset 13239:54535665f94b ?

[e9hack <e9hack@googlemail.com>]

Mauro Carvalho Chehab schrieb:
> Em Sat, 07 Nov 2009 15:05:02 +0100
> e9hack <e9hack@googlemail.com> escreveu:
> 
>> Mauro Carvalho Chehab schrieb:
>>
>>> I agree. We need first to stop DMA activity, and then release the page tables.
>>>
>>> Could you please test if the enclosed patch fixes the issue?
>> Hi Mauro,
>>
>> your patch doesn't solve the problem, because saa7146_dma_free() doesn't stop a running
>> dma transfer of the saa7146.
> 
> Well, it should be stopping it. The logic is to wait for an incoming dma
> transfer and then disable dma transfers:
> 
> void saa7146_dma_free(struct saa7146_dev *dev,struct videobuf_queue *q,
>                                                 struct saa7146_buf *buf)
> {
>         struct videobuf_dmabuf *dma=videobuf_to_dma(&buf->vb);
>         DEB_EE(("dev:%p, buf:%p\n",dev,buf));
> 
>         BUG_ON(in_interrupt());
> 
>         videobuf_waiton(&buf->vb,0,0);
>         videobuf_dma_unmap(q, dma);
>         videobuf_dma_free(dma);
>         buf->vb.state = VIDEOBUF_NEEDS_INIT;
> }

In my case, videobuf_queue_cancel() is called previously. videobuf_queue_cancel() wakes up
all buffers, but it doesn't handle the currently by the saa7146 used buffer. queue->curr
points to this buffer. Waiting for an incoming dma transfer in saa7146_dma_free() has no
effect for such a buffer.

Regards,
Hartmut