Messages in this thread | | | Date | Wed, 15 Sep 2010 14:01:05 +0400 | From | Sergei Shtylyov <> | Subject | Re: [RESEND/PATCH 5/6] USB: musb-gadget: complete request only if data is transfered over |
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Hello.
On 15-09-2010 10:53, Felipe Balbi wrote:
>>>> If a DMA interrupt comes when the whole transfer is not yet >>>> complete (and >>>> other Ming Lei's patches are making this possible),
>> Oh, here I mixed some other patch with Ming Lei's ones...
>>>> it will pass due to the
>>> than this is the actual problem, no ? If we're using mode1 dma (as we >>> are on tx path), we should only get dma interrupt when the whole >>> transfer has been completed.
>> The Inventra DMA controller has serious DMA length limitation, so the whole >> transfer may take more than one DMA.
> When I said 'whole transfer' I meant the transfer size you programmed > dma to transfer, see that we have (not actual code):
> if (transfer_size > dma->max_len) > transfer_size = dma->max_len;
> dma->channel_program(...,..., transfer_size,...);
Ah, I didn't mean the same thing -- I meant the transfer size as specified by 'struct usb_request'.
> with mode1, we will only get irq when dma has transferred transfer_size > bytes.
Sure.
>>> likewise, this was there before the patch. I don't think the real >>> problem lies with this patch, it's been there for a while, don't you >>> agree ?
>> Then what problem this patch fixes, if not this one?
> if request->length == 1MB and dma->max_len = 128KB, when is_dma is true, > request->actual will be different from request->length for 7 > 'iterations', then only on the 8th it will be the same. I believe that's > what Ming is trying to fix.
I repeat once again: it's too late to check this where Ming is inserting the check.
> Ming, am I correct ? > >> Let me repeat: in the PIO mode the added check is just duplicate, in the DMA
> it is duplicate for PIO, but not for DMA.
I didn't say it was duplicate for DMA, just too late.
WBR, Sergei
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