Messages in this thread | | | Date | Tue, 14 Sep 2010 21:51:09 +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.
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.
>> 'ís_dma' condition above the patched code:
>> if (is_dma || request->actual == request->length) {
>> and then it will hit the code sending the final ZLP (above this >> patched code too):
> but this was already there before the patch.
Yes, and here lies the problem.
>> /* >> * First, maybe a terminating short packet. >> Some DMA >> * engines might handle this by themselves. >> */ >> if ((request->zero && request->length >> && request->length % >> musb_ep->packet_sz == 0) >> #ifdef CONFIG_USB_INVENTRA_DMA >> || (is_dma && (!dma->desired_mode || >> (request->actual & >> (musb_ep->packet_sz - >> 1)))) >> #endif >> ) {
>> before the transfer is complete while it should only be hit when and >> only when >> the whole transfer is complete. The current code doesn't look correct >> as well >> though, all due to this 'ís_dma' condition. Surely this needs fixing.
> 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?
> the problem is not on the extra if () added below the quoted code, > it's on the quoted code itself, which wasn't changed in any way.
Let me repeat: in the PIO mode the added check is just duplicate, in the DMA mode it's added too late in the code, after ZLP/short packet send is triggered. We should modify the check at the top of that code instead.
WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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