Messages in this thread | | | Date | Mon, 22 Jul 2013 22:52:44 +0400 | From | Sergei Shtylyov <> | Subject | Re: [PATCH 15/16] dmaengine: add transfered member to dma_async_tx_descriptor |
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On 07/22/2013 10:10 PM, Sebastian Andrzej Siewior wrote:
> In USB RX path it is possible that the we receive less bytes than > requested. Take the following example: > The driver for USB-to-UART submits an URB with 256 bytes in size and the > dmaengine driver in turn programs a transfer of 256 bytes. The transfer > is programmed and the dma engine waits for the data to arrive. Once data > is sent on the UART the dma engine begins to move data. If there was > only one data byte in the USB packet received then the DMA engine will > only move one byte due to USB restrictions / rules. The real size of the > transfer has to be notified to the user / caller so he set this to the > caller. > This patch adds the transfered member to the dma_async_tx_descriptor > where the caller can obtain the final size.
> Cc: Vinod Koul <vinod.koul@intel.com> > Cc: Dan Williams <djbw@fb.com> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > include/linux/dmaengine.h | 3 +++ > 1 file changed, 3 insertions(+)
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h > index cb286b1..c3a4635 100644 > --- a/include/linux/dmaengine.h > +++ b/include/linux/dmaengine.h > @@ -403,6 +403,8 @@ typedef void (*dma_async_tx_callback)(void *dma_async_param); > * @tx_submit: set the prepared descriptor(s) to be executed by the engine > * @callback: routine to call after this operation is complete > * @callback_param: general parameter to pass to the callback routine > + * @transfered: number of bytes that were really transfered in case the channel > + * transfered less than requested. > * ---async_tx api specific fields--- > * @next: at completion submit this descriptor > * @parent: pointer to the next level up in the dependency chain > @@ -416,6 +418,7 @@ struct dma_async_tx_descriptor { > dma_cookie_t (*tx_submit)(struct dma_async_tx_descriptor *tx); > dma_async_tx_callback callback; > void *callback_param; > + unsigned int transfered;
Correct grammar is "transferred".
WBR, Sergei
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