Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933150Ab3GVSwu (ORCPT ); Mon, 22 Jul 2013 14:52:50 -0400 Received: from mail-la0-f51.google.com ([209.85.215.51]:55828 "EHLO mail-la0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932903Ab3GVSws (ORCPT ); Mon, 22 Jul 2013 14:52:48 -0400 Message-ID: <51ED7F7C.2080205@cogentembedded.com> Date: Mon, 22 Jul 2013 22:52:44 +0400 From: Sergei Shtylyov Organization: Cogent Embedded User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: Sebastian Andrzej Siewior CC: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, balbi@ti.com, george.cherian@ti.com, Vinod Koul , Dan Williams Subject: Re: [PATCH 15/16] dmaengine: add transfered member to dma_async_tx_descriptor References: <1374516607-2705-1-git-send-email-bigeasy@linutronix.de> <1374516607-2705-16-git-send-email-bigeasy@linutronix.de> In-Reply-To: <1374516607-2705-16-git-send-email-bigeasy@linutronix.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2302 Lines: 50 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 > Cc: Dan Williams > Signed-off-by: Sebastian Andrzej Siewior > --- > 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 -- 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/