From: Lars-Peter Clausen <lars@metafoo.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
balbi@ti.com, george.cherian@ti.com,
Vinod Koul <vinod.koul@intel.com>, Dan Williams <djbw@fb.com>
Subject: Re: [PATCH 15/16] dmaengine: add transfered member to dma_async_tx_descriptor
Date: Thu, 25 Jul 2013 16:57:47 +0200 [thread overview]
Message-ID: <51F13CEB.7030408@metafoo.de> (raw)
In-Reply-To: <1374516607-2705-16-git-send-email-bigeasy@linutronix.de>
On 07/22/2013 08:10 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.
I'm not sure that this will work. Once you've submitted the descriptor it is
owned by the dmaengine driver and you are not allowed to dereference it
anymore since the dmaengine driver might free the memory at any time. You
should only reference the descriptor by the cookie returned by submit().
- Lars
next prev parent reply other threads:[~2013-07-25 14:57 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-22 18:09 am33x: multiple instances and dma support, v2 Sebastian Andrzej Siewior
2013-07-22 18:09 ` [PATCH 01/16] usb: musb: dsps: init / shutdown the phy Sebastian Andrzej Siewior
2013-07-25 14:32 ` Felipe Balbi
2013-07-22 18:09 ` [PATCH 02/16] usb: phy: phy-nop: add support for am335x PHY Sebastian Andrzej Siewior
2013-07-25 14:33 ` Felipe Balbi
2013-07-25 14:45 ` Sebastian Andrzej Siewior
2013-07-25 14:54 ` Felipe Balbi
2013-07-22 18:09 ` [PATCH 03/16] usb: musb: dsps: remove the hardcoded phy pieces Sebastian Andrzej Siewior
2013-07-22 18:09 ` [PATCH 04/16] usb: musb: remove ti81xx pieces from musb Sebastian Andrzej Siewior
2013-07-22 18:09 ` [PATCH 05/16] usb: musb: dsps: use proper child nodes Sebastian Andrzej Siewior
2013-07-23 6:46 ` George Cherian
2013-07-23 9:15 ` Sebastian Andrzej Siewior
2013-07-22 18:09 ` [PATCH 06/16] usb: musb: dsps: rename ti81xx_driver_data to am33xx_driver_data Sebastian Andrzej Siewior
2013-07-23 6:04 ` George Cherian
2013-07-23 9:09 ` Sebastian Andrzej Siewior
2013-07-23 9:14 ` George Cherian
[not found] ` <CADYTM3avh7GFTDQW01FnojKZkmL0_hi+=K-VVwCw5peJL2hwTA@mail.gmail.com>
2013-07-23 19:09 ` Bin Liu
2013-07-25 14:41 ` Sebastian Andrzej Siewior
2013-07-25 15:12 ` Bin Liu
2013-07-25 15:16 ` Sebastian Andrzej Siewior
2013-07-25 15:28 ` Bin Liu
2013-07-25 16:11 ` Felipe Balbi
2013-07-26 9:11 ` [PATCH 06/16 => 1/2] " Sebastian Andrzej Siewior
2013-07-26 9:11 ` [PATCH 06/16 => 2/2] usb: musb: dsps: remove EOI access Sebastian Andrzej Siewior
2013-07-25 15:37 ` [PATCH 06/16] usb: musb: dsps: rename ti81xx_driver_data to am33xx_driver_data Felipe Balbi
2013-07-22 18:09 ` [PATCH 07/16] usb: musb: replace ifndef with ifdef for CONFIG_MUSB_PIO_ONLY Sebastian Andrzej Siewior
2013-07-22 18:09 ` [PATCH 08/16] usb: musb: dma: merge ->start/stop into create/destroy Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 09/16] usb: musb: provide empty dma_controller_create() in PIO mode Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 10/16] usb: musb: remove a few is_dma_capable() in init/exit code Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 11/16] usb: musb: core: call dma_controller_destroy() in the err path Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 12/16] usb: musb: unmap reqs in musb_gadget_queue()'s error case Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 13/16] usb: musb: do not change dev's dma_mask Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 14/16] usb: musb: dsps: add MUSB_DEVCTL_SESSION back after removal Sebastian Andrzej Siewior
[not found] ` <CADYTM3a5xzs+-VCTeKLGiRjo7JOqOJ5H4EWDACpTMovY5_ooRA@mail.gmail.com>
2013-07-23 17:31 ` Sebastian Andrzej Siewior
2013-07-23 18:55 ` Bin Liu
2013-07-26 15:44 ` Sebastian Andrzej Siewior
2013-07-26 16:31 ` Sebastian Andrzej Siewior
2013-07-26 17:53 ` Bin Liu
2013-07-26 18:17 ` Bin Liu
2013-07-26 18:22 ` Sebastian Andrzej Siewior
2013-07-26 18:29 ` Bin Liu
2013-07-26 19:55 ` Sebastian Andrzej Siewior
2013-07-26 20:15 ` Bin Liu
2013-07-26 20:35 ` Sebastian Andrzej Siewior
2013-07-27 3:07 ` Bin Liu
2013-07-29 16:53 ` Sebastian Andrzej Siewior
2013-07-29 17:26 ` Bin Liu
2013-07-29 17:51 ` Sebastian Andrzej Siewior
2013-07-29 18:41 ` Bin Liu
2013-08-09 16:03 ` [PATCH] usb: musb: am335x: Do not remove the session bin HOST-only mode Sebastian Andrzej Siewior
2013-08-09 20:30 ` Sergei Shtylyov
2013-08-13 7:14 ` Sebastian Andrzej Siewior
2013-08-13 13:03 ` Bin Liu
2013-08-13 13:17 ` Sebastian Andrzej Siewior
2013-08-13 13:33 ` Bin Liu
2013-08-13 13:44 ` Sebastian Andrzej Siewior
2013-08-13 14:01 ` Bin Liu
2013-08-13 14:23 ` Sebastian Andrzej Siewior
2013-08-13 14:32 ` Bin Liu
2013-08-14 18:17 ` Sebastian Andrzej Siewior
2013-08-14 18:43 ` Bin Liu
2013-07-22 18:10 ` [PATCH 15/16] dmaengine: add transfered member to dma_async_tx_descriptor Sebastian Andrzej Siewior
2013-07-22 18:52 ` Sergei Shtylyov
2013-07-23 17:12 ` Sebastian Andrzej Siewior
2013-07-25 14:57 ` Lars-Peter Clausen [this message]
2013-07-25 15:12 ` Sebastian Andrzej Siewior
2013-07-25 15:32 ` Lars-Peter Clausen
2013-07-26 9:30 ` Sebastian Andrzej Siewior
2013-07-29 11:39 ` Vinod Koul
2013-07-29 12:33 ` Sebastian Andrzej Siewior
2013-07-22 18:10 ` [PATCH 16/16] usb/musb dma: add cppi41 dma driver Sebastian Andrzej Siewior
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