From mboxrd@z Thu Jan  1 00:00:00 1970
From: b32955@freescale.com (Huang Shijie)
Date: Thu, 24 Nov 2011 10:42:42 +0800
Subject: [PATCH] IMX/SDMA : save the real count for one DMA transaction.
In-Reply-To: <1322048442.1516.274.camel@vkoul-udesk3>
References: <1322039585-7901-1-git-send-email-b32955@freescale.com>	
 <20111123105821.GC4063@pengutronix.de> <4ECCD34C.1090400@freescale.com>	
 <20111123110626.GD4063@pengutronix.de> <4ECCD553.5020804@freescale.com>	
 <20111123111816.GF4063@pengutronix.de> <4ECCD910.1010004@freescale.com>
 <1322048442.1516.274.camel@vkoul-udesk3>
Message-ID: <4ECDAF22.6060308@freescale.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

? 2011?11?23? 19:40, Vinod Koul ??:
> On Wed, 2011-11-23 at 19:29 +0800, Huang Shijie wrote:
>>> On Wed, Nov 23, 2011 at 07:13:23PM +0800, Huang Shijie wrote:
>>>>>>>> +	/* save the real count we received or transmitted. */
>>>>>>>> +	chan->private = (void *)count;
>>>>>>> And if someone later needs another variable which is private?
>>>>>>>
>>>>>> I ever wanted to add an new parameter `void *` to dma_aync_tx_callback,
>>>>>> but it seemed i have
>>>>>> to change a lot of files.
>>>>>>
>>>>>> Do you have any better suggestion?
>>>>> Use a private struct and put count in there.
>>>>>
>>>> Where to put the private struct? in the imx-sdma.c ?
>>>> If i put it there, how can i get it in the UART driver with the current
>>>> DMA API?
>>> So, in the UART driver you assume that void* is an int? Or how do you
>>> currently use count?
>>>
>> In the UART driver, I use the following lines:
>> -------------------------------------------------------
>> + struct dma_chan *chan = sport->dma_chan_rx;
>> + unsigned int count = (unsigned int)chan->private;
>> -------------------------------------------------------
> Chan->private is a depreciated field, and will be removed soon...
> possibly 3.3, so obviosly any usage of it is incorrect
>
> Why dont you use .device_tx_status callback and return the number of
> bytes remaining to be transmitted in residue value of the struct
> dma_tx_state. That should be size - count.
>
Thanks a lot.

Huang Shijie