linux-kernel - Re: [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback

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Message-ID: <f11a2775-63b8-6933-ab15-20e3927f0db7@codeaurora.org>
Date:   Fri, 19 Aug 2016 13:21:34 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Vinod Koul <vinod.koul@...el.com>
Cc:     Russell King - ARM Linux <linux@...linux.org.uk>,
        linux-arm-msm@...r.kernel.org, timur@...eaurora.org,
        linux-kernel@...r.kernel.org,
        Christopher Covington <cov@...eaurora.org>,
        dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] dmaengine: qcom_hidma: release the descriptor before the
 callback

On 8/19/2016 1:02 PM, Vinod Koul wrote:
> On Fri, Aug 19, 2016 at 07:13:43AM -0400, okaya@...eaurora.org wrote:
>> On 2016-08-19 01:52, Vinod Koul wrote:
>>> On Thu, Aug 18, 2016 at 11:48:52PM -0400, Sinan Kaya wrote:
>>>> On 8/18/2016 11:42 PM, Vinod Koul wrote:
>>>>> On Thu, Aug 18, 2016 at 11:26:28PM -0400, Sinan Kaya wrote:
>>>>>> On 8/18/2016 10:48 PM, Vinod Koul wrote:
>>>>>>>> Keep a size limited list with error cookies and flush them in terminate all?
>>>>>>> I think so, terminate_all anyway cleans up the channel. Btw what is the
>>>>>>> behaviour on error? Do you terminate or somthing else?
>>>>>>>
>>>>>>
>>>>>> On error, I flush all outstanding transactions with an error code and I reset
>>>>>> the channel. After the reset, the DMA channel is functional again. The client
>>>>>> doesn't need to shutdown anything.
>>>>>
>>>>> You mean from the client context or driver?
>>>>>
>>>>
>>>> The client doesn't need to call device_free_chan_resources and
>>>> device_terminate_all
>>>> to be specific. Client can certainly call these if it needs to
>>>> but it is not
>>>> required to recover the channel.
>>>
>>> You didn't answer my question!
>>>
>>> On error you said you flush, so who does that?
>>
>> This is done by the driver in interrupt context when an error
>> interrupt is received. All transactions are posted and hw is reset.
> 
> Hmmm, waht about the txn which are pending? DO you clear them..?
> 

Yes, I clear both pending and active transactions. 

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.