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Date:	Tue, 6 Oct 2015 17:21:13 +0800
From:	Shawn Lin <>
To:	Vinod Koul <>
Cc:, Heiko Stuebner <>,
	Jaroslav Kysela <>,
	Takashi Iwai <>, Mark Brown <>,
	Doug Anderson <>,
	Olof Johansson <>,
	Sonny Rao <>,
	Addy Ke <>,,,,,,
Subject: Re: [PATCH v5 06/10] dmaengine: add API for getting dma controller's

Hi Vinod,

On 2015/10/5 23:37, Vinod Koul wrote:
> On Mon, Sep 14, 2015 at 07:48:59AM +0800, Shawn Lin wrote:
>> Add dmaengine_get_quirks API for peripheral devices to query
>> quirks if they need it to make special workaround due to broken
>> dma controller design.
>> Signed-off-by: Shawn Lin <>
>> ---
>> Changes in v5: None
>> Changes in v4: None
>> Changes in v3: None
>> Changes in v2: None
>> Changes in v1: None
>>   include/linux/dmaengine.h | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index e2f5eb4..5174ca4 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -704,6 +704,7 @@ struct dma_device {
>>   	int (*device_config)(struct dma_chan *chan,
>>   			     struct dma_slave_config *config);
>> +	int (*device_get_quirks)(struct dma_chan *chan);
> And why do we want to expose this to users? THis doesnt seem right!

Basically I agree not to expose dma's quirk to slave controllers...But, 
the fact I mentioned on cover letter explain the reasons why I have to 
let slave controllers know that they are working with a broken dma. It's 
a dilemma that if we don't want that to be exposed(let slave 
controllers' driver get the info via a API), we have to add broken quirk 
for all of them ,here and there, which seems to be a disaster:(

I would appreciate it if you could give me some suggestions at your 
earliest convenience. :)

> A quirk may exists but should be handled inside the controller driver and do
> appropriate action. You don't tell users or expect them to handle these

Best Regards
Shawn Lin

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