Subject: [PATCH 1/3] dmaengine: add dma_get_slave_sg_limits()

From: [email-masked] (Joel Fernandes)
Date: Mon, 22 Jul 2013 16:45:51 -0500

On 07/18/2013 11:16 AM, Vinod Koul wrote:> On Thu, Jul 18, 2013 at
11:46:39AM -0500, Joel Fernandes wrote:
>> From: Matt Porter <[email-masked]>
>>
>> Add a dmaengine API to retrieve slave SG transfer limits.
>>
>> The API is optionally implemented by dmaengine drivers and when
>> unimplemented will return a NULL pointer. A client driver using
>> this API provides the required dma channel, address width, and
>> burst size of the transfer. dma_get_slave_sg_limits() returns an
>> SG limits structure with the maximum number and size of SG segments
>> that the given channel can handle.
> Hi Joel,
>
> I have already resurrected this and generalized the API to get the slave
> capablities.
> https://lkml.org/lkml/2013/7/15/147

Hi Vinod,

get_caps and get_sg_limits are 2 different things, looks like this was
already discussed earlier, and this patch series is a separate API that
adds support for SG limits.

Infact, you can already see here that he changed the name of the
function from caps to dma_get_slave_sg_limits:
http://linux.davincidsp.com/pipermail/davinci-linux-open-source/2013-March/026601.html

Considering this, what is the way forward? Can this patch series be
merged as it is a different API as discussed above?

Summarizing:
* get_caps API cannot be used for this same purpose, as get_caps is done
_before_ the DMA channel can be configured from what it looks like:
* get_sg_limits, on the other hand is supposed to already have the
parameters required for configuring the DMA channel before hand.

Are there any other changes to the get_sg_limits series you would like
before it can be applied? Any other suggestions?

Thanks,

-Joel