Re: [RFC PATCH 6/6] spi: spi-s3c64xx: Move DMA initialization

["Łukasz Czerwiński" <l.czerwinski@samsung.com>]

On 09/10/2013 06:32 PM, Mark Brown wrote:
> On Tue, Sep 10, 2013 at 03:16:59PM +0200, Łukasz Czerwiński wrote:
>> On 09/10/2013 02:03 PM, Mark Brown wrote:
>>> On Tue, Sep 10, 2013 at 01:24:01PM +0200, Łukasz Czerwiński wrote:
>
>>>> For 16kB buffer upload time is reduced from ~90ms to ~80ms (I tested
>>>> with S5C73M3 355560B transfer). If you think that performance
>>>> increase isn't valuable we should skip that patch.
>
>>> That does seem worthwhile.  Is that just a single transfer in isolation?
>
>> I gave you summary time when firmware is transferred via 22x16kB blocks.
>> Each transfer was isolated.
>
> OK, so that's the per-transfer number?  I'm just wondering if moving it
> to prepare/unprepare would achieve the same effect here.
>
Yes

You are right.

S5C73M3 splits firmware into several spi_messages with single SPI 
transfer.  It caused for each single spi_message transfer 
prepare/unprepare.  I tried mistakenly optimize through moving 
dma_channel_request(in prepare) from prepare to probe(do it once).

I based my patch on the spi-tegra114.c driver. 	There is 
dma_chanel_request at the beginning in the probe function.
I really should correct S5C73M3 firmware upload function.

When I added small modification into S5C73M3 driver I achieved the same 
effect.

Sorry for wasting your time.

Thanks
Lukasz