Re: [RFC][media] s5p-fimc : Need to modifiy input DMA burst count for FIMC performance.

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Hi Hyunwoong,

On 12/08/2010 08:12 AM, Hyunwoong Kim wrote:
> Hello,
> 
> I am writing this mail to suggest one thing regarding FIMC H/W setting.
> You wrote the below code for setting S5P_MSCTRL_FRAME_COUNT as one.
> 
> cfg |= (S5P_MSCTRL_FRAME_COUNT(1) | S5P_MSCTRL_INPUT_MEMORY);
> 
> I think itâs better way to set the value of S5P_MSCTRL_FRAME_COUNT as 4.
> Because, this value means input DMA burst count.
> The default value of input DMA burst count in FIMC is 4.
> And I guess if the value of less than 4 is set as input DMA burst count, 
> the performance of input DMA in FIMC will be lower.
> 
> I want to know how about your opinions.

I did a test with the input DMA burst value of 1 and 4 and didn't observe
an improvement in the image processing time. I guess it could show up when
the system bus is heavily loaded or with HD input image size or bigger.

The datasheet is not too verbose about this parameter, I am also not sure if
it has any impact on the input pixel size alignment.
I'm considering making a patch changing input DMA burst count to the default
value and I've also noticed that S5P_MSCTRL_FRAME_COUNT_MASK is 3 instead of 0xF.
Thank you for review.


Regards,
-- 
Sylwester Nawrocki
Samsung Poland R&D Center
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