[U-Boot] DMA drivers in U-Boot?

[U-Boot] DMA drivers in U-Boot?

[Simon Schwarz]

Hi List,

I am working on integrating DMA into my SPL. As a matter of fact it is 
already working fine.

So, here are my questions:
- Is there an interest in having DMA drivers in U-Boot? (I only know of 
one in /drivers)
- Is there an API I should implement?
- Any other comments?

(ATM the transfer of the Linux-image is more than three times faster 
compared to the CPU copy)

Regards
Simon

[U-Boot] DMA drivers in U-Boot?

[Mike Frysinger]

On Wed, Sep 14, 2011 at 10:52, Simon Schwarz wrote:
> I am working on integrating DMA into my SPL. As a matter of fact it is
> already working fine.
>
> So, here are my questions:
> - Is there an interest in having DMA drivers in U-Boot? (I only know of
> one in /drivers)
> - Is there an API I should implement?
> - Any other comments?
>
> (ATM the transfer of the Linux-image is more than three times faster
> compared to the CPU copy)

Blackfin provides a dma_memcpy() helper.  what functionality do you
need the API to provide exactly ?  the Linux DMA API is quite large
and convoluted (many times with good reason), but i'd like to keep it
simple for us if possible.
-mike

[U-Boot] DMA drivers in U-Boot?

[Wolfgang Denk]

Dear Simon Schwarz,

In message <4E70BF94.1030306@gmail.com> you wrote:
> 
> I am working on integrating DMA into my SPL. As a matter of fact it is 
> already working fine.
> 
> So, here are my questions:
> - Is there an interest in having DMA drivers in U-Boot? (I only know of 
> one in /drivers)

It depends.  There are some devices which always use DMA, which cannot
operated in any other way.  Here the choice is simple :-)

In all other cases, the question is about effort (code size,
complexity) on one side, and win (reduction of boot time) on the other
side.

Eventually, two implementations might exist, and configuration
optioons to select one.

> (ATM the transfer of the Linux-image is more than three times faster 
> compared to the CPU copy)

Numbers like these are usually driving arguments :-)

Best regards,

Wolfgang Denk

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