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SubjectRe: [PATCH] m32r: add simple dma
Hi Andrew,

On Friday 21 October 2016 08:59 AM, Andrew Morton wrote:
> On Sat, 8 Oct 2016 23:23:18 +0530 Sudip Mukherjee <> wrote:
>> Some builds of m32r were failing as it tried to build few drivers which
>> needed dma but m32r is not having dma support. Objections were raised
>> when it was tried to make those drivers depend on HAS_DMA.
> Huh. What were these objections? That sounds like the appropriate
> fix. And I suggest that a summary of those objections be captured in
> this patch's changelog.

Sorry for the delay in reply. Got busy in dayjob and relocation.

I was asked to provide dma stubs instead of adding HAS_DMA in the Kconfig.

And an old thread-

It appeared to me that instead of adding dma stubs and returning error
values from them it will be better to add dma_noop to m32r. Looking at
the simplicity of dma_noop it seems that it should work.
What will you suggest? Do i send v2 after adding the "dma stub" comment
and the link to the thread in the commit message or should I opt for dma

>> So the next
>> best thing is to add dma support to m32r.
>> dma_noop is a very simple dma with 1:1 memory mapping.
>> Signed-off-by: Sudip Mukherjee <>
>> ---
>> Hi Andrew,
>> Just to let you know that this was not tested on any board. I think I
>> have told you earlier that inspite of all my efforts I could not find
>> any source of information to procure a board of m32r.
> It is a worry. We're saying "m32r linux now supports these drivers",
> only we don't know if that is true.

FYI, I tried to contact Renesas for m32r boards and this is the reply I
received (Dated- Jan 20, 2016):
Hi Sudip-san,
I’m afraid but I don’t know about m32r.
Also I searched our private web site, I could not find usuful
information about m32r…
Best regards,
Yoshihiro Shimoda


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