Re: [PATCH 1/3] dt-bindings: mmc: mmci: add a property to disable DMA LLI

Linus Walleij
2022-03-29T21:18:16Z

On Tue, Mar 29, 2022 at 7:33 PM Manivannan Sadhasivam <mani@kernel.org> wrote:
> [Yann]
> > As for Prabhakar's answer, the IDMA here is inside our IP, and not used in
> > any other IP. So I'm not sure it is really relevant to move that to another
> > dmaengine driver.
>
> Okay, I think this justification makes sense. I was worried of DMA IPs that get
> sandwiched into many peripherals like the one on Renesas platforms. It turned
> out that each subsystem has to add internal DMA support for it :/

That is a justified worry.

Qualcomm has "BAM DMA" (I think it is called?) which is added to each IP
that needs DMA. drivers/mmc/host/mmci_qcom_dml.c
It's for older Qualcomm platforms but I *think* it is actually not just used
for the MMCI, just noone ever got around to adding it to any other
peripheral? Srini do you know?

Yours,
Linus Walleij