On 29/03/2022 22:16, Linus Walleij wrote:
On Tue, Mar 29, 2022 at 7:33 PM Manivannan Sadhasivam <mani@xxxxxxxxxx> 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?
There are multiple instances of BAM (Bus access manager) on Qcom SoC,
some of these instances are dedicated for each peripheral instance.
In this particular case we have 4 instances of BAM each of which are
dedicated to 4 instances of SD Controllers.
BAM dmaengine is used across many Qualcomm peripheral drivers.
--srini
Yours,
Linus Walleij
