Re: [PATCH V4 1/3] mmc: sdhci: add support for using external DMA devices

From: Faiz Abbas
Date: Wed Jan 02 2019 - 03:23:47 EST


On 27/12/18 1:32 PM, Chunyan Zhang wrote:
> On Thu, 27 Dec 2018 at 15:44, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>> On 11/12/18 11:12 AM, Chunyan Zhang wrote:
>>> Some standard SD host controllers can support both external dma
>>> controllers as well as ADMA/SDMA in which the SD host controller
>>> acts as DMA master. TI's omap controller is the case as an example.
>>> Currently the generic SDHCI code supports ADMA/SDMA integrated in
>>> the host controller but does not have any support for external DMA
>>> controllers implemented using dmaengine, meaning that custom code is
>>> needed for any systems that use an external DMA controller with SDHCI.
>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
>> FYI, I am waiting on successful testing before reviewing these patches again.
> Yeah, that makes sense, thanks Adrian!
> I intend to send out another new patchset after the holidays.
> After had another look at omap_hsmmc, I knew something need to be
> modified (emailed Faiz about this privately), but I was still not sure
> if it can fix the problem Faiz found.

I am currently working on moving am335 and am43 devices from omap_hsmmc
to sdhci-omap driver. External DMA would be an integral part of this.
The plan is to post these patches as a part of my series after testing
on all those devices.