[PATCH 1/1] mmc: host: enable OMAP DMA engine support for omap hosts by default

[S, Venkatraman]

On Wed, Jul 18, 2012 at 12:40 PM, Tony Lindgren <tony at atomide.com> wrote:
> * Shilimkar, Santosh <santosh.shilimkar at ti.com> [120718 00:09]:
>> On Wed, Jul 18, 2012 at 12:29 PM, Tony Lindgren <tony at atomide.com> wrote:
>> > * Javier Martinez Canillas <javier at dowhile0.org> [120716 23:56]:
>> >> On Tue, Jul 17, 2012 at 8:45 AM, Shilimkar, Santosh
>> >> <santosh.shilimkar at ti.com> wrote:
>> >> > Hi,
>> >> >
>> >> > On Tue, Jul 17, 2012 at 6:00 AM, Javier Martinez Canillas
>> >> > <javier at dowhile0.org> wrote:
>> >> >> The OMAP MMC and OMAP High Speed MMC hosts now use entirely the DMA
>> >> >> engine API instead of the previous private DMA API implementation.
>> >> >>
>> >> >> So, if the kernel is built with support for any of these hosts but it
>> >> >> doesn't support DMA devices nor OMAP DMA support, it fails when trying
>> >> >> to obtain a DMA channel which leads to the following error on an OMAP3
>> >> >> IGEPv2 Rev.C board (and probably on most OMAP boards with MMC support):
>> >> >>
>> >> >> [    2.199981] omap_hsmmc omap_hsmmc.1: unable to obtain RX DMA engine channel 48
>> >> >> [    2.215087] omap_hsmmc omap_hsmmc.0: unable to obtain RX DMA engine channel 62
>> >> >>
>> >> >> selecting automatically CONFIG_DMADEVICES and CONFIG_DMA_OMAP solves it.
>> >> >>
>> >> >> Signed-off-by: Javier Martinez Canillas <javier at dowhile0.org>
>> >> >> ---
>> >> > Considering, we are updating drivers to select the DMA engine, can you
>> >> > also include
>> >> > "drivers/spi/spi-omap2-mcspi.c" which is also updated for DMA engine.
>> >> >
>> >> > Regards
>> >> > Santosh
>> >>
>> >> Hi Santosh,
>> >>
>> >> Ok, I'll send a v2 now which includes spi-omap2-mcspi then.
>> >
>> > I don't think we should do this, the drivers should work with and without
>> > dma. This just needs to be added to the omap2plus_defconfig.
>> >
>> Well this was not decided based on any DMA CONFIG option before for
>> the subject drivers. It is already by default enabled if the DMA is supported
>> by the driver IP. There is a possibility to disable it from driver platform/dt
>> data so that still remains.
>
> I think it should rather be that if the driver is broken and does not work
> without DMA, it should have depends on CONFIG_DMA_OMAP.
>
I can confirm that omap MMC can't work without DMA; polled mode is not
supported / implemented.