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

[Peter Meerwald <pmeerw@pmeerw.net>]

On Wed, 18 Jul 2012, Javier Martinez Canillas wrote:

> On Wed, Jul 18, 2012 at 10:36 AM, Shilimkar, Santosh
> <santosh.shilimkar@ti.com> wrote:
> > On Wed, Jul 18, 2012 at 1:14 PM, S, Venkatraman <svenkatr@ti.com> wrote:
> >> On Wed, Jul 18, 2012 at 12:40 PM, Tony Lindgren <tony@atomide.com> wrote:
> >>> * Shilimkar, Santosh <santosh.shilimkar@ti.com> [120718 00:09]:
> >>>> On Wed, Jul 18, 2012 at 12:29 PM, Tony Lindgren <tony@atomide.com> wrote:
> >>>> > * Javier Martinez Canillas <javier@dowhile0.org> [120716 23:56]:
> >>>> >> On Tue, Jul 17, 2012 at 8:45 AM, Shilimkar, Santosh
> >>>> >> <santosh.shilimkar@ti.com> wrote:
> >>>> >> > Hi,
> >>>> >> >
> >>>> >> > On Tue, Jul 17, 2012 at 6:00 AM, Javier Martinez Canillas
> >>>> >> > <javier@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@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.
> >
> > Same case for SPI driver as well. It uses DMA for everything except the cases
> > where DMA doesn't make sense like 1 byte/2 byte etc. And its not configurable,
> >
> > At least considering this, it is better we do this per driver than enabling
> > it at SOC config.
> >
> > Regards
> > Santosh
> > --
> 
> Hi Santosh,
> 
> And what about enabling it at the SoC config level but making the
> drivers dependant on CONFIG_DMADEVICES and CONFIG_DMA_OMAP? If you
> agree I can send something like this in two different patches (one for
> the omap2plus_defconfig and another to make the drivers dependant on
> the config option):
> 
> diff --git a/arch/arm/configs/omap2plus_defconfig
> b/arch/arm/configs/omap2plus_defconfig
> index b152de7..e58edc3 100644
> --- a/arch/arm/configs/omap2plus_defconfig
> +++ b/arch/arm/configs/omap2plus_defconfig
> @@ -193,6 +193,8 @@ CONFIG_MMC_OMAP_HS=y
>  CONFIG_RTC_CLASS=y
>  CONFIG_RTC_DRV_TWL92330=y
>  CONFIG_RTC_DRV_TWL4030=y
> +CONFIG_DMADEVICES=y
> +CONFIG_DMA_OMAP=y
>  CONFIG_EXT2_FS=y
>  CONFIG_EXT3_FS=y
>  # CONFIG_EXT3_FS_XATTR is not set

above has been merged, 89269ef1f0abc72c551198123e19cd4edfd43cf4
but I am missing the patches below in mainline (3.6-rc3) -- what happened?

as Javier pointed out in https://patchwork.kernel.org/patch/1203391/, 
MMC is broken support e.g. on beagleboard unless DMA_OMAP is defined

I suggest to take below patches and help to avoid some extra gray hair for 
people looking for a fix for non-booting beagleboards

thanks, p.

> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index aa131b3..314c7bd 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -231,7 +231,7 @@ config MMC_SDHCI_S3C_DMA
> 
>  config MMC_OMAP
>  	tristate "TI OMAP Multimedia Card Interface support"
> -	depends on ARCH_OMAP
> +	depends on ARCH_OMAP && DMADEVICES && DMA_OMAP
>  	select TPS65010 if MACH_OMAP_H2
>  	help
>  	  This selects the TI OMAP Multimedia card Interface.
> @@ -242,7 +242,8 @@ config MMC_OMAP
> 
>  config MMC_OMAP_HS
>  	tristate "TI OMAP High Speed Multimedia Card Interface support"
> -	depends on SOC_OMAP2430 || ARCH_OMAP3 || ARCH_OMAP4
> +	depends on (SOC_OMAP2430 || ARCH_OMAP3 || ARCH_OMAP4) && \
> +		    DMADEVICES && DMA_OMAP
>  	help
>  	  This selects the TI OMAP High Speed Multimedia card Interface.
>  	  If you have an OMAP2430 or OMAP3 board or OMAP4 board with a
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index cd2fe35..1c23242 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -237,7 +237,7 @@ config SPI_OMAP_UWIRE
> 
>  config SPI_OMAP24XX
>  	tristate "McSPI driver for OMAP"
> -	depends on ARCH_OMAP2PLUS
> +	depends on ARCH_OMAP2PLUS && DMADEVICES && DMA_OMAP
>  	help
>  	  SPI master controller for OMAP24XX and later Multichannel SPI
>  	  (McSPI) modules.


-- 

Peter Meerwald
+43-664-2444418 (mobile)