Re: [PATCH/RFC v2 1/5] mmc: sh_mobile_sdhi, tmio: make dma more modular

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Hi Simon,

On Thu, Jun 30, 2016 at 12:05 AM, Simon Horman
<horms+renesas@xxxxxxxxxxxx> wrote:
> Refactor DMA support to allow it to be provided by a set of call-backs
> that are provided by a host driver. The motivation is to allow multiple
> DMA implementations to be provided and instantiated at run-time.
>
> Instantiate the existing DMA implementation from the sh_mobile_sdhi driver
> which appears to match the current use-case. This has the side effect
> of moving the DMA code from the tmio_core to the sh_mobile_sdhi driver.
>
> A follow-up patch will change the source file for the SDHI DMA
> implementation accordingly.
>
> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> v2
> * Fix compilation issue due to error in Makefile
> * Use MMC_SDHI_SYSC_DMA rather than MMC_SDHI_DMA as new Kconfig symbole
>   to better reflect revamped file rename in a follow-up patch.
>
> Todo: Investigate removing ifdef
> ---
>  drivers/mmc/host/Kconfig          |  9 ++++++++
>  drivers/mmc/host/Makefile         |  4 +++-
>  drivers/mmc/host/sh_mobile_sdhi.c | 13 +++++++++++
>  drivers/mmc/host/tmio_mmc.h       | 39 ++++++++------------------------
>  drivers/mmc/host/tmio_mmc_dma.c   | 26 +++++++++++++++++-----
>  drivers/mmc/host/tmio_mmc_pio.c   | 47 +++++++++++++++++++++++++++++++++++++++
>  6 files changed, 102 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index 5274f503a39a..a0b6c1773e33 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -554,10 +554,19 @@ config MMC_SDHI
>         depends on SUPERH || ARM || ARM64
>         depends on SUPERH || ARCH_RENESAS || COMPILE_TEST
>         select MMC_TMIO_CORE
> +       select MMC_SDHI_SYSC_DMA if (SUPERH || ARM)

MMC_SDHI_SYS_DMAC?

>         help
>           This provides support for the SDHI SD/SDIO controller found in
>           SuperH and ARM SH-Mobile SoCs
>
> +config MMC_SDHI_SYSC_DMA

MMC_SDHI_SYS_DMAC??

> +       tristate "DMA support use of SYSC DMAC with SDHI SD/SDIO controller"

SYS DMAC

(SYSC is the System Controller for Power Areas)

> +       depends on SUPERH || ARM || COMPILE_TEST
> +       depends on MMC_SDHI
> +       help
> +         This provides DMA support for the SDHI SD/SDIO controller
> +         found in SuperH and Renesas ARM based SoCs.
> +
>  config MMC_CB710
>         tristate "ENE CB710 MMC/SD Interface support"
>         depends on PCI
> diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
> index e2bdaaf43184..4ed6f250213a 100644
> --- a/drivers/mmc/host/Makefile
> +++ b/drivers/mmc/host/Makefile
> @@ -37,8 +37,10 @@ obj-$(CONFIG_MMC_SDRICOH_CS) += sdricoh_cs.o
>  obj-$(CONFIG_MMC_TMIO)         += tmio_mmc.o
>  obj-$(CONFIG_MMC_TMIO_CORE)    += tmio_mmc_core.o
>  tmio_mmc_core-y                        := tmio_mmc_pio.o
> -tmio_mmc_core-$(subst m,y,$(CONFIG_MMC_SDHI))  += tmio_mmc_dma.o
>  obj-$(CONFIG_MMC_SDHI)         += sh_mobile_sdhi.o
> +ifeq ($(subst m,y,$(CONFIG_MMC_SDHI_SYSC_DMA)),y)
> +obj-$(CONFIG_MMC_SDHI)         += tmio_mmc_dma.o
> +endif
>  obj-$(CONFIG_MMC_CB710)                += cb710-mmc.o
>  obj-$(CONFIG_MMC_VIA_SDMMC)    += via-sdmmc.o
>  obj-$(CONFIG_SDH_BFIN)         += bfin_sdh.o
> diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c
> index c3b651bf89cb..45543ed37e5f 100644
> --- a/drivers/mmc/host/sh_mobile_sdhi.c
> +++ b/drivers/mmc/host/sh_mobile_sdhi.c
> @@ -106,6 +106,15 @@ struct sh_mobile_sdhi {
>         struct pinctrl_state *pins_default, *pins_uhs;
>  };
>
> +#if IS_ENABLED(MMC_SDHI_SYSC_DMA)

This should be "#if IS_ENABLED(CONFIG_MMC_SDHI_SYSC_DMA)",
else probing fails on all platforms where SDHI uses the SYS DMAC:

    sh_mobile_sdhi: probe of ee100000.sd failed with error -22

> +int tmio_mmc_init_dma(void);
> +#else
> +static int tmio_mmc_init_dma(void)
> +{
> +       return -EINVAL;

Still, I don't know if this is the right approach: if CONFIG_MMC_SDHI_SYSC_DMA
is ever disabled, the driver will just fail during probing, instead of falling
back to PIO.

> +}
> +#endif
> +

And there's another issue:

    WARNING: modpost: Found 1 section mismatch(es).
    To see full details build your kernel with:
    'make CONFIG_DEBUG_SECTION_MISMATCH=y'

Doing that doesn't help much, though:

    WARNING: drivers/built-in.o(.text+0x190f7c): Section mismatch in
reference from
    the function tmio_mmc_init_dma() to the (unknown reference)
    .init.data:(unknown)
    The function tmio_mmc_init_dma() references
    the (unknown reference) __initdata (unknown).
    This is often because tmio_mmc_init_dma lacks a __initdata
    annotation or the annotation of (unknown) is wrong.

The warning goes away later in the series, though.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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