[U-Boot] [PATCH 1/3] spl: imx6: Let spl_boot_device return USDHC1 or USDHC2

[Adam Ford]

On Wed, Aug 7, 2019 at 6:44 PM Ricardo Salveti <rsalveti at rsalveti.net> wrote:
>
> Hi Adam,
>
> On Thu, May 23, 2019 at 4:11 PM Adam Ford <aford173 at gmail.com> wrote:
> >
> > Currently, when the spl_boot_device checks the boot device, it
> > will only return MMC1 when it's either sd or eMMC regardless
> > of whether or not it's MMC1 or MMC2.  This is a problem when
> > booting from MMC2 if MMC isn't being manually configured like in
> > the DM_SPL case with SPL_OF_CONTROL.
> >
> > This patch will check the register and return either MMC1 or MMC2.
> >
> > Signed-off-by: Adam Ford <aford173 at gmail.com>
> >
> > diff --git a/arch/arm/mach-imx/spl.c b/arch/arm/mach-imx/spl.c
> > index 9f1e0f6a72..1f230aca33 100644
> > --- a/arch/arm/mach-imx/spl.c
> > +++ b/arch/arm/mach-imx/spl.c
> > @@ -24,6 +24,7 @@ u32 spl_boot_device(void)
> >  {
> >         unsigned int bmode = readl(&src_base->sbmr2);
> >         u32 reg = imx6_src_get_boot_mode();
> > +       u32 mmc_index = ((reg >> 11) & 0x03);
> >
> >         /*
> >          * Check for BMODE if serial downloader is enabled
> > @@ -84,11 +85,12 @@ u32 spl_boot_device(void)
> >         /* SD/eSD: 8.5.3, Table 8-15  */
> >         case IMX6_BMODE_SD:
> >         case IMX6_BMODE_ESD:
> > -               return BOOT_DEVICE_MMC1;
> > -       /* MMC/eMMC: 8.5.3 */
> >         case IMX6_BMODE_MMC:
> >         case IMX6_BMODE_EMMC:
> > -               return BOOT_DEVICE_MMC1;
> > +               if (mmc_index == 1)
> > +                       return BOOT_DEVICE_MMC2;
> > +               else
> > +                       return BOOT_DEVICE_MMC1;
>
> I just got to test v2019.10-rc1, which includes this change, and I'm
> unable to boot SPL on my Hummingboard 2, which uses USDHC-2 for
> sdcard.

I wondered if it would break a board.  It's why I originally sent it
as an RFC.  In my mind, it seems like we've created a system that only
supports one MMC, then we created a work-around to correctly identify
the MMC because the original implementation didn't.  I will admit, my
patch only checks for MMC1 or MMC2, but I don't have hardware to test
MMC3.
>
> Looks like this change breaks devices that are not using device
> tree/dynamic mmc initialization, as the MMC index will not necessarily
> be correct.

How hard would it be to use the device tree/dynamic initialization for
your board?  It seems to be the trend, and at least in some cases,
they've made it required and boards that don't comply get removed.  It
seems like we're prolonging.  I'd be open for an #ifdef hook around
it, but I am not sure how that would fly with the maintainers.  My
goal is to remove as much board-specific code as possible and move it
to the shared code to reduce the overhead and code size. Checking for
SPL_OF_CONTROL && DM_MMC might be potential work-around to the
work-around.

>
> Looking at mx6cuboxi.c in particular, fsl_esdhc_initialize will only
> be called once as it already knows which MMC device to initialize
> based on the BOOT_CFG register, causing the device mmc devnum to be 1
> only. The issue shows up when booting SPL as find_mmc_device will look
> for a matching dev_num index, which gets automatically increased when
> fsl_esdhc_initialize gets called (and which is only called once in my
> case, for MMC2).
>
> This is not an issue with imx6q_logic as at
> 8f4691e31a18254d225524a4b018b8cbcddc70b1 you removed
> fsl_esdhc_initialize, but all the other boards using MMC2 and doing
> only one single call will have the same problem.
>
> Not sure if there is an easy fix here, but converting everything to
> dynamic mmc initialization will required quite a bit of effort.

A bunch of boards have already started migrating to SPL_OF_CONTROL and
DM_MMC.  The imx6q_logic board was just a matter of changing some
config options and fixing and/or creating a -u-boot.dtsi file to
enable the various drivers in SPL, then removing the legacy code.

Stefano, what would your preference be?

adam
>
> Thanks,
> --
> Ricardo Salveti de Araujo