IMX8MM SD UHS support

[Adam Ford]

On Wed, Dec 30, 2020 at 11:50 AM Fabio Estevam <festevam at gmail.com> wrote:
>
> Hi Tim,
>
> On Wed, Dec 30, 2020 at 1:54 PM Tim Harvey <tharvey at gateworks.com> wrote:
>
> > Andrey,
> >
> > I did mention that I am using the imx8mm-evk. When I saw that my
> > custom board was having issues with sd_get_capabilities() I switched
> > to the imx8mm-evk and confirmed my findings there.
> >
> > I'm using master (ab865a8ee5c1) with imx8mm_evk_defconfig running on
> > an imx8mm-evk board configured via dip switches to boot from eMMC. I
> > have a SDR104 microSD which detects and operates as such in Linux and
> > this is what I see in U-Boot:
> >
> > U-Boot SPL 2021.01-rc4-00029-gab865a8 (Dec 30 2020 - 08:29:24 -0800)
> > Normal Boot
> > WDT:   Started with servicing (60s timeout)
> > Trying to boot from MMC2
> >
> >
> > U-Boot 2021.01-rc4-00029-gab865a8 (Dec 30 2020 - 08:29:24 -0800)
> >
> > CPU:   Freescale i.MX8MMQ rev1.0 at 1200 MHz
> > Reset cause: POR
> > Model: FSL i.MX8MM EVK board
> > DRAM:  2 GiB
> > WDT:   Started with servicing (60s timeout)
> > MMC:   FSL_SDHC: 1, FSL_SDHC: 2
> > Loading Environment from MMC... OK
> > In:    serial
> > Out:   serial
> > Err:   serial
> > Net:   eth0: ethernet at 30be0000
> > Hit any key to stop autoboot:  0
> > u-boot=> mmc dev 1
> > Run CMD11 1.8V switch
> > switch to partitions #0, OK
> > mmc1 is current device
> > u-boot=> mmc info
> > Device: FSL_SDHC
> > Manufacturer ID: 1b
> > OEM: 534d
> > Name: 00000
> > Bus Speed: 50000000
> > Mode: SD High Speed (50MHz)
> > Rd Block Len: 512
> > SD version 3.0
> > High Capacity: Yes
> > Capacity: 14.9 GiB
> > Bus Width: 4-bit
> > Erase Group Size: 512 Bytes
> >
> > You can see that the 1.8V switch succeeds and the card is recognized
> > as high-speed but does not show the SDR104 capability.
>
> Could you please test this patch from Adam?
> https://patchwork.ozlabs.org/project/uboot/patch/20201230173907.2891555-1-aford173@gmail.com/

My patch probably won't do much more than the one from Andrey.  From
what I could gather, the generic mmc driver uses those flags to enable
the host caps.  My enables the same host caps by checking the
structure so the device tree flags are not needed.

The UHS and HS200/HS400 config options need to be enabled in Kconfig
for them to make a difference.  Part of me wonders if they should be
implied-on if USHDC is set, but that's a different issue.

If Tim is not seeing the SDR104 negotiated from Andrey's patch, it
probably won't change with mine.

adam