IMX8MM SD UHS support

[Tim Harvey]

On Wed, Dec 30, 2020 at 10:22 AM Adam Ford <aford173 at gmail.com> wrote:
>
> 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.
>

Right, the issue is not the host caps.

If I enable the calls to mmc_dump_capabilities() I see:
u-boot=> mmc info
Device: FSL_SDHC
Manufacturer ID: 3
OEM: 5344
Name: SL16G
Bus Speed: 50000000
Mode: SD High Speed (50MHz)
card capabilities: widths [4, 1] modes [MMC legacy, SD High Speed
(50MHz), UHS SDR12 (25MHz), UHS SDR25 (50MHz)]
host capabilities: widths [4, 1] modes [MMC legacy, MMC High Speed
(26MHz), SD High Speed (50MHz), MMC High Speed (52MHz), UHS DDR50
(50MHz), UHS SDR104 (208MHz)]
Rd Block Len: 512
SD version 3.0
High Capacity: Yes
Capacity: 14.8 GiB
Bus Width: 4-bit
Erase Group Size: 512 Bytes

You can see above the host shows DDR50/SDR104 capability but the card
does not. Again, the issue is in sd_get_capabilities()

Adam / Fabio, what results do you see on your board(s)?

Tim