[PATCH v2] mci: imx-esdhc: implement reset quirks for i.MX6 DualLite/Solo

[Sascha Hauer]

On Wed, May 04, 2016 at 03:25:57PM +0200, Stefan Christ wrote:
> First of all the reset values of MMC interfaces are differently between
> Quad and DualLite/Solo SoM.
> 
>                 Register VEND_SPEC2(0xC8)
>     Quad:       0x0
>     DualLite:   0x00000006
>     default:    0x00000006    (from i.MX6 Reference Manual)
> 
> Furthermore the ROM Code of Quad and DualLite uses the MMC interfaces
> differently when it loads the bootloader from that device:
> 
>                 Register DLL_CTRL(0x60)  Bit 25 FBCLK_SEL (0x48)
>     Quad:       0x0                      0
>     DualLite:   0x01000021               1
> 
> Since the linux kernel and barebox driver doesn't reset all registers,
> the MMC interface is in an inconsistent state, which leads to boot
> failures for some eMMC devices on the i.MX6 DualLite SoM. The errors
> look like:
> 
>     mmcblk3: error -110 sending stop command, original cmd response 0x900, card status 0x400900
>     mmcblk3: error -84 transferring data, sector 24578, nr 2, cmd response 0x900, card status 0x0
>     mmcblk3: retrying using single block read
>     mmcblk3: error -84 transferring data, sector 24578, nr 2, cmd response 0x900, card status 0x0
>     blk_update_request: I/O error, dev mmcblk3, sector 24578
> 
> It's sufficient to reset register DLL_CTRL and bit FBCLK_SEL. Register
> VEND_SPEC2 has no effect.
> 
> Signed-off-by: Stefan Christ <s.christ at phytec.de>

Nice fix. Applied, thanks

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |