[U-Boot] [PATCH 3/3] mmc: fsl: introduce wp_enable

[Peng Fan]

Hi Fabio,

On Tue, Jun 14, 2016 at 08:23:27PM -0300, Fabio Estevam wrote:
>Hi Peng,
>
>On Tue, Jun 14, 2016 at 8:01 PM, Fabio Estevam <festevam at gmail.com> wrote:
>
>> Just saw this issue on a mx6ul pico board: after adding I2C support
>> then the eMMC could not longer be written:
>>
>> => saveenv
>> Saving Environment to MMC...
>> Writing to MMC(0)...
>> The SD card is locked. Can not write to a locked card.
>>
>> mmc write failed
>> failed
>>
>> Your patch allows me to write to the eMMC succesfully:
>>
>> Tested-by: Fabio Estevam <fabio.estevam at nxp.com>

Thanks. This patch set was posted some time ago.

>
>Looks like this is an issue with the MX6UL IOMUXC, not the esdhc
>driver itself, so maybe we should not do this change for all other
>SoCs.
>
>If I manually do:
>=> mw.l 20E066C 2
>Then 'saveenv' works fine.
>
>Shouldn't we fix this in the MX6UL IOMUXC code instead?

No. We can not avoid such issue for now. You changed register 20e066c'value  to 2
2 means "CSI_DATA04_ALT8 — Selecting Pad: CSI_DATA04 for Mode: ALT8"

Look at "Figure 31-3. Daisy chain illustration" of i.MX6UL RM, if changed to 2,
that means you let CSI_DATA04 pad goes into usdhc1_wp.

select input can not be closed or disabled, which will cause issues like what
you met. Even worse, some one may need to redesign their board to avoid pin
conflict.

Regards,
Peng.