[PATCH] Revert "mmc: fsl_esdhc_imx: add wait_dat0() support"

[Marek Vasut]

On 1/28/22 08:30, Jaehoon Chung wrote:
> Hi Marek,

Hi,

> On 1/28/22 12:40, Marek Vasut wrote:
>> This reverts commit b5874b552ffa09bc1dc5dec6b5dd376c62dab45d.
>>
>> It seems the iMX8MM SDHC controller always reports DAT0 line status
>> as zero after voltage switch at the end of mmc_switch_voltage(), even
>> if it is supposed to be high and scope confirms the DAT0 is high.
>> Reverting this patch makes SDR104 work on iMX8MM, however, it is
>> not clear why the DAT0 status is not correctly reported by the
>> controller.
> 
> I didn't have an imx8mm board, so I wonder that other boards which is using fsl_esdhci_imx driver have same problem.

I have multiple 8mm, just not the 8mm-evk.

> I'm not sure...I remember that some controller doesn't support a busy signal.
> In kernel driver, also doesn't report correct status?

Kernel doesn't use this DAT0 readback, that's why it works in kernel.

U-Boot has been augmented with this DAT0 readback some time ago, I just 
noticed it on an 8mm board recently that it doesn't really work. There 
is also no errata.

I think it would be good to have NXP check this.