mmc: host: sdhci-esdhc-imx: async sdio interrupt and hardware auto-tuning

[Marcel Ziswiler]

Hi there

When we investigated an SDIO Wi-Fi stability issue I discovered the
following downstream-only commit in NXP's latest downstream BSP
5.15.52_2.1.0 [1]. The asynchronous SDIO interrupt seems to adversly
affect the hardware auto-tuning. As a workaround what got implemented
is an fsl-custom device tree property that limits the auto-tuning to
1 bit only (e.g. on DAT[0]) while the SDIO interrupt stays on DAT[1].

Does anybody know any further details about this?

Would this be a reasonable thing to also implement upstream?

Unfortunately, so far we have not really done any extensive SDIO
validation using upstream but I plan to set something like that up so
we may see whether or not we are also hitting such issue.

Thanks!

[1] https://github.com/nxp-imx/linux-imx/commit/84c529a1474a9f6614e475e178ca5fe23b6177de

Cheers

Marcel