sdhci-omap: issues with PM features since 5.16

[Romain Naour <romain.naour@smile.fr>]

Hello,

I'm upgrading the kernel from 5.10.168 to 6.1.69 (both from TI tree) on a custom
board based on a AM574x SoC and I noticed a regression on the sdhci-omap driver.

The emmc was working on the 5.10 kernel using mmc-hs200 powered at 1,8v (mmc2).

The first sign of the issue is a cache flush error during the first boot:

mmc1: cache flush error -110 (ETIMEDOUT)
mmc1: error -110 doing aggressive suspend

followed by I/O errors produced by fdisk -l /dev/mmcblk1boot1:

I/O error, dev mmcblk1boot0, sector 64384 op 0x0:(READ) flags 0x80700 phys_seg 1
prio class 2
I/O error, dev mmcblk1boot1, sector 64384 op 0x0:(READ) flags 0x80700 phys_seg 1
prio class 2
I/O error, dev mmcblk1boot1, sector 64384 op 0x0:(READ) flags 0x0 phys_seg 1
prio class 2
Buffer I/O error on dev mmcblk1boot1, logical block 8048, async page read
I/O error, dev mmcblk1boot0, sector 64384 op 0x0:(READ) flags 0x0 phys_seg 1
prio class 2
Buffer I/O error on dev mmcblk1boot0, logical block 8048, async page read

Here is what I had as mmc infos on 5.10 kernel:

# cat /sys/kernel/debug/mmc0/ios
clock:		50000000 Hz
vdd:		21 (3.3 ~ 3.4 V)
bus mode:	2 (push-pull)
chip select:	0 (don't care)
power mode:	2 (on)
bus width:	2 (4 bits)
timing spec:	2 (sd high-speed)
signal voltage:	0 (3.30 V)
driver type:	0 (driver type B)

# cat /sys/kernel/debug/mmc1/ios
clock:		192000000 Hz
vdd:		7 (1.65 - 1.95 V)
bus mode:	2 (push-pull)
chip select:	0 (don't care)
power mode:	2 (on)
bus width:	3 (8 bits)
timing spec:	9 (mmc HS200)
signal voltage:	1 (1.80 V)
driver type:	0 (driver type B)

Now with 6.1:

# cat /sys/kernel/debug/mmc0/ios
clock:		0 Hz
vdd:		0 (invalid)
bus mode:	2 (push-pull)
chip select:	0 (don't care)
power mode:	0 (off)
bus width:	0 (1 bits)
timing spec:	0 (legacy)
signal voltage:	0 (3.30 V)
driver type:	0 (driver type B)


# cat /sys/kernel/debug/mmc1/ios
clock:		0 Hz
vdd:		0 (invalid)
bus mode:	2 (push-pull)
chip select:	0 (don't care)
power mode:	0 (off)
bus width:	0 (1 bits)
timing spec:	0 (legacy)
signal voltage:	1 (1.80 V)
driver type:	0 (driver type B)

I'm able to reproduce on the IDK574x evaluation board (where the emmc is powered
at 3v3) with vanilla kernels.

I had to revert all commits related to "PM runtime functions" [1] and "card
power off and enable aggressive PM" [2] from kernel 5.16 to use the emmc again
on both boards.

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f433e8aac6b94218394c6e7b80bb89e4e79c9549
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3edf588e7fe00e90d1dc7fb9e599861b2c2cf442

Best regards,
Romain