mmc: rtsx: card stuck busy fixes for Realtek PCI SD card readers

This series fixes some SD card timeout errors that occur after suspend and resume ops on systems with Realtek PCI card readers. These issues occur on my 2 RTS525A card readers and my RTS5261 card reader.

As a stress test, I ran the amd-s2idle script from amd-debug-tools to automate s2idle cycles and I launched a visual novel, WITCH ON THE HOLY NIGHT, from the SD card. Visual novels are basically just slideshows, and waiting for 10 seconds without advancing the text is an easy way to trigger rtsx_pci_runtime_suspend/rtsx_pci_runtime_resume. I set amd-s2idle to test with a 10 second long s2idle length with 13 seconds between runs.

The main symptom that always shows up is "mmc0: Card stuck being busy!" followed by timeouts and filesystem errors. This can occur during both runtime resume and s2idle resume:

[  260.638214] mmc0: error -110 doing runtime resume
[  261.054214] mmc0: card d555 removed
[  261.054382] Aborting journal on device mmcblk0p1-8.
[  261.054386] JBD2: I/O error when updating journal superblock for mmcblk0p1-8.
[  261.067729] EXT4-fs (mmcblk0p1): shut down requested (2)

Patch 1 adds a power_off callback so rtsx_pcr can notify the sdmmc driver during suspend, allowing it to reset prev_power_state. This ensures sd_power_on properly reinitializes the card on resume. It reduces the failure rate of "mmc0: Card stuck being busy!" after resume from 20% down to 4%.

Patch 2 increases the post-power-on settling delay from 1ms to 5ms. The shorter delay seems insufficient for reliable reinitialization after the hardware has been powered off during suspend. Increasing this reduces the failure rate from 4% down to 0%, tested with over 300 s2idle cycles.

Matthew Schwartz (2):
mmc: rtsx: reset power state on suspend
mmc: rtsx_pci_sdmmc: increase power-on settling delay to 5ms

 drivers/misc/cardreader/rtsx_pcr.c |  9 +++++++++
 drivers/mmc/host/rtsx_pci_sdmmc.c  | 24 +++++++++++++++++++++++-
 include/linux/rtsx_common.h        |  1 +
 3 files changed, 33 insertions(+), 1 deletion(-)

2.52.0