Zephyr SD Card Remount Issue: fs_unmount vs. Disk Deinitialization Leading to EIO or Blocked Workqueue

Question

Zephyr RTOS SD Card Hot-Plug Re-Mount Issue

I'm implementing SD card hot-plug functionality in a Zephyr RTOS application. My workflow for managing the SD card involves the following Zephyr APIs:

Initialization/Insertion:

disk_access_ioctl(DISK_DRIVE_NAME, DISK_IOCTL_CTRL_INIT, NULL)
fs_mount(&mp)

Removal:

fs_unmount(&mp)

Problem Description:

When an SD card is inserted for the first time or on power-up, the sequence of disk_access_ioctl(DISK_IOCTL_CTRL_INIT) followed by fs_mount() works perfectly.

However, if I remove the SD card (triggering fs_unmount()) and then re-insert it, the re-initialization (disk_access_ioctl(DISK_IOCTL_CTRL_INIT)) succeeds, but the subsequent fs_mount() call fails consistently with an EIO (-5) error. The relevant log output is:

<err> sd: Failed to read from SDMMC -5
<err> sd: Card read failed
<err> fs: fs mount error (-5)

My understanding, based on the Zephyr documentation (e.g., the general usage of fs_unmount and the disk_access API), is that fs_unmount() should sufficiently deinitialize or prepare the disk for a future re-mount. It says I should have to explicitly use DISK_IOCTL_CTRL_DEINIT after fs_unmount.

Additional Observation (if I were to hypothetically force deinitialization):

If I manually deinit using disk_access_ioctl, within a k_work item scheduled on the system workqueue, it causes that k_work item to become permanently blocked or never complete its execution after the first removal. I also tried passing a pointer to a bool set as true as the buf arg but that also causes more errors.

My questions are:

What is the correct Zephyr API sequence or state management required to reliably remount an SD card after it has been fs_unmount'ed and then re-inserted?
Why would disk_access_ioctl(DISK_IOCTL_CTRL_INIT) succeed on re-insertion, but fs_mount() subsequently fail with EIO? What internal states or resources might be improperly released or re-initialized?
Am I using disk_access_ioctlcommandsincorrectly?

Any insights into successfully managing SD card hot-plugging in Zephyr, specifically regarding reliable re-mounting after unmounting, would be greatly appreciated.

aanas.sayed · Accepted Answer

Hi Dejan, thanks again for the responding. I am using a p ush slots that has an insertion detection pin. However it doesnt seem its ever enough time for it to deinit before removal. 
 As a second point althought as you mentioned those functions are blocking, they never return. So when that happens the whole system stops forever. Now I have solved it using the following: 
 1. Did not use either of the following:

disk_access_ioctl ( "SD" , DISK_IOCTL_CTRL_INIT , NULL ) ; 
 disk_access_ioctl ( "SD" , DISK_IOCTL_CTRL_DEINIT , NULL ) ; Earlier I would init the disk, mount, (do stuff) and then on pin triggered removal unmount and deinit. It seems I need to remove the init/deinit them altogether or deinit right after init if I need to access any parameters using the disk_access_ioctl command. 
 2. Even with the above solution for some reason everything would get blocked after at unmount. This was resolved once I moved to a lower priority workqueue. I was using the system workqueue before and it would block forever. 
 Thanks, 
 Aanas