[PATCH v3 0/2] Retry the full device init on fatal link loss

[Shawn Lin]

On an RK3572 board the UFS device is sometimes reported dead during the
initialization at boot: DEVICE_FATAL_ERROR | UIC_LINK_LOST is latched and
the following UIC query fails with -EIO, leaving the device unusable.

  [    2.784068][    C0] ufshcd-rockchip 2a2d0000.ufs: ufshcd_check_errors: saved_err 0x880 saved_uic_err 0x0
  [    2.784112][    C0] host_regs: 00000000: 0187011f 00000000 00000200 00000000
  [    2.784125][    C0] host_regs: 00000010: 00000000 000005e6 00000000 00000000
  [    2.784137][    C0] host_regs: 00000020: 00000000 00031ef5 00000000 00000000
  [    2.784148][    C0] host_regs: 00000030: 00000008 00000001 00000000 00000000
  [    2.784159][    C0] host_regs: 00000040: 00000000 00000000 00000000 00000000
  [    2.784170][    C0] host_regs: 00000050: 02dd3000 00000001 00000000 00000000
  [    2.784182][    C0] host_regs: 00000060: 00000000 00000000 00000000 00000000
  [    2.784193][    C0] host_regs: 00000070: 02dd4000 00000001 00000000 00000000
  [    2.784204][    C0] host_regs: 00000080: 00000000 00000000 00000000 00000000
  [    2.784215][    C0] host_regs: 00000090: 00000016 00000000 00000000 00000000
  [    2.784266][   T13] ufshcd-rockchip 2a2d0000.ufs: ufshcd_err_handler started; HBA state eh_fatal; powered 1; shutting down 0; saved_err = 2176; saved_uic_err = 0; force_reset = 0
  [    2.784334][  T168] ufshcd-rockchip 2a2d0000.ufs: ufshcd_query_flag: Sending flag query for idn 1 failed, err = 5

Recover by resetting the device and the controller and redoing the whole
initialization sequence, up to three times with a 100 ms settle delay in
between. Patch 1/2 moves the initialization sequence into a new function
so that it can be retried as a unit, and patch 2/2 adds the retry loop
around its call site in ufshcd_init().


Changes in v3:
- Stop the controller before draining the error handler and clearing
  the error state, so that no interrupt can re-latch errors or
  schedule the error handler during the cleanup(sashiko)
- Remove the hwmon device and reset the exception event masks
  between retries, since the device reset wipes their state on the
  device side; also remove the hwmon device on the init failure
  path(sashiko)
- Only restore the MCQ mode after the controller re-enable and let
  the next attempt configure the queues(sashiko)
- Take the address of the by-value host_lock for
  spin_lock_irqsave()(sashiko)

Changes in v2:
- Move the initialization sequence into a new function and retry by
  looping over its call site instead of adding more gotos to
  ufshcd_init()(Bart)
- Stop a pending error handler and clear the error state latched by the
  failed attempt, so that the retry starts from a clean state(sashiko)
- Reconfigure and re-enable MCQ after the controller re-enable, since
  the HCE toggle clears the MCQ mode setting(sashiko)

Shawn Lin (2):
  scsi: ufs: core: Move the device initialization sequence into a new
    function
  scsi: ufs: core: Retry the full device init on fatal link loss

 drivers/ufs/core/ufshcd.c | 124 ++++++++++++++++++++++++++++++--------
 1 file changed, 99 insertions(+), 25 deletions(-)

-- 
2.25.1