[PATCH v1 0/2] i3c: master: svc: Fix false SLVSTART issues on NPCM845

[Stanley Chu]

From: Stanley Chu <yschu at nuvoton.com>

The Nuvoton NPCM845 I3C controller has a hardware quirk
(SVC_I3C_QUIRK_FALSE_SLVSTART) where a spurious SLVSTART interrupt
may be generated. This series addresses two separate issues related to
this quirk:

1. A race condition where a real IBI arrives after MSTATUS is latched
   but before the SLVSTART status is cleared, causing the IRQ handler
   to return early on a stale snapshot and miss the pending IBI. Fixed
   by re-reading MSTATUS after clearing the interrupt status.

2. When a target holds SDA low, the controller reports a Master Request
   (MR). Emitting the required STOP condition in response spuriously
   sets SLVSTART again, re-entering the MR handler in a loop and causing
   an IRQ storm. Fixed by explicitly clearing SLVSTART after the STOP
   in the MR handler.

Stanley Chu (2):
  i3c: master: svc: Fix missed IBI after false SLVSTART on NPCM845
  i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845

 drivers/i3c/master/svc-i3c-master.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

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2.34.1