From fa1d4fa118f4229168e9ca88cea260c5e5a94652 Mon Sep 17 00:00:00 2001 From: Stanley Chu Date: Mon, 13 Apr 2026 08:50:39 +0800 Subject: [PATCH] i3c: master: svc: Fix missed IBI after false SLVSTART on NPCM845 The NPCM845 I3C controller may raise a false SLVSTART interrupt. The handler first latches MSTATUS and then clears SLVSTART. If a real IBI request arrives after the handler latches MSTATUS but before it clears the SLVSTART interrupt status, HW sets the SLVREQ state. However, the handler still relies on the stale MSTATUS snapshot, returns early, and misses the real IBI. No further interrupt is generated for this pending IBI. Re-read MSTATUS to obtain the latest state and avoid missing a real IBI due to this race condition. Fixes: 4dd12e944f07 ("i3c: master: svc: Fix npcm845 invalid slvstart event") Signed-off-by: Stanley Chu Reviewed-by: Frank Li Link: https://patch.msgid.link/20260413005040.1211107-2-yschu@nuvoton.com Signed-off-by: Alexandre Belloni --- drivers/i3c/master/svc-i3c-master.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c index e2d99a3ac07d..63063741fbd1 100644 --- a/drivers/i3c/master/svc-i3c-master.c +++ b/drivers/i3c/master/svc-i3c-master.c @@ -672,10 +672,18 @@ static irqreturn_t svc_i3c_master_irq_handler(int irq, void *dev_id) /* Clear the interrupt status */ writel(SVC_I3C_MINT_SLVSTART, master->regs + SVC_I3C_MSTATUS); - /* Ignore the false event */ - if (svc_has_quirk(master, SVC_I3C_QUIRK_FALSE_SLVSTART) && - !SVC_I3C_MSTATUS_STATE_SLVREQ(active)) - return IRQ_HANDLED; + if (svc_has_quirk(master, SVC_I3C_QUIRK_FALSE_SLVSTART)) { + /* + * Re-read MSTATUS to obtain the latest state and avoid + * missing an IBI that arrives after MSTATUS is latched + * but before SLVSTART is cleared. + */ + active = readl(master->regs + SVC_I3C_MSTATUS); + + /* Ignore the false event */ + if (!SVC_I3C_MSTATUS_STATE_SLVREQ(active)) + return IRQ_HANDLED; + } /* * The SDA line remains low until the request is processed.