linux-kernel - [PATCH v4 4/5] i3c: master: svc: Fix npcm845 invalid slvstart event

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Message-Id: <20250224083908.1880383-5-yschu@nuvoton.com>
Date: Mon, 24 Feb 2025 16:39:07 +0800
From: Stanley Chu <stanley.chuys@...il.com>
To: frank.li@....com,
	miquel.raynal@...tlin.com,
	alexandre.belloni@...tlin.com,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	linux-i3c@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	tomer.maimon@...oton.com,
	kwliu@...oton.com,
	yschu@...oton.com,
	Frank Li <Frank.Li@....com>
Subject: [PATCH v4 4/5] i3c: master: svc: Fix npcm845 invalid slvstart event

From: Stanley Chu <yschu@...oton.com>

I3C HW may generate an invalid SlvStart event when emitting a STOP.
If it is a true SlvStart, the MSTATUS state is SLVREQ. Check the
MSTATUS state to ignore the false event.

Reviewed-by: Frank Li <Frank.Li@....com>
Signed-off-by: Stanley Chu <yschu@...oton.com>
---
 drivers/i3c/master/svc-i3c-master.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 07506ae0f914..4eb4b8888725 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -59,6 +59,7 @@
 #define SVC_I3C_MSTATUS      0x088
 #define   SVC_I3C_MSTATUS_STATE(x) FIELD_GET(GENMASK(2, 0), (x))
 #define   SVC_I3C_MSTATUS_STATE_DAA(x) (SVC_I3C_MSTATUS_STATE(x) == 5)
+#define   SVC_I3C_MSTATUS_STATE_SLVREQ(x) (SVC_I3C_MSTATUS_STATE(x) == 1)
 #define   SVC_I3C_MSTATUS_STATE_IDLE(x) (SVC_I3C_MSTATUS_STATE(x) == 0)
 #define   SVC_I3C_MSTATUS_BETWEEN(x) FIELD_GET(BIT(4), (x))
 #define   SVC_I3C_MSTATUS_NACKED(x) FIELD_GET(BIT(5), (x))
@@ -618,6 +619,11 @@ 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;
+
 	svc_i3c_master_disable_interrupts(master);
 
 	/* Handle the interrupt in a non atomic context */
-- 
2.34.1