linux-kernel - [PATCH 2/2] i3c: master: svc: fix invalidate IBI type and miss call client IBI handler

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Date: Wed, 24 Apr 2024 15:00:30 -0400
From: Frank Li <Frank.Li@....com>
To: Miquel Raynal <miquel.raynal@...tlin.com>,
	Conor Culhane <conor.culhane@...vaco.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	linux-i3c@...ts.infradead.org (moderated list:SILVACO I3C DUAL-ROLE MASTER),
	linux-kernel@...r.kernel.org (open list)
Cc: imx@...ts.linux.dev
Subject: [PATCH 2/2] i3c: master: svc: fix invalidate IBI type and miss call client IBI handler

In an In-Band Interrupt (IBI) handle, the code logic is as follows:

1: writel(SVC_I3C_MCTRL_REQUEST_AUTO_IBI | SVC_I3C_MCTRL_IBIRESP_AUTO,
	  master->regs + SVC_I3C_MCTRL);

2: ret = readl_relaxed_poll_timeout(master->regs + SVC_I3C_MSTATUS, val,
                                    SVC_I3C_MSTATUS_IBIWON(val), 0, 1000);
	...
3: ibitype = SVC_I3C_MSTATUS_IBITYPE(status);
   ibiaddr = SVC_I3C_MSTATUS_IBIADDR(status);

SVC_I3C_MSTATUS_IBIWON may be set before step 1. Thus, step 2 will return
immediately, and the I3C controller has not sent out the 9th SCL yet.
Consequently, ibitype and ibiaddr are 0, resulting in an unknown IBI type
occurrence and missing call I3C client driver's IBI handler.

A typical case is that SVC_I3C_MSTATUS_IBIWON is set when an IBI occurs
during the controller send start frame in svc_i3c_master_xfer().

Clear SVC_I3C_MSTATUS_IBIWON before issue SVC_I3C_MCTRL_REQUEST_AUTO_IBI
to fix this issue.

Cc: stable@...r.kernel.org
Fixes: 5e5e3c92e748 ("i3c: master: svc: fix wrong data return when IBI happen during start frame")
Signed-off-by: Frank Li <Frank.Li@....com>
---
 drivers/i3c/master/svc-i3c-master.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index a2298ab460a37..3bfe8e694f840 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -415,6 +415,9 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
 	int ret;
 
 	mutex_lock(&master->lock);
+	/* Clear the interrupt status */
+	writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
+
 	/* Acknowledge the incoming interrupt with the AUTOIBI mechanism */
 	writel(SVC_I3C_MCTRL_REQUEST_AUTO_IBI |
 	       SVC_I3C_MCTRL_IBIRESP_AUTO,
@@ -429,9 +432,6 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
 		goto reenable_ibis;
 	}
 
-	/* Clear the interrupt status */
-	writel(SVC_I3C_MINT_IBIWON, master->regs + SVC_I3C_MSTATUS);
-
 	status = readl(master->regs + SVC_I3C_MSTATUS);
 	ibitype = SVC_I3C_MSTATUS_IBITYPE(status);
 	ibiaddr = SVC_I3C_MSTATUS_IBIADDR(status);
-- 
2.34.1