linux-kernel - [PATCH v4 6/6] i3c: master: svc: fix random hot join failure since timeout error

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Date:   Mon, 23 Oct 2023 12:16:58 -0400
From:   Frank Li <Frank.Li@....com>
To:     miquel.raynal@...tlin.com
Cc:     Frank.li@....com, alexandre.belloni@...tlin.com,
        conor.culhane@...vaco.com, imx@...ts.linux.dev, joe@...ches.com,
        linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 6/6] i3c: master: svc: fix random hot join failure since timeout error

master side report:
  silvaco-i3c-master 44330000.i3c-master: Error condition: MSTATUS 0x020090c7, MERRWARN 0x00100000

BIT 20: TIMEOUT error
  The module has stalled too long in a frame. This happens when:
  - The TX FIFO or RX FIFO is not handled and the bus is stuck in the
middle of a message,
  - No STOP was issued and between messages,
  - IBI manual is used and no decision was made.
  The maximum stall period is 100 μs.

This can be considered as being just a warning as the system IRQ latency
can easily be greater than 100us.

Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
Cc: stable@...r.kernel.org
Signed-off-by: Frank Li <Frank.Li@....com>
---

Notes:
    Change from v3 to v4
    - fixed missed update commit message
     Add dev_dbg for TIMEOUT case
     This can be considered as being just a warning as the system IRQ latency
    can easily be greater than 100us.
    
    Change from v2 to v3
    - remove 10k at commit message
    
    Change from v1 to v2
    -none
    
    Change from v1 to v2
    -none
    
    Change from v2 to v3
    - remove 10k at commit message
    
    Change from v1 to v2
    -none
    
    Change from v1 to v2
    -none

 drivers/i3c/master/svc-i3c-master.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 1a57fdebaa26d..6b6bdd163af4f 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -93,6 +93,7 @@
 #define SVC_I3C_MINTMASKED   0x098
 #define SVC_I3C_MERRWARN     0x09C
 #define   SVC_I3C_MERRWARN_NACK BIT(2)
+#define   SVC_I3C_MERRWARN_TIMEOUT BIT(20)
 #define SVC_I3C_MDMACTRL     0x0A0
 #define SVC_I3C_MDATACTRL    0x0AC
 #define   SVC_I3C_MDATACTRL_FLUSHTB BIT(0)
@@ -226,6 +227,14 @@ static bool svc_i3c_master_error(struct svc_i3c_master *master)
 	if (SVC_I3C_MSTATUS_ERRWARN(mstatus)) {
 		merrwarn = readl(master->regs + SVC_I3C_MERRWARN);
 		writel(merrwarn, master->regs + SVC_I3C_MERRWARN);
+
+		/* Ignore timeout error */
+		if (merrwarn & SVC_I3C_MERRWARN_TIMEOUT) {
+			dev_dbg(master->dev, "Warning condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n",
+				mstatus, merrwarn);
+			return false;
+		}
+
 		dev_err(master->dev,
 			"Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n",
 			mstatus, merrwarn);
-- 
2.34.1