linux-kernel - [PATCH v4 3/6] i3c: master: svc: fix ibi may not return mandatory data byte

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Date:   Mon, 23 Oct 2023 12:16:55 -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 3/6] i3c: master: svc: fix ibi may not return mandatory data byte

MSTATUS[RXPEND] is only updated after the data transfer cycle started. This
creates an issue when the I3C clock is slow, and the CPU is running fast
enough that MSTATUS[RXPEND] may not be updated when the code reaches
checking point. As a result, mandatory data can be missed.

Add a wait for MSTATUS[COMPLETE] to ensure that all mandatory data is
already in FIFO. It also works without mandatory data.

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

Notes:
    Change from v3 to v4
    - add review tag Miquel
    
    Change from v2 to v3
    - update commit message and add no mandatory data in commits message
    
    Change from v1 to v2
    - update commit message
      it also works without mandatory bytes
    
    Change from v1 to v2
    - update commit message
      it also works without mandatory bytes
    
    Change from v2 to v3
    - update commit message and add no mandatory data in commits message
    
    Change from v1 to v2
    - update commit message
      it also works without mandatory bytes
    
    Change from v1 to v2
    - update commit message
      it also works without mandatory bytes

 drivers/i3c/master/svc-i3c-master.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index abebef666b2bb..dd06b7c9333f1 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -332,6 +332,7 @@ static int svc_i3c_master_handle_ibi(struct svc_i3c_master *master,
 	struct i3c_ibi_slot *slot;
 	unsigned int count;
 	u32 mdatactrl;
+	int ret, val;
 	u8 *buf;
 
 	slot = i3c_generic_ibi_get_free_slot(data->ibi_pool);
@@ -341,6 +342,13 @@ static int svc_i3c_master_handle_ibi(struct svc_i3c_master *master,
 	slot->len = 0;
 	buf = slot->data;
 
+	ret = readl_relaxed_poll_timeout(master->regs + SVC_I3C_MSTATUS, val,
+						SVC_I3C_MSTATUS_COMPLETE(val), 0, 1000);
+	if (ret) {
+		dev_err(master->dev, "Timeout when polling for COMPLETE\n");
+		return ret;
+	}
+
 	while (SVC_I3C_MSTATUS_RXPEND(readl(master->regs + SVC_I3C_MSTATUS))  &&
 	       slot->len < SVC_I3C_FIFO_SIZE) {
 		mdatactrl = readl(master->regs + SVC_I3C_MDATACTRL);
-- 
2.34.1