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From: Joshua Yeong <joshua.yeong@starfivetech.com>
To: <alexandre.belloni@bootlin.com>, <miquel.raynal@bootlin.com>
Cc: <linux-i3c@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
	"Joshua Yeong" <joshua.yeong@starfivetech.com>
Subject: [PATCH v3 1/1] i3c: Add fallback method for GETMXDS CCC
Date: Tue, 14 Nov 2023 16:55:25 +0800	[thread overview]
Message-ID: <20231114085525.6271-2-joshua.yeong@starfivetech.com> (raw)
In-Reply-To: <20231114085525.6271-1-joshua.yeong@starfivetech.com>

Some I3C hardware will report error when an incorrect length is received from
device. GETMXDS CCC are available in 2 formats: without turnaround time (format
1) and with turnaround time (format 2). There is no mechanics to determine which
format is supported by device. So in case sending GETMXDS CCC format 2 resulted
in a failure, try sending GETMXDS CCC format 1 instead.

Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com>
---
 drivers/i3c/master.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 95caa162706f..718b643cb54d 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1130,8 +1130,16 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
 
 	i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
 	ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
-	if (ret)
-		goto out;
+	if (ret) {
+		/*
+		 * Retry when the device does not support max read turnaround
+		 * while expecting shorter length from this CCC command.
+		 */
+		dest->payload.len -= 3;
+		ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
+		if (ret)
+			goto out;
+	}
 
 	if (dest.payload.len != 2 && dest.payload.len != 5) {
 		ret = -EIO;
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Joshua Yeong <joshua.yeong@starfivetech.com>
To: <alexandre.belloni@bootlin.com>, <miquel.raynal@bootlin.com>
Cc: <linux-i3c@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
	"Joshua Yeong" <joshua.yeong@starfivetech.com>
Subject: [PATCH v3 1/1] i3c: Add fallback method for GETMXDS CCC
Date: Tue, 14 Nov 2023 16:55:25 +0800	[thread overview]
Message-ID: <20231114085525.6271-2-joshua.yeong@starfivetech.com> (raw)
In-Reply-To: <20231114085525.6271-1-joshua.yeong@starfivetech.com>

Some I3C hardware will report error when an incorrect length is received from
device. GETMXDS CCC are available in 2 formats: without turnaround time (format
1) and with turnaround time (format 2). There is no mechanics to determine which
format is supported by device. So in case sending GETMXDS CCC format 2 resulted
in a failure, try sending GETMXDS CCC format 1 instead.

Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com>
---
 drivers/i3c/master.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 95caa162706f..718b643cb54d 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1130,8 +1130,16 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
 
 	i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
 	ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
-	if (ret)
-		goto out;
+	if (ret) {
+		/*
+		 * Retry when the device does not support max read turnaround
+		 * while expecting shorter length from this CCC command.
+		 */
+		dest->payload.len -= 3;
+		ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
+		if (ret)
+			goto out;
+	}
 
 	if (dest.payload.len != 2 && dest.payload.len != 5) {
 		ret = -EIO;
-- 
2.25.1


-- 
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c

  reply	other threads:[~2023-11-14  8:56 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-14  8:55 [PATCH v3 0/1] Fallback mechanism for GETMXDS CCC Joshua Yeong
2023-11-14  8:55 ` Joshua Yeong
2023-11-14  8:55 ` Joshua Yeong [this message]
2023-11-14  8:55   ` [PATCH v3 1/1] i3c: Add fallback method " Joshua Yeong
2023-11-14  8:57   ` Miquel Raynal
2023-11-14  8:57     ` Miquel Raynal
2023-11-16 22:40 ` [PATCH v3 0/1] Fallback mechanism " Alexandre Belloni
2023-11-16 22:40   ` Alexandre Belloni

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