linux-kernel - [PATCH 4/6] i2c: spacemit: check SDA instead of SCL after bus reset

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Message-Id: <20250827-k1-i2c-atomic-v1-4-e59bea02d680@linux.spacemit.com>
Date: Wed, 27 Aug 2025 15:39:11 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Andi Shyti <andi.shyti@...nel.org>, Yixun Lan <dlan@...too.org>, 
 Alex Elder <elder@...cstar.com>, Troy Mitchell <troymitchell988@...il.com>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev, 
 Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: [PATCH 4/6] i2c: spacemit: check SDA instead of SCL after bus
 reset

After calling spacemit_i2c_conditionally_reset_bus(),
the controller should ensure that the SDA line is release
before proceeding.

Previously, the driver checked the SCL line instead,
which does not guarantee that the bus is truly idle.

This patch changes the check to verify SDA. This ensures
proper bus recovery and avoids potential communication errors
after a conditional reset.

Fixes: 5ea558473fa31 ("i2c: spacemit: add support for SpacemiT K1 SoC")
Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
---
 drivers/i2c/busses/i2c-k1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
index c1656b78f1681729ccc2ebca6e290259d14889d9..4d78ee7b6929ee43771e500d4f85d9e55e68b221 100644
--- a/drivers/i2c/busses/i2c-k1.c
+++ b/drivers/i2c/busses/i2c-k1.c
@@ -172,9 +172,9 @@ static void spacemit_i2c_conditionally_reset_bus(struct spacemit_i2c_dev *i2c)
 	spacemit_i2c_reset(i2c);
 	usleep_range(10, 20);
 
-	/* check scl status again */
+	/* check sda again here */
 	status = readl(i2c->base + SPACEMIT_IBMR);
-	if (!(status & SPACEMIT_BMR_SCL))
+	if (!(status & SPACEMIT_BMR_SDA))
 		dev_warn_ratelimited(i2c->dev, "unit reset failed\n");
 }
 

-- 
2.50.1