linux-kernel - [PATCH v4] i2c: rk3x: fix bug that cause transfer fails in master receive mode

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Message-Id: <1408730452-3552-1-git-send-email-addy.ke@rock-chips.com>
Date:	Sat, 23 Aug 2014 02:00:52 +0800
From:	Addy Ke <addy.ke@...k-chips.com>
To:	wsa@...-dreams.de, max.schwarz@...ine.de, heiko@...ech.de,
	olof@...om.net, dianders@...omium.org, dmitry.torokhov@...il.com
Cc:	sergei.shtylyov@...entembedded.com, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, cf@...k-chips.com,
	xjq@...k-chips.com, huangtao@...k-chips.com, zyw@...k-chips.com,
	yzq@...k-chips.com, hj@...k-chips.com, kever.yang@...k-chips.com,
	hl@...k-chips.com, caesar.wang@...k-chips.com,
	zhengsq@...k-chips.com, Addy Ke <addy.ke@...k-chips.com>
Subject: [PATCH v4] i2c: rk3x: fix bug that cause transfer fails in master receive mode

In rk3x SOC, the I2C controller can receive/transmit up to 32 bytes data
in one chunk, so the size of data to be write/read to/from TXDATAx/RXDATAx
must be less than or equal 32 bytes at a time.

Tested on rk3288-pinky board, elan receive 158 bytes data.

Suggested-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Addy Ke <addy.ke@...k-chips.com>
Acked-by: Max Schwarz <max.schwarz@...ine.de>
---
Changes in v2:
- Use cleaner syntax as suggested by Sergei.
- Update commit message as suggested by Wolfram.

Changes in v3:
- fix typo: maste --> master and double spaces after 'len'
 drivers/i2c/busses/i2c-rk3x.c | 4 ++++

Changes in v4:
- remove unlikely() annotations, suggested by Dmitry Torokhov

diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
index b8b2b89..31de730 100644
--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -323,6 +323,10 @@ static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
 	/* ack interrupt */
 	i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
 
+	/* Can only handle a maximum of 32 bytes at a time */
+	if (len > 32)
+		len = 32;
+
 	/* read the data from receive buffer */
 	for (i = 0; i < len; ++i) {
 		if (i % 4 == 0)
-- 
1.8.3.2


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