5.4-stable review patch. If anyone has any objections, please let me know.
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From: Leilk.Liu leilk.liu@mediatek.com
[ Upstream commit b492183652808e0f389272bf63dc836241b287ff ]
The old IC does not support the I2C_MASTER_WRRD (write-then-read) function, but the current code’s handling of i2c->auto_restart may potentially lead to entering the I2C_MASTER_WRRD software flow, resulting in unexpected bugs.
Instead of repurposing the auto_restart flag, add a separate flag to signal I2C_MASTER_WRRD operations.
Also fix handling of msgs. If the operation (i2c->op) is I2C_MASTER_WRRD, then the msgs pointer is incremented by 2. For all other operations, msgs is simply incremented by 1.
Fixes: b2ed11e224a2 ("I2C: mediatek: Add driver for MediaTek MT8173 I2C controller") Signed-off-by: Leilk.Liu leilk.liu@mediatek.com Suggested-by: Chen-Yu Tsai wenst@chromium.org Reviewed-by: Chen-Yu Tsai wenst@chromium.org Signed-off-by: Wolfram Sang wsa+renesas@sang-engineering.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-mt65xx.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c index 5587e7c549c4f..2b56ad08efed1 100644 --- a/drivers/i2c/busses/i2c-mt65xx.c +++ b/drivers/i2c/busses/i2c-mt65xx.c @@ -782,6 +782,7 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, { int ret; int left_num = num; + bool write_then_read_en = false; struct mtk_i2c *i2c = i2c_get_adapdata(adap);
ret = mtk_i2c_clock_enable(i2c); @@ -795,6 +796,7 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, if (!(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD) && msgs[0].addr == msgs[1].addr) { i2c->auto_restart = 0; + write_then_read_en = true; } }
@@ -818,12 +820,10 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, else i2c->op = I2C_MASTER_WR;
- if (!i2c->auto_restart) { - if (num > 1) { - /* combined two messages into one transaction */ - i2c->op = I2C_MASTER_WRRD; - left_num--; - } + if (write_then_read_en) { + /* combined two messages into one transaction */ + i2c->op = I2C_MASTER_WRRD; + left_num--; }
/* always use DMA mode. */ @@ -831,7 +831,10 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, if (ret < 0) goto err_exit;
- msgs++; + if (i2c->op == I2C_MASTER_WRRD) + msgs += 2; + else + msgs++; } /* the return value is number of executed messages */ ret = num;