[PATCH 4.2.y-ckt 128/211] i2c: img-scb: do dummy writes before fifo access

[Kamal Mostafa]

4.2.8-ckt1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sifan Naeem <sifan.naeem@xxxxxxxxxx>

commit 2aefb1bd4101235be7d9f0d5ac8d56aa979f6081 upstream.

Move scb_wr_rd_fence to before reading from fifo and writing to
fifo to make sure the the first read/write is done after the required
number of cycles.

Fixes: commit 27bce457d588 ("i2c: img-scb: Add Imagination Technologies I2C SCB driver")
Signed-off-by: Sifan Naeem <sifan.naeem@xxxxxxxxxx>
Acked-by: James Hogan <james.hogan@xxxxxxxxxx>
Reviewed-by: James Hartley <james.hartley@xxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 drivers/i2c/busses/i2c-img-scb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
index 5c3c615..0368d91 100644
--- a/drivers/i2c/busses/i2c-img-scb.c
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -534,6 +534,7 @@ static void img_i2c_read_fifo(struct img_i2c *i2c)
 		u32 fifo_status;
 		u8 data;
 
+		img_i2c_wr_rd_fence(i2c);
 		fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
 		if (fifo_status & FIFO_READ_EMPTY)
 			break;
@@ -542,7 +543,6 @@ static void img_i2c_read_fifo(struct img_i2c *i2c)
 		*i2c->msg.buf = data;
 
 		img_i2c_writel(i2c, SCB_READ_FIFO_REG, 0xff);
-		img_i2c_wr_rd_fence(i2c);
 		i2c->msg.len--;
 		i2c->msg.buf++;
 	}
@@ -554,12 +554,12 @@ static void img_i2c_write_fifo(struct img_i2c *i2c)
 	while (i2c->msg.len) {
 		u32 fifo_status;
 
+		img_i2c_wr_rd_fence(i2c);
 		fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
 		if (fifo_status & FIFO_WRITE_FULL)
 			break;
 
 		img_i2c_writel(i2c, SCB_WRITE_DATA_REG, *i2c->msg.buf);
-		img_i2c_wr_rd_fence(i2c);
 		i2c->msg.len--;
 		i2c->msg.buf++;
 	}
-- 
1.9.1

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