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    Subject[PATCH 4.2.y-ckt 128/211] i2c: img-scb: do dummy writes before fifo access
    Date
    4.2.8-ckt1 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Sifan Naeem <sifan.naeem@imgtec.com>

    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@imgtec.com>
    Acked-by: James Hogan <james.hogan@imgtec.com>
    Reviewed-by: James Hartley <james.hartley@imgtec.com>
    Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    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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