target/linux/layerscape/patches-5.4/808-i2c-0007-i2c-imx-add-workaround-for-erratum-ERR010027.patch

   1 From 8e7e594b685f3fe44cd4803e3a4634bed897c2f7 Mon Sep 17 00:00:00 2001
   2 From: Zhang Ying-22455 <ying.zhang22455@nxp.com>
   3 Date: Fri, 14 Apr 2017 17:03:03 +0800
   4 Subject: [PATCH] i2c: imx: add workaround for erratum ERR010027
   5
   6 ERR010027: Attempting a start cycle while the bus is busy may
   7 generate a short clock pulse.
   8
   9 Software must ensure that the I2C BUS is idle by checking the
  10 bus busy before switching to master mode and attempting a Start
  11 cycle.
  12
  13 Signed-off-by: Zhang Ying-22455 <ying.zhang22455@nxp.com>
  14 ---
  15  drivers/i2c/busses/i2c-imx.c | 8 ++++++++
  16  1 file changed, 8 insertions(+)
  17
  18 --- a/drivers/i2c/busses/i2c-imx.c
  19 +++ b/drivers/i2c/busses/i2c-imx.c
  20 @@ -940,6 +940,14 @@ static int i2c_imx_xfer(struct i2c_adapt
  21                 enable_runtime_pm = true;
  22         }
  23
  24 +       /*
  25 +        * workround for ERR010027: ensure that the I2C BUS is idle
  26 +        * before switching to master mode and attempting a Start cycle
  27 +        */
  28 +       result =  i2c_imx_bus_busy(i2c_imx, 0);
  29 +       if (result)
  30 +               goto out;
  31 +
  32         result = pm_runtime_get_sync(i2c_imx->adapter.dev.parent);
  33         if (result < 0)
  34                 goto out;