queue-5.1/mfd-twl6040-fix-device-init-errors-for-accctl-regist.patch

   1 From ebd40204c2214df8ed1d638d8d9d01d634218913 Mon Sep 17 00:00:00 2001
   2 From: Tony Lindgren <tony@atomide.com>
   3 Date: Thu, 14 Feb 2019 08:03:45 -0800
   4 Subject: mfd: twl6040: Fix device init errors for ACCCTL register
   5
   6 [ Upstream commit 48171d0ea7caccf21c9ee3ae75eb370f2a756062 ]
   7
   8 I noticed that we can get a -EREMOTEIO errors on at least omap4 duovero:
   9
  10 twl6040 0-004b: Failed to write 2d = 19: -121
  11
  12 And then any following register access will produce errors.
  13
  14 There 2d offset above is register ACCCTL that gets written on twl6040
  15 powerup. With error checking added to the related regcache_sync() call,
  16 the -EREMOTEIO error is reproducable on twl6040 powerup at least
  17 duovero.
  18
  19 To fix the error, we need to wait until twl6040 is accessible after the
  20 powerup. Based on tests on omap4 duovero, we need to wait over 8ms after
  21 powerup before register write will complete without failures. Let's also
  22 make sure we warn about possible errors too.
  23
  24 Note that we have twl6040_patch[] reg_sequence with the ACCCTL register
  25 configuration and regcache_sync() will write the new value to ACCCTL.
  26
  27 Signed-off-by: Tony Lindgren <tony@atomide.com>
  28 Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
  29 Signed-off-by: Lee Jones <lee.jones@linaro.org>
  30 Signed-off-by: Sasha Levin <sashal@kernel.org>
  31 ---
  32  drivers/mfd/twl6040.c | 13 ++++++++++++-
  33  1 file changed, 12 insertions(+), 1 deletion(-)
  34
  35 diff --git a/drivers/mfd/twl6040.c b/drivers/mfd/twl6040.c
  36 index 7c3c5fd5fcd0..86052c5c6069 100644
  37 --- a/drivers/mfd/twl6040.c
  38 +++ b/drivers/mfd/twl6040.c
  39 @@ -322,8 +322,19 @@ int twl6040_power(struct twl6040 *twl6040, int on)
  40                         }
  41                 }
  42
  43 +               /*
  44 +                * Register access can produce errors after power-up unless we
  45 +                * wait at least 8ms based on measurements on duovero.
  46 +                */
  47 +               usleep_range(10000, 12000);
  48 +
  49                 /* Sync with the HW */
  50 -               regcache_sync(twl6040->regmap);
  51 +               ret = regcache_sync(twl6040->regmap);
  52 +               if (ret) {
  53 +                       dev_err(twl6040->dev, "Failed to sync with the HW: %i\n",
  54 +                               ret);
  55 +                       goto out;
  56 +               }
  57
  58                 /* Default PLL configuration after power up */
  59                 twl6040->pll = TWL6040_SYSCLK_SEL_LPPLL;
  60 --
  61 2.20.1
  62