Hi,
On 19-11-2019 09:19, Mika Westerberg wrote:
On Mon, Nov 18, 2019 at 03:20:20PM +0100, Hans de Goede wrote:
Commit 39ce8150a079 ("pinctrl: baytrail: Serialize all register access")
added a spinlock around all register accesses because:
"There is a hardware issue in Intel Baytrail where concurrent GPIO register
access might result reads of 0xffffffff and writes might get dropped
completely."
Testing has shown that this does not catch all cases, there are still
2 problems remaining
1) The original fix uses a spinlock per byt_gpio device / struct,
additional testing has shown that this is not sufficient concurent
accesses to 2 different GPIO banks also suffer from the same problem.
This commit fixes this by moving to a single global lock.
2) The original fix did not add a lock around the register accesses in
the suspend/resume handling.
Since pinctrl-baytrail.c is using normal suspend/resume handlers,
interrupts are still enabled during suspend/resume handling. Nothing
should be using the GPIOs when they are being taken down, _but_ the
GPIOs themselves may still cause interrupts, which are likely to
use (read) the triggering GPIO. So we need to protect against
concurrent GPIO register accesses in the suspend/resume handlers too.
This commit fixes this by adding the missing spin_lock / unlock calls.
The 2 fixes together fix the Acer Switch 10 SW5-012 getting completely
confused after a suspend resume. The DSDT for this device has a bug
in its _LID method which reprograms the home and power button trigger-
flags requesting both high and low _level_ interrupts so the IRQs for
these 2 GPIOs continuously fire. This combined with the saving of
registers during suspend, triggers concurrent GPIO register accesses
resulting in saving 0xffffffff as pconf0 value during suspend and then
when restoring this on resume the pinmux settings get all messed up,
resulting in various I2C busses being stuck, the wifi no longer working
and often the tablet simply not coming out of suspend at all.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 39ce8150a079 ("pinctrl: baytrail: Serialize all register access")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/pinctrl/intel/pinctrl-baytrail.c | 81 +++++++++++++-----------
1 file changed, 44 insertions(+), 37 deletions(-)
diff --git a/drivers/pinctrl/intel/pinctrl-baytrail.c b/drivers/pinctrl/intel/pinctrl-baytrail.c
index b18336d42252..1b289f64c3a2 100644
--- a/drivers/pinctrl/intel/pinctrl-baytrail.c
+++ b/drivers/pinctrl/intel/pinctrl-baytrail.c
@@ -111,7 +111,6 @@ struct byt_gpio {
struct platform_device *pdev;
struct pinctrl_dev *pctl_dev;
struct pinctrl_desc pctl_desc;
- raw_spinlock_t lock;
const struct intel_pinctrl_soc_data *soc_data;
struct intel_community *communities_copy;
struct byt_gpio_pin_context *saved_context;
@@ -550,6 +549,8 @@ static const struct intel_pinctrl_soc_data *byt_soc_data[] = {
NULL
};
+static DEFINE_RAW_SPINLOCK(byt_gpio_lock);
Can we call it byt_lock instead? Following same convention we use in
chv.
Ok, v2 with this changed coming up.
Other than that looks good and definitely right thing to do. Thanks for
doing this Hans!
You are welcome. I must say that this was an interesting adventure :)
The interrupt storm issue on the Acer SW5-012 really managed to hit this bug
very reliably, resulting in all sorts of fun due to the pinmux settings
getting messed up.
Regards,
Hans
