pinctrl: baytrail: Really serialize all register accesses
Commit 39ce8150 ("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@vger.kernel.org Fixes: 39ce8150 ("pinctrl: baytrail: Serialize all register access") Signed-off-by:Hans de Goede <hdegoede@redhat.com> Acked-by: