RE: [PATCH] pinctrl: intel: Only restore pins that are used by the driver

[<Mario.Limonciello@dell.com>]

> Dell XPS 13 (and maybe some others) uses a GPIO (CPU_GP_1) during
> suspend
> to explicitly disable USB touchscreen interrupt. This is done to prevent
> situation where the lid is closed the touchscreen is left functional.
> 
> The pinctrl driver (wrongly) assumes it owns all pins which are owned by
> host and not locked down. It is perfectly fine for BIOS to use those pins
> as it is also considered as host in this context.
> 
> What happens is that when the lid of Dell XPS 13 is closed, the BIOS
> configures CPU_GP_1 low disabling the touchscreen interrupt. During
> resume
> we restore all host owned pins to the known state which includes CPU_GP_1
> and this overwrites what the BIOS has programmed there causing the
> touchscreen to fail as no interrupts are reaching the CPU anymore.
> 
> Fix this by restoring only those pins we know are explicitly requested by
> the kernel one way or other.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=176361
> Reported-by: AceLan Kao <acelan.kao@canonical.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> AceLan,
> 
> Can you try this one as well? It should do prevent the driver from messing
> the pins used by the BIOS.
> 
>  drivers/pinctrl/intel/pinctrl-intel.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-
> intel.c
> index 257cab129692..2b5b20bf7d99 100644
> --- a/drivers/pinctrl/intel/pinctrl-intel.c
> +++ b/drivers/pinctrl/intel/pinctrl-intel.c
> @@ -19,6 +19,7 @@
>  #include <linux/pinctrl/pinconf.h>
>  #include <linux/pinctrl/pinconf-generic.h>
> 
> +#include "../core.h"
>  #include "pinctrl-intel.h"
> 
>  /* Offset from regs */
> @@ -1079,6 +1080,26 @@ int intel_pinctrl_remove(struct platform_device
> *pdev)
>  EXPORT_SYMBOL_GPL(intel_pinctrl_remove);
> 
>  #ifdef CONFIG_PM_SLEEP
> +static bool intel_pinctrl_should_save(struct intel_pinctrl *pctrl, unsigned
> pin)
> +{
> +	const struct pin_desc *pd = pin_desc_get(pctrl->pctldev, pin);
> +
> +	if (!pd || !intel_pad_usable(pctrl, pin))
> +		return false;
> +
> +	/*
> +	 * Only restore the pin if it is actually in use by the kernel (or
> +	 * by userspace). It is possible that some pins are used by the
> +	 * BIOS during resume and those are not always locked down so
> leave
> +	 * them alone.
> +	 */
> +	if (pd->mux_owner || pd->gpio_owner ||
> +	    gpiochip_line_is_irq(&pctrl->chip, pin))
> +		return true;
> +
> +	return false;
> +}
> +
>  int intel_pinctrl_suspend(struct device *dev)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> @@ -1092,7 +1113,7 @@ int intel_pinctrl_suspend(struct device *dev)
>  		const struct pinctrl_pin_desc *desc = &pctrl->soc->pins[i];
>  		u32 val;
> 
> -		if (!intel_pad_usable(pctrl, desc->number))
> +		if (!intel_pinctrl_should_save(pctrl, desc->number))
>  			continue;
> 
>  		val = readl(intel_get_padcfg(pctrl, desc->number,
> PADCFG0));
> @@ -1153,7 +1174,7 @@ int intel_pinctrl_resume(struct device *dev)
>  		void __iomem *padcfg;
>  		u32 val;
> 
> -		if (!intel_pad_usable(pctrl, desc->number))
> +		if (!intel_pinctrl_should_save(pctrl, desc->number))
>  			continue;
> 
>  		padcfg = intel_get_padcfg(pctrl, desc->number, PADCFG0);
> --
> 2.9.3

Mika,

After positive comments in this working properly and is accepted, would you 
consider submitting back to @stable as well?  It affects all kernel versions 
that carry intel pinctrl (IIRC back to 4.1?)

Thanks,