The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 29c2c6aa32405dfee4a29911a51ba133edcedb0f Mon Sep 17 00:00:00 2001
From: Andy Shevchenko andriy.shevchenko@linux.intel.com Date: Mon, 14 Oct 2019 12:51:04 +0300 Subject: [PATCH] pinctrl: intel: Avoid potential glitches if pin is in GPIO mode
When consumer requests a pin, in order to be on the safest side, we switch it first to GPIO mode followed by immediate transition to the input state. Due to posted writes it's luckily to be a single I/O transaction.
However, if firmware or boot loader already configures the pin to the GPIO mode, user expects no glitches for the requested pin. We may check if the pin is pre-configured and leave it as is till the actual consumer toggles its state to avoid glitches.
Fixes: 7981c0015af2 ("pinctrl: intel: Add Intel Sunrisepoint pin controller and GPIO support") Depends-on: f5a26acf0162 ("pinctrl: intel: Initialize GPIO properly when used through irqchip") Cc: stable@vger.kernel.org Cc: fei.yang@intel.com Reported-by: Oliver Barta oliver.barta@aptiv.com Reported-by: Malin Jonsson malin.jonsson@ericsson.com Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Signed-off-by: Mika Westerberg mika.westerberg@linux.intel.com
diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c index bc013599a9a3..83981ad66a71 100644 --- a/drivers/pinctrl/intel/pinctrl-intel.c +++ b/drivers/pinctrl/intel/pinctrl-intel.c @@ -52,6 +52,7 @@ #define PADCFG0_GPIROUTNMI BIT(17) #define PADCFG0_PMODE_SHIFT 10 #define PADCFG0_PMODE_MASK GENMASK(13, 10) +#define PADCFG0_PMODE_GPIO 0 #define PADCFG0_GPIORXDIS BIT(9) #define PADCFG0_GPIOTXDIS BIT(8) #define PADCFG0_GPIORXSTATE BIT(1) @@ -332,7 +333,7 @@ static void intel_pin_dbg_show(struct pinctrl_dev *pctldev, struct seq_file *s, cfg1 = readl(intel_get_padcfg(pctrl, pin, PADCFG1));
mode = (cfg0 & PADCFG0_PMODE_MASK) >> PADCFG0_PMODE_SHIFT; - if (!mode) + if (mode == PADCFG0_PMODE_GPIO) seq_puts(s, "GPIO "); else seq_printf(s, "mode %d ", mode); @@ -458,6 +459,11 @@ static void __intel_gpio_set_direction(void __iomem *padcfg0, bool input) writel(value, padcfg0); }
+static int intel_gpio_get_gpio_mode(void __iomem *padcfg0) +{ + return (readl(padcfg0) & PADCFG0_PMODE_MASK) >> PADCFG0_PMODE_SHIFT; +} + static void intel_gpio_set_gpio_mode(void __iomem *padcfg0) { u32 value; @@ -491,7 +497,20 @@ static int intel_gpio_request_enable(struct pinctrl_dev *pctldev, }
padcfg0 = intel_get_padcfg(pctrl, pin, PADCFG0); + + /* + * If pin is already configured in GPIO mode, we assume that + * firmware provides correct settings. In such case we avoid + * potential glitches on the pin. Otherwise, for the pin in + * alternative mode, consumer has to supply respective flags. + */ + if (intel_gpio_get_gpio_mode(padcfg0) == PADCFG0_PMODE_GPIO) { + raw_spin_unlock_irqrestore(&pctrl->lock, flags); + return 0; + } + intel_gpio_set_gpio_mode(padcfg0); + /* Disable TX buffer and enable RX (this will be input) */ __intel_gpio_set_direction(padcfg0, true);