Add patches from 4.20 fixing black screen on CHT devices with i915.fastboot=1

2 files changed, 531 insertions, 0 deletions

diff --git a/cherrytrail-pwm-lpss-fixes.patch b/cherrytrail-pwm-lpss-fixes.patch
new file mode 100644
index 000000000..958dd7e74
--- /dev/null
+++ b/cherrytrail-pwm-lpss-fixes.patch
@@ -0,0 +1,525 @@
+From 9e2ef73d9d72ab312bef34ba318fdcb77facb1f0 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Mon, 27 Aug 2018 09:47:42 +0200
+Subject: [PATCH 1/7] pwm: lpss: Add ACPI HID for second PWM controller on
+ Cherry Trail devices
+
+The second PWM controller on Cherry Trail devices uses a separate ACPI
+HID: "80862289", add this so that the driver will properly bind to the
+second PWM controller.
+
+The second PWM controller is usually not used, the main thing gained by
+this is properly putting the PWM controller in D3 on suspend.
+
+Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+ drivers/pwm/pwm-lpss-platform.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
+index 5561b9e190f8..7304f36ee715 100644
+--- a/drivers/pwm/pwm-lpss-platform.c
++++ b/drivers/pwm/pwm-lpss-platform.c
+@@ -81,6 +81,7 @@ static SIMPLE_DEV_PM_OPS(pwm_lpss_platform_pm_ops,
+ static const struct acpi_device_id pwm_lpss_acpi_match[] = {
+ 	{ "80860F09", (unsigned long)&pwm_lpss_byt_info },
+ 	{ "80862288", (unsigned long)&pwm_lpss_bsw_info },
++	{ "80862289", (unsigned long)&pwm_lpss_bsw_info },
+ 	{ "80865AC8", (unsigned long)&pwm_lpss_bxt_info },
+ 	{ },
+ };
+-- 
+2.19.1
+
+From f215ee5bd62ab40ee34c318df1af61991dead98d Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Tue, 11 Sep 2018 16:07:41 +0200
+Subject: [PATCH 2/7] pwm: lpss: Move struct pwm_lpss_chip definition to the
+ header file
+
+Move struct pwm_lpss_chip definition from pwm-lpss.c to pwm-lpss.h,
+so that the pci/platform drivers can access the info member
+(struct pwm_lpss_boardinfo *).
+
+This is a preparation patch for adding platform specific quirks, which
+the drivers need access to, to pwm_lpss_boardinfo.
+
+Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+Changes in v4:
+-No changes in v4 of this patch-set
+
+Changes in v3:
+-There was no v3, but I accidentally put v3 in the Subject of the v2
+ patches, so lets skip v3
+
+Changes in v2:
+-No changes in v2 of this patch-set
+---
+ drivers/pwm/pwm-lpss.c | 9 ---------
+ drivers/pwm/pwm-lpss.h | 9 ++++++++-
+ 2 files changed, 8 insertions(+), 10 deletions(-)
+
+diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
+index 4721a264bac2..e602835fd6de 100644
+--- a/drivers/pwm/pwm-lpss.c
++++ b/drivers/pwm/pwm-lpss.c
+@@ -32,15 +32,6 @@
+ /* Size of each PWM register space if multiple */
+ #define PWM_SIZE			0x400
+ 
+-#define MAX_PWMS			4
+-
+-struct pwm_lpss_chip {
+-	struct pwm_chip chip;
+-	void __iomem *regs;
+-	const struct pwm_lpss_boardinfo *info;
+-	u32 saved_ctrl[MAX_PWMS];
+-};
+-
+ static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
+ {
+ 	return container_of(chip, struct pwm_lpss_chip, chip);
+diff --git a/drivers/pwm/pwm-lpss.h b/drivers/pwm/pwm-lpss.h
+index 7a4238ad1fcb..8f029ed263af 100644
+--- a/drivers/pwm/pwm-lpss.h
++++ b/drivers/pwm/pwm-lpss.h
+@@ -16,7 +16,14 @@
+ #include <linux/device.h>
+ #include <linux/pwm.h>
+ 
+-struct pwm_lpss_chip;
++#define MAX_PWMS			4
++
++struct pwm_lpss_chip {
++	struct pwm_chip chip;
++	void __iomem *regs;
++	const struct pwm_lpss_boardinfo *info;
++	u32 saved_ctrl[MAX_PWMS];
++};
+ 
+ struct pwm_lpss_boardinfo {
+ 	unsigned long clk_rate;
+-- 
+2.19.1
+
+From eb73756876f92ad0da4259400bce50881cb332b7 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Mon, 10 Sep 2018 15:30:58 +0200
+Subject: [PATCH 3/7] pwm: lpss: Check PWM powerstate after resume on Cherry
+ Trail devices
+
+The _PS0 method for the integrated graphics on some Cherry Trail devices
+(observed on a HP Pavilion X2 10-p0XX) turns on the PWM chip (puts it in
+D0), causing an inconsistency between the state the pm-core thinks it is
+in (left runtime suspended as it was before the suspend/resume) and the
+state it actually is in.
+
+Interestingly enough this is done on a device where the pwm controller is
+not used for the backlight at all, since it uses an eDP panel. On devices
+where the PWM is used this is not a problem since we will resume it
+ourselves anyways.
+
+This inconsistency causes us to never suspend the pwm controller again,
+which causes the device to not be able to reach S0ix states when suspended.
+
+This commit adds a resume-complete handler, which when we think the device
+is still run-time suspended checks the actual power-state and if necessary
+updates the rpm-core's internal state.
+
+This fixes the Pavilion X2 10-p0XX not reaching S0ix states when suspended.
+
+Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+Changes in v4:
+-Use acpi_device_get_power() instead of manually calling _PSC
+
+Changes in v3:
+-There was no v3, but I accidentally put v3 in the Subject of the v2
+ patches, so lets skip v3
+
+Changes in v2:
+-Do the pm_runtime_en/disable before/after checking the power-state
+---
+ drivers/pwm/pwm-lpss-platform.c | 25 ++++++++++++++++++++++---
+ drivers/pwm/pwm-lpss.h          |  2 ++
+ 2 files changed, 24 insertions(+), 3 deletions(-)
+
+diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
+index 7304f36ee715..b6edf8af26cc 100644
+--- a/drivers/pwm/pwm-lpss-platform.c
++++ b/drivers/pwm/pwm-lpss-platform.c
+@@ -30,6 +30,7 @@ static const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
+ 	.clk_rate = 19200000,
+ 	.npwm = 1,
+ 	.base_unit_bits = 16,
++	.check_power_on_resume = true,
+ };
+ 
+ /* Broxton */
+@@ -74,9 +75,27 @@ static int pwm_lpss_remove_platform(struct platform_device *pdev)
+ 	return pwm_lpss_remove(lpwm);
+ }
+ 
+-static SIMPLE_DEV_PM_OPS(pwm_lpss_platform_pm_ops,
+-			 pwm_lpss_suspend,
+-			 pwm_lpss_resume);
++static void pwm_lpss_complete(struct device *dev)
++{
++	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
++	int ret, state;
++
++	/* The PWM may be turned on by AML code, update our state to match */
++	if (pm_runtime_suspended(dev) && lpwm->info->check_power_on_resume) {
++		pm_runtime_disable(dev);
++
++		ret = acpi_device_get_power(ACPI_COMPANION(dev), &state);
++		if (ret == 0 && state == ACPI_STATE_D0)
++			pm_runtime_set_active(dev);
++
++		pm_runtime_enable(dev);
++	}
++}
++
++static const struct dev_pm_ops pwm_lpss_platform_pm_ops = {
++	.complete = pwm_lpss_complete,
++	SET_SYSTEM_SLEEP_PM_OPS(pwm_lpss_suspend, pwm_lpss_resume)
++};
+ 
+ static const struct acpi_device_id pwm_lpss_acpi_match[] = {
+ 	{ "80860F09", (unsigned long)&pwm_lpss_byt_info },
+diff --git a/drivers/pwm/pwm-lpss.h b/drivers/pwm/pwm-lpss.h
+index 8f029ed263af..1a2575d25bea 100644
+--- a/drivers/pwm/pwm-lpss.h
++++ b/drivers/pwm/pwm-lpss.h
+@@ -30,6 +30,8 @@ struct pwm_lpss_boardinfo {
+ 	unsigned int npwm;
+ 	unsigned long base_unit_bits;
+ 	bool bypass;
++	/* Some devices have AML code messing with the state underneath us */
++	bool check_power_on_resume;
+ };
+ 
+ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
+-- 
+2.19.1
+
+From 0a2e85765305e9fc376d0153aa9747b5d58cc804 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Mon, 24 Sep 2018 20:57:43 +0200
+Subject: [PATCH 4/7] pwm: lpss: Release runtime-pm reference from the driver's
+ remove callback
+
+For each pwm output which gets enabled through pwm_lpss_apply(), we do a
+pm_runtime_get_sync().
+
+This commit adds pm_runtime_put() calls to pwm_lpss_remove() to balance
+these when the driver gets removed with some of the outputs still enabled.
+
+Fixes: f080be27d7d9 ("pwm: lpss: Add support for runtime PM")
+Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+Changes in v2:
+-New patch in v2 of this patch-set replacing "pwm: lpss: Add
+ pwm_lpss_get_put_runtime_pm helper function"
+---
+ drivers/pwm/pwm-lpss.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
+index e602835fd6de..723ca9de8325 100644
+--- a/drivers/pwm/pwm-lpss.c
++++ b/drivers/pwm/pwm-lpss.c
+@@ -205,6 +205,12 @@ EXPORT_SYMBOL_GPL(pwm_lpss_probe);
+ 
+ int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
+ {
++	int i;
++
++	for (i = 0; i < lpwm->info->npwm; i++) {
++		if (pwm_is_enabled(&lpwm->chip.pwms[i]))
++			pm_runtime_put(lpwm->chip.dev);
++	}
+ 	return pwmchip_remove(&lpwm->chip);
+ }
+ EXPORT_SYMBOL_GPL(pwm_lpss_remove);
+-- 
+2.19.1
+
+From c3ffc28eeb4f9974380c4a85abfbb387d6d1cd8d Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Fri, 25 Nov 2016 09:45:19 +0100
+Subject: [PATCH 5/7] pwm: lpss: Add get_state callback
+
+Add a get_state callback so that the initial state correctly reflects
+the actual hardware state.
+
+Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Acked-by: Jani Nikula <jani.nikula@intel.com>
+Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+Changes in v2:
+-Stop using the dropped pwm_lpss_get_put_runtime_pm() helper
+---
+ drivers/pwm/pwm-lpss.c | 34 ++++++++++++++++++++++++++++++++++
+ 1 file changed, 34 insertions(+)
+
+diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
+index 723ca9de8325..ea93ef9f3672 100644
+--- a/drivers/pwm/pwm-lpss.c
++++ b/drivers/pwm/pwm-lpss.c
+@@ -159,8 +159,42 @@ static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ 	return 0;
+ }
+ 
++/* This function gets called once from pwmchip_add to get the initial state */
++static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
++			       struct pwm_state *state)
++{
++	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
++	unsigned long base_unit_range;
++	unsigned long long base_unit, freq, on_time_div;
++	u32 ctrl;
++
++	base_unit_range = BIT(lpwm->info->base_unit_bits);
++
++	ctrl = pwm_lpss_read(pwm);
++	on_time_div = 255 - (ctrl & PWM_ON_TIME_DIV_MASK);
++	base_unit = (ctrl >> PWM_BASE_UNIT_SHIFT) & (base_unit_range - 1);
++
++	freq = base_unit * lpwm->info->clk_rate;
++	do_div(freq, base_unit_range);
++	if (freq == 0)
++		state->period = NSEC_PER_SEC;
++	else
++		state->period = NSEC_PER_SEC / (unsigned long)freq;
++
++	on_time_div *= state->period;
++	do_div(on_time_div, 255);
++	state->duty_cycle = on_time_div;
++
++	state->polarity = PWM_POLARITY_NORMAL;
++	state->enabled = !!(ctrl & PWM_ENABLE);
++
++	if (state->enabled)
++		pm_runtime_get(chip->dev);
++}
++
+ static const struct pwm_ops pwm_lpss_ops = {
+ 	.apply = pwm_lpss_apply,
++	.get_state = pwm_lpss_get_state,
+ 	.owner = THIS_MODULE,
+ };
+ 
+-- 
+2.19.1
+
+From e96509f196d1229cf66b19ad9f3d7cd43a86bc9d Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Sat, 13 Oct 2018 00:04:12 +0200
+Subject: [PATCH 6/7] pwm: lpss: Force runtime-resume on suspend on Cherry
+ Trail
+
+On Cherry Trail devices under Windows the PWM controller used for the
+backlight is considered part of the GPU even though it is part of the LPSS
+block and thus is an entirely different independent hardware unit.
+
+Because of this on Cherry Trail the GPU's (GFX0 ACPI node) _PS3 and _PS0
+methods save and restore the PWM controller registers.
+
+If userspace blanks the screen before suspending, such as e.g. GNOME
+does, then the PWM controller will be runtime-suspended when the suspend
+starts. This causes the GFX0 _PS? methods to save a value of 0xffffffff
+for the PWM control register and to restore this value on resume.
+
+0xffffffff is not a valid value for the register and writing this causes
+problems such as e.g. a flickering backlight.
+
+This commit adds a prepare method to the dev_pm_ops and makes it return 0
+on Cherry Trail devices forcing a runtime-resume before other device's
+suspend methods run. This fixes the reading and writing back of 0xffffffff.
+
+Since we now always runtime-resume the device on suspend, it will be
+resumed on resume too and we no longer need to check for the GFX0 _PS0
+method having resumed it underneath us, so this commit removes the now no
+longer necessary complete dev_pm_op.
+
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+ drivers/pwm/pwm-lpss-platform.c | 24 +++++++++++-------------
+ drivers/pwm/pwm-lpss.h          |  7 +++++--
+ 2 files changed, 16 insertions(+), 15 deletions(-)
+
+diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
+index b6edf8af26cc..757230e1f575 100644
+--- a/drivers/pwm/pwm-lpss-platform.c
++++ b/drivers/pwm/pwm-lpss-platform.c
+@@ -30,7 +30,7 @@ static const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
+ 	.clk_rate = 19200000,
+ 	.npwm = 1,
+ 	.base_unit_bits = 16,
+-	.check_power_on_resume = true,
++	.other_devices_aml_touches_pwm_regs = true,
+ };
+ 
+ /* Broxton */
+@@ -61,6 +61,7 @@ static int pwm_lpss_probe_platform(struct platform_device *pdev)
+ 
+ 	platform_set_drvdata(pdev, lpwm);
+ 
++	dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_SMART_PREPARE);
+ 	pm_runtime_set_active(&pdev->dev);
+ 	pm_runtime_enable(&pdev->dev);
+ 
+@@ -75,25 +76,22 @@ static int pwm_lpss_remove_platform(struct platform_device *pdev)
+ 	return pwm_lpss_remove(lpwm);
+ }
+ 
+-static void pwm_lpss_complete(struct device *dev)
++static int pwm_lpss_prepare(struct device *dev)
+ {
+ 	struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
+-	int ret, state;
+ 
+-	/* The PWM may be turned on by AML code, update our state to match */
+-	if (pm_runtime_suspended(dev) && lpwm->info->check_power_on_resume) {
+-		pm_runtime_disable(dev);
++	/*
++	 * If other device's AML code touches the PWM regs on suspend/resume
++	 * force runtime-resume the PWM controller to allow this.
++	 */
++	if (lpwm->info->other_devices_aml_touches_pwm_regs)
++		return 0; /* Force runtime-resume */
+ 
+-		ret = acpi_device_get_power(ACPI_COMPANION(dev), &state);
+-		if (ret == 0 && state == ACPI_STATE_D0)
+-			pm_runtime_set_active(dev);
+-
+-		pm_runtime_enable(dev);
+-	}
++	return 1; /* If runtime-suspended leave as is */
+ }
+ 
+ static const struct dev_pm_ops pwm_lpss_platform_pm_ops = {
+-	.complete = pwm_lpss_complete,
++	.prepare = pwm_lpss_prepare,
+ 	SET_SYSTEM_SLEEP_PM_OPS(pwm_lpss_suspend, pwm_lpss_resume)
+ };
+ 
+diff --git a/drivers/pwm/pwm-lpss.h b/drivers/pwm/pwm-lpss.h
+index 1a2575d25bea..3236be835bd9 100644
+--- a/drivers/pwm/pwm-lpss.h
++++ b/drivers/pwm/pwm-lpss.h
+@@ -30,8 +30,11 @@ struct pwm_lpss_boardinfo {
+ 	unsigned int npwm;
+ 	unsigned long base_unit_bits;
+ 	bool bypass;
+-	/* Some devices have AML code messing with the state underneath us */
+-	bool check_power_on_resume;
++	/*
++	 * On some devices the _PS0/_PS3 AML code of the GPU (GFX0) device
++	 * messes with the PWM0 controllers state,
++	 */
++	bool other_devices_aml_touches_pwm_regs;
+ };
+ 
+ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
+-- 
+2.19.1
+
+From f249418a3a4f123a37c389378f289a7baea95332 Mon Sep 17 00:00:00 2001
+From: Hans de Goede <hdegoede@redhat.com>
+Date: Fri, 12 Oct 2018 21:39:53 +0200
+Subject: [PATCH 7/7] pwm: lpss: Only set update bit if we are actually
+ changing the settings
+
+According to the datasheet the update bit must be set if the on-time-div
+or the base-unit changes.
+
+Now that we properly order device resume on Cherry Trail so that the GFX0
+_PS0 method no longer exits with an error, we end up with a sequence of
+events where we are writing the same values twice in a row.
+
+First the _PS0 method restores the duty cycle of 0% the GPU driver set
+on suspend and then the GPU driver first updates just the enabled bit in
+the pwm_state from 0 to 1, causing us to write the same values again,
+before restoring the pre-suspend duty-cycle in a separate pwm_apply call.
+
+When writing the update bit the second time, without changing any of
+the values the update bit clears immediately / instantly, instead of
+staying 1 for a while as usual. After this the next setting of the update
+bit seems to be ignored, causing the restoring of the pre-suspend
+duty-cycle to not get applied. This makes the backlight come up with
+a 0% dutycycle after suspend/resume.
+
+Any further brightness changes after this do work.
+
+This commit moves the setting of the update bit into pwm_lpss_prepare()
+and only sets the bit if we have actually changed any of the values.
+
+This avoids the setting of the update bit the second time we configure
+the PWM to 0% dutycycle, this fixes the backlight coming up with 0%
+duty-cycle after a suspend/resume.
+
+Signed-off-by: Hans de Goede <hdegoede@redhat.com>
+---
+ drivers/pwm/pwm-lpss.c | 12 +++++++-----
+ 1 file changed, 7 insertions(+), 5 deletions(-)
+
+diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
+index ea93ef9f3672..2ac3a2aa9e53 100644
+--- a/drivers/pwm/pwm-lpss.c
++++ b/drivers/pwm/pwm-lpss.c
+@@ -88,7 +88,7 @@ static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm,
+ 	unsigned long long on_time_div;
+ 	unsigned long c = lpwm->info->clk_rate, base_unit_range;
+ 	unsigned long long base_unit, freq = NSEC_PER_SEC;
+-	u32 ctrl;
++	u32 orig_ctrl, ctrl;
+ 
+ 	do_div(freq, period_ns);
+ 
+@@ -105,13 +105,17 @@ static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm,
+ 	do_div(on_time_div, period_ns);
+ 	on_time_div = 255ULL - on_time_div;
+ 
+-	ctrl = pwm_lpss_read(pwm);
++	orig_ctrl = ctrl = pwm_lpss_read(pwm);
+ 	ctrl &= ~PWM_ON_TIME_DIV_MASK;
+ 	ctrl &= ~(base_unit_range << PWM_BASE_UNIT_SHIFT);
+ 	base_unit &= base_unit_range;
+ 	ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
+ 	ctrl |= on_time_div;
+-	pwm_lpss_write(pwm, ctrl);
++
++	if (orig_ctrl != ctrl) {
++		pwm_lpss_write(pwm, ctrl);
++		pwm_lpss_write(pwm, ctrl | PWM_SW_UPDATE);
++	}
+ }
+ 
+ static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond)
+@@ -135,7 +139,6 @@ static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ 				return ret;
+ 			}
+ 			pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
+-			pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
+ 			pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false);
+ 			ret = pwm_lpss_wait_for_update(pwm);
+ 			if (ret) {
+@@ -148,7 +151,6 @@ static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ 			if (ret)
+ 				return ret;
+ 			pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
+-			pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
+ 			return pwm_lpss_wait_for_update(pwm);
+ 		}
+ 	} else if (pwm_is_enabled(pwm)) {
+-- 
+2.19.1
+
diff --git a/kernel.spec b/kernel.spec
index 281d7e8fa..82a735433 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -620,6 +620,9 @@ Patch506: cdrom-fix-improper-type-cast-which-can-leat-to-information-leak.patch
 # rhbz 1526312, patch is in 4.20, can be dropped on rebase
 Patch507: 0001-HID-i2c-hid-override-HID-descriptors-for-certain-dev.patch
 
+# Patches from 4.20 fixing black screen on CHT devices with i915.fastboot=1
+Patch508: cherrytrail-pwm-lpss-fixes.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1881,6 +1884,9 @@ fi
 #
 #
 %changelog
+* Fri Nov 16 2018 Hans de Goede <hdegoede@redhat.com>
+- Add patches from 4.20 fixing black screen on CHT devices with i915.fastboot=1
+
 * Thu Nov 15 2018 Hans de Goede <hdegoede@redhat.com>
 - Add patch fixing touchpads on some Apollo Lake devices not working (#1526312)