[Intel-gfx] [PATCH 1/2] pwm: lpss: Make builtin and add lookup-table so that i915 can find the pwm_backlight

Hans de Goede hdegoede at redhat.com
Fri Dec 2 10:17:35 UTC 2016


The primary consumer of the lpss pwm is the i915 kms driver, but
currently that driver cannot get the pwm because i915 platforms are
not using devicetree and pwm-lpss does not call pwm_add_table.

Another problem is that i915 does not support get_pwm returning
-EPROBE_DEFER and i915's init is very complex and this is almost
impossible to fix.

This commit changes the PWM_LPSS Kconfig from a tristate to a bool, so
that when the i915 driver loads the lpss pwm will be available avoiding
the -EPROBE_DEFER issue. Note that this is identical to how the same
problem was solved for the pwm-crc driver.

Being builtin also allows calling pwm_add_table directly from the
pwm-lpss code, otherwise the pwm_add_table call would need to be put
somewhere else to ensure it happens before i915 calls pwm_get,
even if i915 would support -EPROBE_DEFER.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/pwm/Kconfig    | 12 +++---------
 drivers/pwm/pwm-lpss.c | 11 +++++++++++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index bf01288..cda31ea 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -240,28 +240,22 @@ config PWM_LPC32XX
 	  will be called pwm-lpc32xx.
 
 config PWM_LPSS
-	tristate
+	bool
 
 config PWM_LPSS_PCI
-	tristate "Intel LPSS PWM PCI driver"
+	bool "Intel LPSS PWM PCI driver"
 	depends on X86 && PCI
 	select PWM_LPSS
 	help
 	  The PCI driver for Intel Low Power Subsystem PWM controller.
 
-	  To compile this driver as a module, choose M here: the module
-	  will be called pwm-lpss-pci.
-
 config PWM_LPSS_PLATFORM
-	tristate "Intel LPSS PWM platform driver"
+	bool "Intel LPSS PWM platform driver"
 	depends on X86 && ACPI
 	select PWM_LPSS
 	help
 	  The platform driver for Intel Low Power Subsystem PWM controller.
 
-	  To compile this driver as a module, choose M here: the module
-	  will be called pwm-lpss-platform.
-
 config PWM_MESON
 	tristate "Amlogic Meson PWM driver"
 	depends on ARCH_MESON
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 72c0bce..b4d8835 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -161,6 +161,12 @@ static const struct pwm_ops pwm_lpss_ops = {
 	.owner = THIS_MODULE,
 };
 
+/* PWM consumed by the Intel GFX */
+static struct pwm_lookup pwm_lpss_lookup[] = {
+	PWM_LOOKUP("pwm-lpss", 0, "0000:00:02.0", "pwm_backlight", 0,
+		   PWM_POLARITY_NORMAL),
+};
+
 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 				     const struct pwm_lpss_boardinfo *info)
 {
@@ -193,12 +199,17 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 		return ERR_PTR(ret);
 	}
 
+	/* Add lookup table for pwm_backlight */
+	pwm_lpss_lookup[0].provider = dev_name(dev);
+	pwm_add_table(pwm_lpss_lookup, ARRAY_SIZE(pwm_lpss_lookup));
+
 	return lpwm;
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
 
 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 {
+	pwm_remove_table(pwm_lpss_lookup, ARRAY_SIZE(pwm_lpss_lookup));
 	return pwmchip_remove(&lpwm->chip);
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
-- 
2.9.3



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