Patch "ACPI / LPSS: Only call pwm_add_table() for the first PWM controller" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

ACPI / LPSS: Only call pwm_add_table() for the first PWM controller

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
acpi-lpss-only-call-pwm_add_table-for-the-first-pwm-controller.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Hans de Goede <[email protected]>
Date: Thu, 6 Jul 2017 18:49:27 +0200
Subject: ACPI / LPSS: Only call pwm_add_table() for the first PWM controller

From: Hans de Goede <[email protected]>

commit dd242a080d178c36442a0bb28b6acf6f126d0569 upstream.

At least on the UP board SBC both PWMs are enabled leading to us trying to add the same pwm_lookup twice, which leads to the following:

[    0.902224] list_add double add: new=ffffffffb8efd400,
               prev=ffffffffb8efd400, next=ffffffffb8eeede0.
[    0.912466] ------------[ cut here ]------------
[    0.917624] kernel BUG at lib/list_debug.c:31!
[    0.922588] invalid opcode: 0000 [#1] SMP
...
[    1.027450] Call Trace:
[    1.030185]  pwm_add_table+0x4c/0x90
[    1.034181]  bsw_pwm_setup+0x1a/0x20
[    1.038175]  acpi_lpss_create_device+0xfe/0x420

...

This commit fixes this by only calling pwm_add_table() for the first PWM controller (which is the one used for the backlight).

---
 drivers/acpi/acpi_lpss.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

@@ -85,6 +85,7 @@ static const struct lpss_device_desc lps
 };
 
 struct lpss_private_data {
+	struct acpi_device *adev;
 	void __iomem *mmio_base;
 	resource_size_t mmio_size;
 	unsigned int fixed_clk_rate;

@@ -155,6 +156,12 @@ static struct pwm_lookup byt_pwm_lookup[
 
 static void byt_pwm_setup(struct lpss_private_data *pdata)
 {
+	struct acpi_device *adev = pdata->adev;
+
+	/* Only call pwm_add_table for the first PWM controller */
+	if (!adev->pnp.unique_id || strcmp(adev->pnp.unique_id, "1"))
+		return;
+
 	if (!acpi_dev_present("INT33FD", NULL, -1))
 		pwm_add_table(byt_pwm_lookup, ARRAY_SIZE(byt_pwm_lookup));
 }

@@ -180,6 +187,12 @@ static struct pwm_lookup bsw_pwm_lookup[
 
 static void bsw_pwm_setup(struct lpss_private_data *pdata)
 {
+	struct acpi_device *adev = pdata->adev;
+
+	/* Only call pwm_add_table for the first PWM controller */
+	if (!adev->pnp.unique_id || strcmp(adev->pnp.unique_id, "1"))
+		return;
+
 	pwm_add_table(bsw_pwm_lookup, ARRAY_SIZE(bsw_pwm_lookup));
 }
 

@@ -456,6 +469,7 @@ static int acpi_lpss_create_device(struc
 		goto err_out;
 	}
 
+	pdata->adev = adev;
 	pdata->dev_desc = dev_desc;
 
 	if (dev_desc->setup)

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/acpi-lpss-only-call-pwm_add_table-for-the-first-pwm-controller.patch