[PATCH 3.16 122/366] ACPI / LPSS: Add missing prv_offset setting for byt/cht PWM devices

[Ben Hutchings]

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

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From: Hans de Goede <hdegoede@xxxxxxxxxx>

commit fdcb613d49321b5bf5d5a1bd0fba8e7c241dcc70 upstream.

The LPSS PWM device on on Bay Trail and Cherry Trail devices has a set
of private registers at offset 0x800, the current lpss_device_desc for
them already sets the LPSS_SAVE_CTX flag to have these saved/restored
over device-suspend, but the current lpss_device_desc was not setting
the prv_offset field, leading to the regular device registers getting
saved/restored instead.

This is causing the PWM controller to no longer work, resulting in a black
screen,  after a suspend/resume on systems where the firmware clears the
APB clock and reset bits at offset 0x804.

This commit fixes this by properly setting prv_offset to 0x800 for
the PWM devices.

Fixes: e1c748179754 ("ACPI / LPSS: Add Intel BayTrail ACPI mode PWM")
Fixes: 1bfbd8eb8a7f ("ACPI / LPSS: Add ACPI IDs for Intel Braswell")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Acked-by: Rafael J . Wysocki <rjw@xxxxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
[bwh: Backported to 3.16:
 - Drop changes for Braswell
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -150,6 +150,7 @@ static struct lpss_shared_clock pwm_cloc
 
 static struct lpss_device_desc byt_pwm_dev_desc = {
 	.clk_required = true,
+	.prv_offset = 0x800,
 	.save_ctx = true,
 	.shared_clock = &pwm_clock,
 };