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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> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
/*
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* Intel Low Power Subsystem PWM controller driver
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*
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* Copyright (C) 2014, Intel Corporation
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*
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* Derived from the original pwm-lpss.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/acpi.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/pm_runtime.h>
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#include "pwm-lpss.h"
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/* BayTrail */
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static const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
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.clk_rate = 25000000,
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.npwm = 1,
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.base_unit_bits = 16,
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};
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/* Braswell */
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static const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
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.clk_rate = 19200000,
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.npwm = 1,
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.base_unit_bits = 16,
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.other_devices_aml_touches_pwm_regs = true,
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};
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/* Broxton */
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static const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
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.clk_rate = 19200000,
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.npwm = 4,
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.base_unit_bits = 22,
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.bypass = true,
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};
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static int pwm_lpss_probe_platform(struct platform_device *pdev)
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{
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const struct pwm_lpss_boardinfo *info;
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const struct acpi_device_id *id;
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struct pwm_lpss_chip *lpwm;
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struct resource *r;
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id = acpi_match_device(pdev->dev.driver->acpi_match_table, &pdev->dev);
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if (!id)
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return -ENODEV;
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info = (const struct pwm_lpss_boardinfo *)id->driver_data;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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lpwm = pwm_lpss_probe(&pdev->dev, r, info);
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if (IS_ERR(lpwm))
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return PTR_ERR(lpwm);
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platform_set_drvdata(pdev, lpwm);
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dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_SMART_PREPARE);
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pm_runtime_set_active(&pdev->dev);
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pm_runtime_enable(&pdev->dev);
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return 0;
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}
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static int pwm_lpss_remove_platform(struct platform_device *pdev)
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{
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struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
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pm_runtime_disable(&pdev->dev);
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return pwm_lpss_remove(lpwm);
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}
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static int pwm_lpss_prepare(struct device *dev)
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{
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struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
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/*
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* If other device's AML code touches the PWM regs on suspend/resume
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* force runtime-resume the PWM controller to allow this.
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*/
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if (lpwm->info->other_devices_aml_touches_pwm_regs)
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return 0; /* Force runtime-resume */
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return 1; /* If runtime-suspended leave as is */
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}
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static const struct dev_pm_ops pwm_lpss_platform_pm_ops = {
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.prepare = pwm_lpss_prepare,
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SET_SYSTEM_SLEEP_PM_OPS(pwm_lpss_suspend, pwm_lpss_resume)
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};
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static const struct acpi_device_id pwm_lpss_acpi_match[] = {
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{ "80860F09", (unsigned long)&pwm_lpss_byt_info },
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{ "80862288", (unsigned long)&pwm_lpss_bsw_info },
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{ "80862289", (unsigned long)&pwm_lpss_bsw_info },
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{ "80865AC8", (unsigned long)&pwm_lpss_bxt_info },
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{ },
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};
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MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
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static struct platform_driver pwm_lpss_driver_platform = {
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.driver = {
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.name = "pwm-lpss",
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.acpi_match_table = pwm_lpss_acpi_match,
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.pm = &pwm_lpss_platform_pm_ops,
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},
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.probe = pwm_lpss_probe_platform,
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.remove = pwm_lpss_remove_platform,
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};
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module_platform_driver(pwm_lpss_driver_platform);
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MODULE_DESCRIPTION("PWM platform driver for Intel LPSS");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:pwm-lpss");
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