1d375b58c1
On some devices the contents of the ctrl register get lost over a suspend/resume and the PWM comes back up disabled after the resume. This is seen on some Bay Trail devices with the PWM in ACPI enumerated mode, so it shows up as a platform device instead of a PCI device. If we still think it is enabled and then try to change the duty-cycle after this, we end up with a "PWM_SW_UPDATE was not cleared" error and the PWM is stuck in that state from then on. This commit adds suspend and resume pm callbacks to the pwm-lpss-platform code, which save/restore the ctrl register over a suspend/resume, fixing this. Note that: 1) There is no need to do this over a runtime suspend, since we only runtime suspend when disabled and then we properly set the enable bit and reprogram the timings when we re-enable the PWM. 2) This may be happening on more systems then we realize, but has been covered up sofar by a bug in the acpi-lpss.c code which was save/restoring the regular device registers instead of the lpss private registers due to lpss_device_desc.prv_offset not being set. This is fixed by a later patch in this series. Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
35 lines
859 B
C
35 lines
859 B
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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#ifndef __PWM_LPSS_H
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#define __PWM_LPSS_H
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#include <linux/device.h>
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#include <linux/pwm.h>
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struct pwm_lpss_chip;
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struct pwm_lpss_boardinfo {
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unsigned long clk_rate;
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unsigned int npwm;
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unsigned long base_unit_bits;
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bool bypass;
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};
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struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
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const struct pwm_lpss_boardinfo *info);
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int pwm_lpss_remove(struct pwm_lpss_chip *lpwm);
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int pwm_lpss_suspend(struct device *dev);
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int pwm_lpss_resume(struct device *dev);
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#endif /* __PWM_LPSS_H */
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