cd543e686c
* Tue May 19 2020 CKI@GitLab <cki-project@redhat.com> [5.7.0-0.rc6.20200519git642b151f45dd.1]
- 642b151f45dd rebase
- pwm: lpss: Fix get_state runtime-pm reference handling (Hans de Goede)
- Updated changelog for the release based on v5.7-rc6 ("CKI@GitLab")
Resolves: rhbz#
Signed-off-by: Justin M. Forbes <jforbes@fedoraproject.org>
101 lines
3.6 KiB
Diff
101 lines
3.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Tue, 12 May 2020 00:39:24 +0200
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Subject: [PATCH] pwm: lpss: Fix get_state runtime-pm reference handling
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Before commit cfc4c189bc70 ("pwm: Read initial hardware state at request
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time"), a driver's get_state callback would get called once per PWM from
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pwmchip_add().
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pwm-lpss' runtime-pm code was relying on this, getting a runtime-pm ref for
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PWMs which are enabled at probe time from within its get_state callback,
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before enabling runtime-pm.
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The change to calling get_state at request time causes a number of
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problems:
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1. PWMs enabled at probe time may get runtime suspended before they are
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requested, causing e.g. a LCD backlight controlled by the PWM to turn off.
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2. When the request happens when the PWM has been runtime suspended, the
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ctrl register will read all 1 / 0xffffffff, causing get_state to store
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bogus values in the pwm_state.
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3. get_state was using an async pm_runtime_get() call, because it assumed
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that runtime-pm has not been enabled yet. If shortly after the request an
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apply call is made, then the pwm_lpss_is_updating() check may trigger
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because the resume triggered by the pm_runtime_get() call is not complete
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yet, so the ctrl register still reads all 1 / 0xffffffff.
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This commit fixes these issues by moving the initial pm_runtime_get() call
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for PWMs which are enabled at probe time to the pwm_lpss_probe() function;
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and by making get_state take a runtime-pm ref before reading the ctrl reg.
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BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1828927
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Fixes: cfc4c189bc70 ("pwm: Read initial hardware state at request time")
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Cc: stable@vger.kernel.org
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Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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Upstream Status: https://lore.kernel.org/linux-acpi/5f15f6bc-8650-d86e-893f-0d41557c57c7@redhat.com/
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---
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drivers/pwm/pwm-lpss.c | 15 +++++++++++----
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1 file changed, 11 insertions(+), 4 deletions(-)
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diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
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index 75bbfe5f3bc2..9d965ffe66d1 100644
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--- a/drivers/pwm/pwm-lpss.c
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+++ b/drivers/pwm/pwm-lpss.c
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@@ -158,7 +158,6 @@ static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
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return 0;
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}
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-/* This function gets called once from pwmchip_add to get the initial state */
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static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state)
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{
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@@ -167,6 +166,8 @@ static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
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unsigned long long base_unit, freq, on_time_div;
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u32 ctrl;
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+ pm_runtime_get_sync(chip->dev);
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+
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base_unit_range = BIT(lpwm->info->base_unit_bits);
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ctrl = pwm_lpss_read(pwm);
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@@ -187,8 +188,7 @@ static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
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state->polarity = PWM_POLARITY_NORMAL;
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state->enabled = !!(ctrl & PWM_ENABLE);
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- if (state->enabled)
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- pm_runtime_get(chip->dev);
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+ pm_runtime_put(chip->dev);
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}
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static const struct pwm_ops pwm_lpss_ops = {
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@@ -202,7 +202,8 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
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{
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struct pwm_lpss_chip *lpwm;
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unsigned long c;
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- int ret;
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+ int i, ret;
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+ u32 ctrl;
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if (WARN_ON(info->npwm > MAX_PWMS))
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return ERR_PTR(-ENODEV);
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@@ -232,6 +233,12 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
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return ERR_PTR(ret);
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}
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+ for (i = 0; i < lpwm->info->npwm; i++) {
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+ ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]);
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+ if (ctrl & PWM_ENABLE)
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+ pm_runtime_get(dev);
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+ }
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+
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return lpwm;
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}
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EXPORT_SYMBOL_GPL(pwm_lpss_probe);
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--
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2.26.2
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