Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com --- This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch. --- drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state; - int error; + int error = 0;
/* * If pci_dev->driver is not set (unbound), we leave the device in D0, @@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
- if (!pm || !pm->runtime_suspend) - return -ENOSYS; - pci_dev->state_saved = false; - error = pm->runtime_suspend(dev); + if (pm && pm->runtime_suspend) + error = pm->runtime_suspend(dev); if (error) { /* * -EBUSY and -EAGAIN is used to request the runtime PM core @@ -1292,7 +1290,7 @@ static int pci_pm_runtime_suspend(struct device *dev)
static int pci_pm_runtime_resume(struct device *dev) { - int rc; + int rc = 0; struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
@@ -1306,14 +1304,12 @@ static int pci_pm_runtime_resume(struct device *dev) if (!pci_dev->driver) return 0;
- if (!pm || !pm->runtime_resume) - return -ENOSYS; - pci_fixup_device(pci_fixup_resume_early, pci_dev); pci_enable_wake(pci_dev, PCI_D0, false); pci_fixup_device(pci_fixup_resume, pci_dev);
- rc = pm->runtime_resume(dev); + if (pm && pm->runtime_resume) + rc = pm->runtime_resume(dev);
pci_dev->runtime_d3cold = false;
On Thu, Oct 18, 2018 at 2:30 PM Jarkko Nikula jarkko.nikula@linux.intel.com wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com
This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch.
Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com
drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state;
int error;
int error = 0; /* * If pci_dev->driver is not set (unbound), we leave the device in D0,@@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
if (!pm || !pm->runtime_suspend)return -ENOSYS;pci_dev->state_saved = false;error = pm->runtime_suspend(dev);
if (pm && pm->runtime_suspend)error = pm->runtime_suspend(dev); if (error) { /* * -EBUSY and -EAGAIN is used to request the runtime PM core@@ -1292,7 +1290,7 @@ static int pci_pm_runtime_suspend(struct device *dev)
static int pci_pm_runtime_resume(struct device *dev) {
int rc;
int rc = 0; struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;@@ -1306,14 +1304,12 @@ static int pci_pm_runtime_resume(struct device *dev) if (!pci_dev->driver) return 0;
if (!pm || !pm->runtime_resume)return -ENOSYS;pci_fixup_device(pci_fixup_resume_early, pci_dev); pci_enable_wake(pci_dev, PCI_D0, false); pci_fixup_device(pci_fixup_resume, pci_dev);rc = pm->runtime_resume(dev);
if (pm && pm->runtime_resume)rc = pm->runtime_resume(dev); pci_dev->runtime_d3cold = false;-- 2.19.1
On Thu, Oct 18, 2018 at 03:30:38PM +0300, Jarkko Nikula wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org
I applied this with Rafael's reviewed-by to pci/misc for v4.20, thanks!
But I dropped the stable tag because if I understand correctly, the point of this is to avoid the need for SIMPLE_DEV_PM_OPS() in drivers that don't need to do anything for PM.
That's worthwhile, but it's not transparently obvious that it would qualify for a stable backport based on this:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documen...
If there's an argument for adding a stable tag, I'll add it , but that justification should be explicit in the changelog.
Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com
This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch.
drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state;
- int error;
- int error = 0;
/* * If pci_dev->driver is not set (unbound), we leave the device in D0, @@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
- if (!pm || !pm->runtime_suspend)
return -ENOSYS;- pci_dev->state_saved = false;
- error = pm->runtime_suspend(dev);
- if (pm && pm->runtime_suspend)
error = pm->runtime_suspend(dev);
- -EBUSY and -EAGAIN is used to request the runtime PM core
@@ -1292,7 +1290,7 @@ static int pci_pm_runtime_suspend(struct device *dev) static int pci_pm_runtime_resume(struct device *dev) {
- int rc;
- int rc = 0; struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
@@ -1306,14 +1304,12 @@ static int pci_pm_runtime_resume(struct device *dev) if (!pci_dev->driver) return 0;
- if (!pm || !pm->runtime_resume)
return -ENOSYS;- pci_fixup_device(pci_fixup_resume_early, pci_dev); pci_enable_wake(pci_dev, PCI_D0, false); pci_fixup_device(pci_fixup_resume, pci_dev);
- rc = pm->runtime_resume(dev);
- if (pm && pm->runtime_resume)
rc = pm->runtime_resume(dev);pci_dev->runtime_d3cold = false; -- 2.19.1
On 10/19/2018 12:25 AM, Bjorn Helgaas wrote:
On Thu, Oct 18, 2018 at 03:30:38PM +0300, Jarkko Nikula wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org
I applied this with Rafael's reviewed-by to pci/misc for v4.20, thanks!
But I dropped the stable tag because if I understand correctly, the point of this is to avoid the need for SIMPLE_DEV_PM_OPS() in drivers that don't need to do anything for PM.
That's worthwhile, but it's not transparently obvious that it would qualify for a stable backport based on this:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documen...
If there's an argument for adding a stable tag, I'll add it , but that justification should be explicit in the changelog.
No disagreement here. I was thinking a second or two before sending the patch may I Cc or not the stable. I went adding it since this actually fixes a PM regression on i2c-i801 after v4.18. SMBus PCI device doesn't go to D3 and /sys/bus/pci/devices/[0000:00:1f.3 etc]/power/runtime_status shows "error" when runtime PM framework attempts to autosuspend the device.
But given that most of the platforms I have seen don't implement the PM capabilities for SMBus PCI device, a few do implement though, and we haven't got any regression reports either so this is not very fatal IMHO.
I definitely don't want to see massive regression from different PCI systems either. Queueing for v4.20 sounds reasonable and we can ask to cherry-pick the commit into v4.18 and v4.19 stable kernels if nothing fatal shows up.
Hi Jarkko,
On Thu, 18 Oct 2018 15:30:38 +0300, Jarkko Nikula wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Thank you very much for looking into this and providing a fix.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com
This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch.
drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state;
- int error;
- int error = 0;
/* * If pci_dev->driver is not set (unbound), we leave the device in D0, @@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
- if (!pm || !pm->runtime_suspend)
return -ENOSYS;- pci_dev->state_saved = false;
- error = pm->runtime_suspend(dev);
- if (pm && pm->runtime_suspend)
error = pm->runtime_suspend(dev);
- -EBUSY and -EAGAIN is used to request the runtime PM core
Later in this function, pm is dereferenced again. It happens twice in the "if (error)" condition where it is currently safe (error can't be non-zero if pm->runtime_suspend() has not been called, and obviously pm->runtime_suspend() can't have been called if pm was NULL). However it also happens later without the condition:
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0 && pci_dev->current_state != PCI_UNKNOWN) { WARN_ONCE(pci_dev->current_state != prev, "PCI PM: State of device not saved by %pF\n", pm->runtime_suspend); return 0; }
I am no expert of the PM framework but is there no risk to dereference NULL at this point? Or even if pm is non-NULL, pm->runtime_suspend may be NULL, leading to a confusing warning message?
More generally, I would feel better if instead of initializing error to 0, we would move under the "if (pm && pm->runtime_suspend)" condition everything that must not be run if pm->runtime_suspend is not defined. That would make the possible code flows a lot clearer.
@@ -1292,7 +1290,7 @@ static int pci_pm_runtime_suspend(struct device *dev) static int pci_pm_runtime_resume(struct device *dev) {
- int rc;
- int rc = 0; struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
@@ -1306,14 +1304,12 @@ static int pci_pm_runtime_resume(struct device *dev) if (!pci_dev->driver) return 0;
- if (!pm || !pm->runtime_resume)
return -ENOSYS;- pci_fixup_device(pci_fixup_resume_early, pci_dev); pci_enable_wake(pci_dev, PCI_D0, false); pci_fixup_device(pci_fixup_resume, pci_dev);
- rc = pm->runtime_resume(dev);
- if (pm && pm->runtime_resume)
rc = pm->runtime_resume(dev);pci_dev->runtime_d3cold = false;
The rest looks good to me.
Thanks,
On Fri, Oct 19, 2018 at 03:21:05PM +0200, Jean Delvare wrote:
On Thu, 18 Oct 2018 15:30:38 +0300, Jarkko Nikula wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Thank you very much for looking into this and providing a fix.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com
This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch.
drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state;
- int error;
- int error = 0;
/* * If pci_dev->driver is not set (unbound), we leave the device in D0, @@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
- if (!pm || !pm->runtime_suspend)
return -ENOSYS;- pci_dev->state_saved = false;
- error = pm->runtime_suspend(dev);
- if (pm && pm->runtime_suspend)
error = pm->runtime_suspend(dev);
- -EBUSY and -EAGAIN is used to request the runtime PM core
Later in this function, pm is dereferenced again. It happens twice in the "if (error)" condition where it is currently safe (error can't be non-zero if pm->runtime_suspend() has not been called, and obviously pm->runtime_suspend() can't have been called if pm was NULL). However it also happens later without the condition:
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0 && pci_dev->current_state != PCI_UNKNOWN) { WARN_ONCE(pci_dev->current_state != prev, "PCI PM: State of device not saved by %pF\n", pm->runtime_suspend); return 0; }
I am no expert of the PM framework but is there no risk to dereference NULL at this point? Or even if pm is non-NULL, pm->runtime_suspend may be NULL, leading to a confusing warning message?
More generally, I would feel better if instead of initializing error to 0, we would move under the "if (pm && pm->runtime_suspend)" condition everything that must not be run if pm->runtime_suspend is not defined. That would make the possible code flows a lot clearer.
I agree, this isn't good. Even if it's safe (and I don't think that second spot is safe), it's too hard to analyze. I'm going to drop this for now.
Jarkko, I assume a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM"), which you reference as "Fixes:" is what causes the regression. If you can update the changelog so it mentions the regression, why it happens, and why this patch fixes it, we'll be in a better spot to backport it to stable kernels.
Bjorn
On 10/20/2018 07:19 PM, Bjorn Helgaas wrote:
On Fri, Oct 19, 2018 at 03:21:05PM +0200, Jean Delvare wrote:
Later in this function, pm is dereferenced again. It happens twice in the "if (error)" condition where it is currently safe (error can't be non-zero if pm->runtime_suspend() has not been called, and obviously pm->runtime_suspend() can't have been called if pm was NULL). However it also happens later without the condition:
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0 && pci_dev->current_state != PCI_UNKNOWN) { WARN_ONCE(pci_dev->current_state != prev, "PCI PM: State of device not saved by %pF\n", pm->runtime_suspend); return 0; }
I am no expert of the PM framework but is there no risk to dereference NULL at this point? Or even if pm is non-NULL, pm->runtime_suspend may be NULL, leading to a confusing warning message?
Thanks for spotting this! I don't have any excuse why I was so completely blind.
More generally, I would feel better if instead of initializing error to 0, we would move under the "if (pm && pm->runtime_suspend)" condition everything that must not be run if pm->runtime_suspend is not defined. That would make the possible code flows a lot clearer.
I agree, this isn't good. Even if it's safe (and I don't think that second spot is safe), it's too hard to analyze. I'm going to drop this for now.
Thanks. I'll cook a better version.
On Sat, Oct 20, 2018 at 6:19 PM Bjorn Helgaas helgaas@kernel.org wrote:
On Fri, Oct 19, 2018 at 03:21:05PM +0200, Jean Delvare wrote:
On Thu, 18 Oct 2018 15:30:38 +0300, Jarkko Nikula wrote:
Allow PCI core to do runtime PM to devices without needing to use dummy runtime PM callback functions if there is no need to do anything device specific beyond PCI device power state management.
Implement this by letting core to change device power state during runtime PM transitions even if no callback functions are defined.
Thank you very much for looking into this and providing a fix.
Fixes: a9c8088c7988 ("i2c: i801: Don't restore config registers on runtime PM") Reported-by: Mika Westerberg mika.westerberg@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Jarkko Nikula jarkko.nikula@linux.intel.com
This is related to my i2c-i801.c fix thread back in June which I completely forgot till now: https://lkml.org/lkml/2018/6/27/642 Discussion back then was that it should be handled in the PCI PM instead of having dummy functions in the drivers. I wanted to respin with a patch.
drivers/pci/pci-driver.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index bef17c3fca67..6185b878ede1 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1239,7 +1239,7 @@ static int pci_pm_runtime_suspend(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; pci_power_t prev = pci_dev->current_state;
- int error;
int error = 0;
/*
- If pci_dev->driver is not set (unbound), we leave the device in D0,
@@ -1251,11 +1251,9 @@ static int pci_pm_runtime_suspend(struct device *dev) return 0; }
- if (!pm || !pm->runtime_suspend)
return -ENOSYS;- pci_dev->state_saved = false;
- error = pm->runtime_suspend(dev);
- if (pm && pm->runtime_suspend)
error = pm->runtime_suspend(dev);Later in this function, pm is dereferenced again. It happens twice in the "if (error)" condition where it is currently safe (error can't be non-zero if pm->runtime_suspend() has not been called, and obviously pm->runtime_suspend() can't have been called if pm was NULL). However it also happens later without the condition:
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0 && pci_dev->current_state != PCI_UNKNOWN) { WARN_ONCE(pci_dev->current_state != prev, "PCI PM: State of device not saved by %pF\n", pm->runtime_suspend); return 0; }I am no expert of the PM framework but is there no risk to dereference NULL at this point? Or even if pm is non-NULL, pm->runtime_suspend may be NULL, leading to a confusing warning message?
More generally, I would feel better if instead of initializing error to 0, we would move under the "if (pm && pm->runtime_suspend)" condition everything that must not be run if pm->runtime_suspend is not defined. That would make the possible code flows a lot clearer.
I agree, this isn't good. Even if it's safe (and I don't think that second spot is safe), it's too hard to analyze. I'm going to drop this for now.
Yeah, sorry for missing this.
[Note to self: be more careful with patch reviews in the future.]
Cheers, Rafael
linux-stable-mirror@lists.linaro.org
-
Bjorn Helgaas -
Jarkko Nikula -
Jean Delvare -
Rafael J. Wysocki