Re: [PATCH v2 3/3] PCI/ASPM: add sysfs attributes for controlling ASPM

Heiner Kallweit
2019-08-22T19:15:43Z

On 22.08.2019 15:05, Greg KH wrote:
> On Wed, Aug 21, 2019 at 08:18:41PM +0200, Heiner Kallweit wrote:
>> Background of this extension is a problem with the r8169 network driver.
>> Several combinations of board chipsets and network chip versions have
>> problems if ASPM is enabled, therefore we have to disable ASPM per default.
>> However especially on notebooks ASPM can provide significant power-saving,
>> therefore we want to give users the option to enable ASPM. With the new sysfs
>> attributes users can control which ASPM link-states are enabled/disabled.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> v2:
>> - use a dedicated sysfs attribute per link state
>> - allow separate control of ASPM and PCI PM L1 sub-states
>> ---
>> Documentation/ABI/testing/sysfs-bus-pci | 13 ++
>> drivers/pci/pci.h | 8 +-
>> drivers/pci/pcie/aspm.c | 263 +++++++++++++++++++++++-
>> 3 files changed, 276 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
>> index 8bfee557e..38b565c30 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-pci
>> +++ b/Documentation/ABI/testing/sysfs-bus-pci
>> @@ -347,3 +347,16 @@ Description:
>> If the device has any Peer-to-Peer memory registered, this
>> file contains a '1' if the memory has been published for
>> use outside the driver that owns the device.
>> +
>> +What /sys/bus/pci/devices/.../power/aspm_l0s
>> +What /sys/bus/pci/devices/.../power/aspm_l1
>> +What /sys/bus/pci/devices/.../power/aspm_l1_1
>> +What /sys/bus/pci/devices/.../power/aspm_l1_2
>> +What /sys/bus/pci/devices/.../power/aspm_l1_1_pcipm
>> +What /sys/bus/pci/devices/.../power/aspm_l1_2_pcipm
>> +What /sys/bus/pci/devices/.../power/aspm_clkpm
>
> Wait, there already is a "power" subdirectory for all devices in the
> system, are you adding another one, or files to that already-created
> directory?
>
This is the standard "power" directory dynamically created by
dpm_sysfs_add().

>> +date: August 2019
>> +Contact: Heiner Kallweit <hkallweit1@gmail.com>
>> +Description: If ASPM is supported for an endpoint, then these files
>> + can be used to disable or enable the individual
>> + power management states.
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index 3f126f808..e51c91f38 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -525,17 +525,13 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev);
>> void pcie_aspm_exit_link_state(struct pci_dev *pdev);
>> void pcie_aspm_pm_state_change(struct pci_dev *pdev);
>> void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
>> +void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
>> +void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
>> #else
>> static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
>> static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
>> static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
>> static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
>> -#endif
>> -
>> -#ifdef CONFIG_PCIEASPM_DEBUG
>> -void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
>> -void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
>> -#else
>> static inline void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev) { }
>> static inline void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev) { }
>> #endif
>> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
>> index 149b876c9..e7dfcd1bd 100644
>> --- a/drivers/pci/pcie/aspm.c
>> +++ b/drivers/pci/pcie/aspm.c
>> @@ -1275,38 +1275,297 @@ static ssize_t clk_ctl_store(struct device *dev,
>>
>> static DEVICE_ATTR_RW(link_state);
>> static DEVICE_ATTR_RW(clk_ctl);
>> +#endif
>> +
>> +static const char power_group[] = "power";
>> +
>> +static struct pcie_link_state *aspm_get_parent_link(struct pci_dev *pdev)
>> +{
>> + struct pci_dev *parent = pdev->bus->self;
>> +
>> + if (pdev->has_secondary_link)
>> + parent = pdev;
>> +
>> + return parent ? parent->link_state : NULL;
>> +}
>> +
>> +static bool pcie_check_valid_aspm_endpoint(struct pci_dev *pdev)
>> +{
>> + struct pcie_link_state *link;
>> +
>> + if (pci_pcie_type(pdev) != PCI_EXP_TYPE_ENDPOINT)
>> + return false;
>> +
>> + link = aspm_get_parent_link(pdev);
>> +
>> + return link && link->aspm_capable;
>> +}
>> +
>> +static ssize_t aspm_attr_show_common(struct device *dev,
>> + struct device_attribute *attr,
>> + char *buf, int state)
>> +{
>> + struct pci_dev *pdev = to_pci_dev(dev);
>> + struct pcie_link_state *link;
>> + int val;
>> +
>> + link = aspm_get_parent_link(pdev);
>> + if (!link)
>> + return -EOPNOTSUPP;
>> +
>> + mutex_lock(&aspm_lock);
>> + val = !!(link->aspm_enabled & state);
>> + mutex_unlock(&aspm_lock);
>> +
>> + return snprintf(buf, PAGE_SIZE, "%d\n", val);
>
> For sysfs files, you never need to use snprintf() as you "know" the size
> of the buffer is big, and you are just printing out a single number. So
> that can be cleaned up in all of these attribute files.
>
>> +}
>> +
>> +static ssize_t aspm_l0s_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L0S);
>> +}
>> +
>> +static ssize_t aspm_l1_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L1);
>> +}
>> +
>> +static ssize_t aspm_l1_1_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L1_1);
>> +}
>> +
>> +static ssize_t aspm_l1_2_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L1_2);
>> +}
>> +
>> +static ssize_t aspm_l1_1_pcipm_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L1_1_PCIPM);
>> +}
>> +
>> +static ssize_t aspm_l1_2_pcipm_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_L1_2_PCIPM);
>> +}
>> +
>> +static ssize_t aspm_attr_store_common(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len, int state)
>> +{
>> + struct pci_dev *pdev = to_pci_dev(dev);
>> + struct pcie_link_state *link;
>> + bool state_enable;
>> +
>> + if (aspm_disabled)
>> + return -EPERM;
>> +
>> + link = aspm_get_parent_link(pdev);
>> + if (!link)
>> + return -EOPNOTSUPP;
>> +
>> + if (!(link->aspm_capable & state))
>> + return -EOPNOTSUPP;
>> +
>> + if (strtobool(buf, &state_enable) < 0)
>> + return -EINVAL;
>> +
>> + down_read(&pci_bus_sem);
>> + mutex_lock(&aspm_lock);
>> +
>> + if (state_enable)
>> + link->aspm_disable &= ~state;
>> + else
>> + link->aspm_disable |= state;
>> +
>> + if (link->aspm_disable & ASPM_STATE_L1)
>> + link->aspm_disable |= ASPM_STATE_L1SS;
>> +
>> + pcie_config_aspm_link(link, policy_to_aspm_state(link));
>
> This function can't fail?
>
It has no return value.

>> +
>> + mutex_unlock(&aspm_lock);
>> + up_read(&pci_bus_sem);
>> +
>> + return len;
>> +}
>> +
>> +static ssize_t aspm_l0s_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_L0S);
>> +}
>> +
>> +static ssize_t aspm_l1_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_L1);
>> +}
>> +
>> +static ssize_t aspm_l1_1_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_L1_1);
>> +}
>> +
>> +static ssize_t aspm_l1_2_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_L1_2);
>> +}
>> +
>> +static ssize_t aspm_l1_1_pcipm_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len,
>> + ASPM_STATE_L1_1_PCIPM);
>> +}
>> +
>> +static ssize_t aspm_l1_2_pcipm_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + return aspm_attr_store_common(dev, attr, buf, len,
>> + ASPM_STATE_L1_2_PCIPM);
>> +}
>> +
>> +static ssize_t aspm_clkpm_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct pci_dev *pdev = to_pci_dev(dev);
>> + struct pcie_link_state *link;
>> + int val;
>> +
>> + link = aspm_get_parent_link(pdev);
>> + if (!link)
>> + return -EOPNOTSUPP;
>> +
>> + mutex_lock(&aspm_lock);
>> + val = link->clkpm_enabled;
>> + mutex_unlock(&aspm_lock);
>> +
>> + return snprintf(buf, PAGE_SIZE, "%d\n", val);
>> +}
>> +
>> +static ssize_t aspm_clkpm_store(struct device *dev,
>> + struct device_attribute *attr,
>> + const char *buf, size_t len)
>> +{
>> + struct pci_dev *pdev = to_pci_dev(dev);
>> + struct pcie_link_state *link;
>> + bool state_enable;
>> +
>> + if (aspm_disabled)
>> + return -EPERM;
>> +
>> + link = aspm_get_parent_link(pdev);
>> + if (!link)
>> + return -EOPNOTSUPP;
>> +
>> + if (!link->clkpm_capable)
>> + return -EOPNOTSUPP;
>> +
>> + if (strtobool(buf, &state_enable) < 0)
>> + return -EINVAL;
>> +
>> + down_read(&pci_bus_sem);
>> + mutex_lock(&aspm_lock);
>> +
>> + link->clkpm_disable = !state_enable;
>> + pcie_set_clkpm(link, policy_to_clkpm_state(link));
>> +
>> + mutex_unlock(&aspm_lock);
>> + up_read(&pci_bus_sem);
>> +
>> + return len;
>> +}
>> +
>> +static DEVICE_ATTR_RW(aspm_l0s);
>> +static DEVICE_ATTR_RW(aspm_l1);
>> +static DEVICE_ATTR_RW(aspm_l1_1);
>> +static DEVICE_ATTR_RW(aspm_l1_2);
>> +static DEVICE_ATTR_RW(aspm_l1_1_pcipm);
>> +static DEVICE_ATTR_RW(aspm_l1_2_pcipm);
>> +static DEVICE_ATTR_RW(aspm_clkpm);
>>
>> -static char power_group[] = "power";
>> void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev)
>> {
>> struct pcie_link_state *link_state = pdev->link_state;
>>
>> + if (pcie_check_valid_aspm_endpoint(pdev)) {
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l0s.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_1.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_2.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_1_pcipm.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_2_pcipm.attr, power_group);
>> + sysfs_add_file_to_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_clkpm.attr, power_group);
>
> Huh? First of, if you are ever in a driver, and you have to call a
> sysfs_* function, you know something is wrong.
>
> Why are you dynamically adding files to a group? These should all be
> statically allocated and then at creation time you can dynamically
> determine if you need to show them or not. Use the is_visable callback
> for that.
>

The "power" group is dynamically created by the base driver core
(dpm_sysfs_add). Not sure how the ASPM sysfs files could be statically
allocated. We could add an attribute group to the "pci" bus_type,
but this doesn't feel right.
What we could do to make it simpler:
Create an attribute group and then use sysfs_merge_group().
But I see no way not to use sysfs_xxx functions. Also functions
like device_add_groups() are just very simple wrappers around sysfs_
functions.

Alternatively we could not use the existing "power" group but create
our own group with device_add_group(). But I don't see that we gain much.

>> + }
>> +
>> if (!link_state)
>> return;
>>
>> +#ifdef CONFIG_PCIEASPM_DEBUG
>> if (link_state->aspm_support)
>> sysfs_add_file_to_group(&pdev->dev.kobj,
>> &dev_attr_link_state.attr, power_group);
>> if (link_state->clkpm_capable)
>> sysfs_add_file_to_group(&pdev->dev.kobj,
>> &dev_attr_clk_ctl.attr, power_group);
>
> Same here.
>
>> +#endif
>> }
>>
>> void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
>> {
>> struct pcie_link_state *link_state = pdev->link_state;
>>
>> + if (pcie_check_valid_aspm_endpoint(pdev)) {
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l0s.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_1.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_2.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_1_pcipm.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_l1_2_pcipm.attr, power_group);
>> + sysfs_remove_file_from_group(&pdev->dev.kobj,
>> + &dev_attr_aspm_clkpm.attr, power_group);
>
> And then you never have to do this type of messy logic at all.
>
> Ick.
>
>> + }
>> +
>> if (!link_state)
>> return;
>>
>> +#ifdef CONFIG_PCIEASPM_DEBUG
>> if (link_state->aspm_support)
>> sysfs_remove_file_from_group(&pdev->dev.kobj,
>> &dev_attr_link_state.attr, power_group);
>> if (link_state->clkpm_capable)
>> sysfs_remove_file_from_group(&pdev->dev.kobj,
>> &dev_attr_clk_ctl.attr, power_group);
>
> And you get to drop this nonsense as well.
>
Right, with the new attributes CONFIG_PCIEASPM_DEBUG and all
related stuff could be removed most likely.

> thanks,
>
> greg k-h
>

Heiner