Re: [PATCH v2 1/2] PCI: PCIe: ASPM: Introduce pcie_aspm_enabled_mask()

[Bjorn Helgaas]

On Thu, Aug 08, 2019 at 12:06:52PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> Add a function returning the mask of currently enabled ASPM link
> states for a given device.
> 
> It will be used by the NVMe driver to decide how to handle the
> device during system suspend.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> 
> -> v2:
>   * Move the PCI/PCIe ASPM changes to a separate patch.
>   * Add the _mask suffix to the new function name.
>   * Add EXPORT_SYMBOL_GPL() to the new function.
>   * Avoid adding an unnecessary blank line.
> 
> ---
>  drivers/pci/pcie/aspm.c |   20 ++++++++++++++++++++
>  include/linux/pci.h     |    3 +++
>  2 files changed, 23 insertions(+)
> 
> Index: linux-pm/drivers/pci/pcie/aspm.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pcie/aspm.c
> +++ linux-pm/drivers/pci/pcie/aspm.c
> @@ -1170,6 +1170,26 @@ static int pcie_aspm_get_policy(char *bu
>  module_param_call(policy, pcie_aspm_set_policy, pcie_aspm_get_policy,
>  	NULL, 0644);
>  
> +/*
> + * pcie_aspm_enabled_mask - Return the mask of enabled ASPM link states.
> + * @pci_device: Target device.
> + */
> +u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device)
> +{
> +	struct pci_dev *bridge = pci_upstream_bridge(pci_device);
> +	u32 ret;
> +
> +	if (!bridge)
> +		return 0;
> +
> +	mutex_lock(&aspm_lock);
> +	ret = bridge->link_state ? bridge->link_state->aspm_enabled : 0;

This returns the "aspm_enabled" mask, but the values of that mask are
combinations of:

  ASPM_STATE_L0S_UP
  ASPM_STATE_L0S_DW
  ASPM_STATE_L1
  ...

which are defined internally in drivers/pci/pcie/aspm.c and not
visible to the caller of pcie_aspm_enabled_mask().  If there's no need
for the actual mask (the current caller doesn't seem to use it), maybe
this could be a boolean?

> +	mutex_unlock(&aspm_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(pcie_aspm_enabled_mask);
> +
>  #ifdef CONFIG_PCIEASPM_DEBUG
>  static ssize_t link_state_show(struct device *dev,
>  		struct device_attribute *attr,
> Index: linux-pm/include/linux/pci.h
> ===================================================================
> --- linux-pm.orig/include/linux/pci.h
> +++ linux-pm/include/linux/pci.h
> @@ -1567,8 +1567,11 @@ extern bool pcie_ports_native;
>  
>  #ifdef CONFIG_PCIEASPM
>  bool pcie_aspm_support_enabled(void);
> +u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device);
>  #else
>  static inline bool pcie_aspm_support_enabled(void) { return false; }
> +static inline u32 pcie_aspm_enabled_mask(struct pci_dev *pci_device)
> +{ return 0; }
>  #endif
>  
>  #ifdef CONFIG_PCIEAER
> 
> 
>