Re: [PATCH] pci, e1000e: Add and use __pci_disable_link_state

On 05/09/2011 02:35 PM, Jesse Barnes wrote:

On Sun, 08 May 2011 11:54:32 -0700
Yinghai Lu [off-list ref] wrote:

quoted

Need to use it in _e1000e_disable_aspm.
when aer happens,
pci_walk_bus already have down_read(&pci_bus_sem)...
then report_slot_reset
        ==> e1000_io_slot_reset
                ==> e1000e_disable_aspm
                        ==> pci_disable_link_state...

We can not use pci_disable_link_state, and it will try to hold pci_bus_sem again.

Try to have __pci_disable_link_state that will not need to hold pci_bus_sem.

What about the other callers of e1000e_disable_aspm?  Do they already
have the lock held or is it just reset that needs the already locked
version?

yes. 

there is another version when aspm is not defined. and it does not use any lock. 

#ifdef CONFIG_PCIEASPM
static void __e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
{
        pci_disable_link_state(pdev, state);
}
#else
static void __e1000e_disable_aspm(struct pci_dev *pdev, u16 state)
{
        int pos;
        u16 reg16;

        /*
         * Both device and parent should have the same ASPM setting.
         * Disable ASPM in downstream component first and then upstream.
         */
        pos = pci_pcie_cap(pdev);
        pci_read_config_word(pdev, pos + PCI_EXP_LNKCTL, &reg16);
        reg16 &= ~state;
        pci_write_config_word(pdev, pos + PCI_EXP_LNKCTL, reg16);

        if (!pdev->bus->self)
                return;

        pos = pci_pcie_cap(pdev->bus->self);
        pci_read_config_word(pdev->bus->self, pos + PCI_EXP_LNKCTL, &reg16);
        reg16 &= ~state;
        pci_write_config_word(pdev->bus->self, pos + PCI_EXP_LNKCTL, reg16);
}
#endif

quoted

+extern void __pci_disable_link_state(struct pci_dev *pdev, int state);
 extern void pcie_clear_aspm(void);
 extern void pcie_no_aspm(void);
 #else

pci_disable_link_state_locked would be more descriptive and would match
other usage in the kernel.

ok.

Thanks

Yinghai

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