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PCI/ASPM: Make sysfs link_state_store() consistent with link_state_show()

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If CONFIG_PCIEASPM_DEBUG is set, then PCI devices have a link_state
attribute.  Reading that attribute shows the state as a bit mask: 1
means L0S upstream, 2 means L0S downstream, and 4 means L1.

Oddly, writing to link_state is inconsistent and gets translated, leading
to mysterious results in which the value you store isn't comparable the
value you load back out.

Fix it by making link_state_store() match link_state_show().

[bhelgaas: Check "aspm_disabled" *before* validating input.  When
"aspm_disabled" is set, this changes the error for invalid input from
-EINVAL to -EPERM.]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Andy Lutomirski 2015-11-19 08:05:35 -08:00 committed by Bjorn Helgaas
parent 1ec218373b
commit 57d86a0485
1 changed files with 5 additions and 11 deletions
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16
drivers/pci/pcie/aspm.c
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@ -834,21 +834,15 @@ static ssize_t link_state_store(struct device *dev,
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pcie_link_state *link, *root = pdev->link_state->root;
u32 val, state = 0;
if (kstrtouint(buf, 10, &val))
return -EINVAL;
u32 state;
if (aspm_disabled)
return -EPERM;
if (n < 1 || val > 3)
return -EINVAL;
/* Convert requested state to ASPM state */
if (val & PCIE_LINK_STATE_L0S)
state |= ASPM_STATE_L0S;
if (val & PCIE_LINK_STATE_L1)
state |= ASPM_STATE_L1;
if (kstrtouint(buf, 10, &state))
return -EINVAL;
if ((state & ~ASPM_STATE_ALL) != 0)
return -EINVAL;
down_read(&pci_bus_sem);
mutex_lock(&aspm_lock);