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iwlwifi: pcie: always disable L0S states

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L0S states have been found to be unstable with our devices and in
newer hardware they are not supported at all, so we must always set
the L0S_DISABLED bit.  Previously we were only disabling L0S states if
L1 was supported, because the assumption was that transitions from L0S
to L1 state was the problematic case.  But now we should never use
L0S, so do it regardless of whether L1 is supported or not.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
This commit is contained in:
Luca Coelho 2019-12-10 15:18:16 +02:00
parent 3d1b28fd30
commit cc894b85ab
1 changed files with 5 additions and 10 deletions
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15
drivers/net/wireless/intel/iwlwifi/pcie/trans.c
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@ -302,18 +302,13 @@ void iwl_pcie_apm_config(struct iwl_trans *trans)
u16 cap;
/*
* HW bug W/A for instability in PCIe bus L0S->L1 transition.
* Check if BIOS (or OS) enabled L1-ASPM on this device.
* If so (likely), disable L0S, so device moves directly L0->L1;
* costs negligible amount of power savings.
* If not (unlikely), enable L0S, so there is at least some
* power savings, even without L1.
* L0S states have been found to be unstable with our devices
* and in newer hardware they are not officially supported at
* all, so we must always set the L0S_DISABLED bit.
*/
iwl_set_bit(trans, CSR_GIO_REG, CSR_GIO_REG_VAL_L0S_DISABLED);
pcie_capability_read_word(trans_pcie->pci_dev, PCI_EXP_LNKCTL, &lctl);
if (lctl & PCI_EXP_LNKCTL_ASPM_L1)
iwl_set_bit(trans, CSR_GIO_REG, CSR_GIO_REG_VAL_L0S_DISABLED);
else
iwl_clear_bit(trans, CSR_GIO_REG, CSR_GIO_REG_VAL_L0S_DISABLED);
trans->pm_support = !(lctl & PCI_EXP_LNKCTL_ASPM_L0S);
pcie_capability_read_word(trans_pcie->pci_dev, PCI_EXP_DEVCTL2, &cap);