On Wed, May 17, 2023 at 01:52:35PM +0300, Ilpo Järvinen wrote:
Don't assume that only the driver would be accessing LNKCTL. ASPM policy changes can trigger write to LNKCTL outside of driver's control.
Use RMW capability accessors which does proper locking to avoid losing concurrent updates to the register value. On restore, clear the ASPMC field properly.
Fixes: 76d870ed09ab ("ath10k: enable ASPM") Suggested-by: Lukas Wunner lukas@wunner.de Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com Cc: stable@vger.kernel.org
drivers/net/wireless/ath/ath10k/pci.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c index a7f44f6335fb..9275a672f90c 100644 --- a/drivers/net/wireless/ath/ath10k/pci.c +++ b/drivers/net/wireless/ath/ath10k/pci.c @@ -1963,8 +1963,9 @@ static int ath10k_pci_hif_start(struct ath10k *ar) ath10k_pci_irq_enable(ar); ath10k_pci_rx_post(ar);
- pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
ar_pci->link_ctl);
- pcie_capability_clear_and_set_word(ar_pci->pdev, PCI_EXP_LNKCTL,
PCI_EXP_LNKCTL_ASPMC,ar_pci->link_ctl & PCI_EXP_LNKCTL_ASPMC);return 0; } @@ -2821,8 +2822,8 @@ static int ath10k_pci_hif_power_up(struct ath10k *ar, pcie_capability_read_word(ar_pci->pdev, PCI_EXP_LNKCTL, &ar_pci->link_ctl);
- pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
ar_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
- pcie_capability_clear_word(ar_pci->pdev, PCI_EXP_LNKCTL,
PCI_EXP_LNKCTL_ASPMC);
These ath drivers all have the form:
1) read LNKCTL 2) save LNKCTL value in ->link_ctl 3) write LNKCTL with "->link_ctl & ~PCI_EXP_LNKCTL_ASPMC" to disable ASPM 4) write LNKCTL with ->link_ctl, presumably to re-enable ASPM
These patches close the hole between 1) and 3) where other LNKCTL updates could interfere, which is definitely a good thing.
But the hole between 1) and 4) is much bigger and still there. Any update by the PCI core in that interval would be lost.
Straw-man proposal:
- Change pci_disable_link_state() so it ignores aspm_disabled and always disables ASPM even if platform firmware hasn't granted ownership. Maybe this should warn and taint the kernel.
- Change drivers to use pci_disable_link_state() instead of writing LNKCTL directly.
Bjorn