Messages in this thread | | | Subject | Re: [PATCH] PCI: Save/restore L1 PM Substate extended capability registers | From | Vidya Sagar <> | Date | Wed, 9 Dec 2020 09:38:00 +0530 |
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There is a change already available for it in linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=4257f7e008ea394fcecc050f1569c3503b8bcc15
Thanks, Vidya Sagar
On 12/9/2020 3:36 AM, David E. Box wrote: > External email: Use caution opening links or attachments > > > On Intel systems that support ACPI Low Power Idle it has been observed > that the L1 Substate capability can return disabled after a s2idle > cycle. This causes the loss of L1 Substate support during runtime > leading to higher power consumption. Add save/restore of the L1SS > control registers. > > Signed-off-by: David E. Box <david.e.box@linux.intel.com> > --- > drivers/pci/pci.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 49 insertions(+) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index e578d34095e9..beee3d9952a6 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -1539,6 +1539,48 @@ static void pci_restore_ltr_state(struct pci_dev *dev) > pci_write_config_word(dev, ltr + PCI_LTR_MAX_NOSNOOP_LAT, *cap++); > } > > +static void pci_save_l1ss_state(struct pci_dev *dev) > +{ > + int l1ss; > + struct pci_cap_saved_state *save_state; > + u16 *cap; > + > + if (!pci_is_pcie(dev)) > + return; > + > + l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS); > + if (!l1ss) > + return; > + > + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS); > + if (!save_state) { > + pci_err(dev, "no suspend buffer for L1 Substates\n"); > + return; > + } > + > + cap = (u16 *)&save_state->cap.data[0]; > + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL1, cap++); > + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL1 + 2, cap++); > + pci_read_config_word(dev, l1ss + PCI_L1SS_CTL2, cap++); > +} > + > +static void pci_restore_l1ss_state(struct pci_dev *dev) > +{ > + struct pci_cap_saved_state *save_state; > + int l1ss; > + u16 *cap; > + > + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS); > + l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS); > + if (!save_state || !l1ss) > + return; > + > + cap = (u16 *)&save_state->cap.data[0]; > + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL1, *cap++); > + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL1 + 2, *cap++); > + pci_write_config_word(dev, l1ss + PCI_L1SS_CTL2, *cap++); > +} > + > /** > * pci_save_state - save the PCI configuration space of a device before > * suspending > @@ -1563,6 +1605,7 @@ int pci_save_state(struct pci_dev *dev) > if (i != 0) > return i; > > + pci_save_l1ss_state(dev); > pci_save_ltr_state(dev); > pci_save_dpc_state(dev); > pci_save_aer_state(dev); > @@ -1670,6 +1713,7 @@ void pci_restore_state(struct pci_dev *dev) > */ > pci_restore_ltr_state(dev); > > + pci_restore_l1ss_state(dev); > pci_restore_pcie_state(dev); > pci_restore_pasid_state(dev); > pci_restore_pri_state(dev); > @@ -3332,6 +3376,11 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev) > if (error) > pci_err(dev, "unable to allocate suspend buffer for LTR\n"); > > + error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_L1SS, > + 3 * sizeof(u16)); > + if (error) > + pci_err(dev, "unable to allocate suspend buffer for L1 Substates\n"); > + > pci_allocate_vc_save_buffers(dev); > } > > -- > 2.20.1 >
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