On Tue, 2024-04-30 at 15:46 +0800, Jian-Hong Pan wrote: > David E. Box <david.e.box@xxxxxxxxxxxxxxx> 於 2024年4月27日 週六 上午8:03寫道： > > > > Hi Jian-Hong, > > > > On Wed, 2024-04-24 at 19:02 +0800, Jian-Hong Pan wrote: > > > Currently, when enable link's L1.2 features with > > > __pci_enable_link_state(), > > > it configs the link directly without ensuring related L1.2 parameters, > > > such > > > as T_POWER_ON, Common_Mode_Restore_Time, and LTR_L1.2_THRESHOLD have been > > > programmed. > > > > > > This leads the link's L1.2 between PCIe Root Port and child device gets > > > wrong configs when a caller tries to enabled it. > > > > > > Here is a failed example on ASUS B1400CEAE with enabled VMD: > > > > > > 10000:e0:06.0 PCI bridge: Intel Corporation 11th Gen Core Processor PCIe > > > Controller (rev 01) (prog-if 00 [Normal decode]) > > > ... > > > Capabilities: [200 v1] L1 PM Substates > > > L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ > > > L1_PM_Substates+ > > > PortCommonModeRestoreTime=45us PortTPowerOnTime=50us > > > L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- > > > T_CommonMode=45us LTR1.2_Threshold=101376ns > > > L1SubCtl2: T_PwrOn=50us > > > > > > 10000:e1:00.0 Non-Volatile memory controller: Sandisk Corp WD Blue SN550 > > > NVMe > > > SSD (rev 01) (prog-if 02 [NVM Express]) > > > ... > > > Capabilities: [900 v1] L1 PM Substates > > > L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- > > > L1_PM_Substates+ > > > PortCommonModeRestoreTime=32us PortTPowerOnTime=10us > > > L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- > > > T_CommonMode=0us LTR1.2_Threshold=0ns > > > L1SubCtl2: T_PwrOn=10us > > > > > > According to "PCIe r6.0, sec 5.5.4", before enabling ASPM L1.2 on the PCIe > > > Root Port and the child NVMe, they should be programmed with the same > > > LTR1.2_Threshold value. However, they have different values in this case. > > > > > > Invoke aspm_calc_l12_info() to program the L1.2 parameters properly before > > > enable L1.2 bits of L1 PM Substates Control Register in > > > __pci_enable_link_state(). > > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394 > > > Signed-off-by: Jian-Hong Pan <jhp@xxxxxxxxxxxxx> > > > --- > > > v2: > > > - Prepare the PCIe LTR parameters before enable L1 Substates > > > > > > v3: > > > - Only enable supported features for the L1 Substates part > > > > > > v4: > > > - Focus on fixing L1.2 parameters, instead of re-initializing whole L1SS > > > > > > v5: > > > - Fix typo and commit message > > > - Split introducing aspm_get_l1ss_cap() to "PCI/ASPM: Introduce > > > aspm_get_l1ss_cap()" > > > > > > drivers/pci/pcie/aspm.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > > > index c55ac11faa73..553327dee991 100644 > > > --- a/drivers/pci/pcie/aspm.c > > > +++ b/drivers/pci/pcie/aspm.c > > > @@ -1402,6 +1402,8 @@ EXPORT_SYMBOL(pci_disable_link_state); > > > static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool > > > locked) > > > { > > > struct pcie_link_state *link = pcie_aspm_get_link(pdev); > > > + struct pci_dev *child = link->downstream, *parent = link->pdev; > > > + u32 parent_l1ss_cap, child_l1ss_cap; > > > > > > if (!link) > > > return -EINVAL; > > > @@ -1433,6 +1435,16 @@ static int __pci_enable_link_state(struct pci_dev > > > *pdev, int state, bool locked) > > > link->aspm_default |= ASPM_STATE_L1_1_PCIPM | > > > ASPM_STATE_L1; > > > if (state & PCIE_LINK_STATE_L1_2_PCIPM) > > > link->aspm_default |= ASPM_STATE_L1_2_PCIPM | > > > ASPM_STATE_L1; > > > + /* > > > + * Ensure L1.2 parameters: Common_Mode_Restore_Times, T_POWER_ON > > > and > > > + * LTR_L1.2_THRESHOLD are programmed properly before enable bits > > > for > > > + * L1.2, per PCIe r6.0, sec 5.5.4. > > > + */ > > > + if (state & link->aspm_capable & ASPM_STATE_L1_2_MASK) { > > > > This is still mixing PCIE_LINK_STATE flags with ASPM_STATE flags. > > Thanks for your review, but I notice some description in PCIe spec, > 5.5.4 L1 PM Substates Configuration: > "Prior to setting either or both of the enable bits for L1.2, the > values for TPOWER_ON, Common_Mode_Restore_Time, and, if the ASPM L1.2 > Enable bit is to be Set, the LTR_L1.2_THRESHOLD (both Value and Scale > fields) must be programmed." => I think this includes both "ASPM L1.2 > Enable" and "PCI-PM L1.2 Enable" bits. That's fine. While the spec clearly calls out the ASPM L1.2 Enable bit here, I see no harm in including PCI-PM L1.2 in that check. This is what the code already does in aspm_l1ss_init(). The issue is the mixed used of two different types of flags that don't have the same meaning. 'state' contains PCIE_LINK_STATE flags which are part of the caller API to the pci_<enabled/disable>_link_state() functions. The ASPM_STATE flags are used internally to aspm.c to track all states and their meaningful combinations such as ASPM_STATE_L1_2_MASK which includes ASPM L1.2 and PCI-PM L1.2. You should not do bit operations between them. Also, you should not require that the timings be calculated only if L1_2 is enabled. You should calculate the timings as long as it's capable. This is also what aspm_l1ss_init() does. The confusion might be over the fact that you are having __pci_enable_link_state() call aspm_calc_l12_info(). This should have been handled during initialization of the link in aspm_l1ss_init() and I'm not sure why it didn't. Maybe it's because, for VMD, ASPM default state would have started out all disabled and this somehow led to aspm_l1ss_init() not getting called. But looking through the code I don't see it. It would be great if you can confirm why they weren't calculated before. David > > Jain-Hong Pan > > > 'state' should not even matter. > > The timings should always be calculated and programmed as long > > as L1_2 is capable. That way the timings are ready even if L1_2 isn't being > > enabled now (in case the user enables it later). > > > > David > > > > > + parent_l1ss_cap = aspm_get_l1ss_cap(parent); > > > + child_l1ss_cap = aspm_get_l1ss_cap(child); > > > + aspm_calc_l12_info(link, parent_l1ss_cap, child_l1ss_cap); > > > + } > > > pcie_config_aspm_link(link, policy_to_aspm_state(link)); > > > > > > link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; > >
