From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 30 May 2018 15:23:43 -0500 From: Bjorn Helgaas To: Mika Westerberg Cc: Bjorn Helgaas , "Rafael J . Wysocki" , Len Brown , Mario.Limonciello@dell.com, Michael Jamet , Yehezkel Bernat , Andy Shevchenko , Lukas Wunner , linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, David Keck Subject: Re: [PATCH v8 2/7] PCI: Introduce shpchp_is_native() Message-ID: <20180530202343.GO39853@bhelgaas-glaptop.roam.corp.google.com> References: <20180528124756.78512-1-mika.westerberg@linux.intel.com> <20180528124756.78512-3-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180528124756.78512-3-mika.westerberg@linux.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-ID: [+cc David] On Mon, May 28, 2018 at 03:47:51PM +0300, Mika Westerberg wrote: > In the same way we do for pciehp, introduce a new function > shpchp_is_native() that returns true whether the bridge should be > handled by the native SHCP driver. Then convert the driver to use this > function. > > Signed-off-by: Mika Westerberg > --- > drivers/pci/hotplug/acpi_pcihp.c | 4 ++-- > drivers/pci/hotplug/shpchp_core.c | 2 -- > drivers/pci/pci-acpi.c | 21 +++++++++++++++++++++ > include/linux/pci_hotplug.h | 2 ++ > 4 files changed, 25 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c > index 597d22aeefc1..3979f89b250a 100644 > --- a/drivers/pci/hotplug/acpi_pcihp.c > +++ b/drivers/pci/hotplug/acpi_pcihp.c > @@ -83,11 +83,11 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev) > * OSHP within the scope of the hotplug controller and its parents, > * up to the host bridge under which this controller exists. > */ > - host = pci_find_host_bridge(pdev->bus); > - if (host->native_shpc_hotplug) > + if (shpchp_is_native(pdev)) > return 0; > > /* If _OSC exists, we should not evaluate OSHP */ > + host = pci_find_host_bridge(pdev->bus); > root = acpi_pci_find_root(ACPI_HANDLE(&host->dev)); > if (root->osc_support_set) > goto no_control; > diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c > index 47decc9b3bb3..0f3711404c2b 100644 > --- a/drivers/pci/hotplug/shpchp_core.c > +++ b/drivers/pci/hotplug/shpchp_core.c > @@ -275,8 +275,6 @@ static int is_shpc_capable(struct pci_dev *dev) > if (dev->vendor == PCI_VENDOR_ID_AMD && > dev->device == PCI_DEVICE_ID_AMD_GOLAM_7450) > return 1; > - if (!pci_find_capability(dev, PCI_CAP_ID_SHPC)) > - return 0; > if (acpi_get_hp_hw_control_from_firmware(dev)) > return 0; > return 1; > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > index 52b8434d4d6e..bb83be0d0e5b 100644 > --- a/drivers/pci/pci-acpi.c > +++ b/drivers/pci/pci-acpi.c > @@ -394,6 +394,27 @@ bool pciehp_is_native(struct pci_dev *bridge) > return host->native_pcie_hotplug; > } > > +/** > + * shpchp_is_native - Check whether a hotplug port is handled by the OS > + * @bridge: Hotplug port to check > + * > + * Returns true if the given @bridge is handled by the native SHPC hotplug > + * driver. > + */ > +bool shpchp_is_native(struct pci_dev *bridge) > +{ > + const struct pci_host_bridge *host; > + > + if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC)) > + return false; > + > + if (!pci_find_capability(bridge, PCI_CAP_ID_SHPC)) > + return false; > + > + host = pci_find_host_bridge(bridge->bus); > + return host->native_shpc_hotplug; > +} This is sort-of-but-not-exactly the same as is_shpc_capable(). For PCI_DEVICE_ID_AMD_GOLAM_7450, is_shpc_capable() will return true and shpchp will claim the device, but shpchp_is_native() will return false because there's no SHPC capability. At least that's my interpretation of the AMD GOLAM stuff. I don't have a spec for it, but if GOLAM did have an SHPC capability, I assume is_shpc_capable() would look for it *before* testing for GOLAM. So I think these two things need to be reconciled somehow. I mentioned this before, but it was buried at the bottom of a long email, sorry about that. I wish we had a spec or details about the erratum. It looks like it's been there "forever": https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/drivers/pci/hotplug/shpchp.h?id=c16b4b14d9806e639f4afefa2d651a857a212afe But neither GOLAM (0x7450) nor POGO (0x7458) is in the PCI database at https://pci-ids.ucw.cz/read/PC/1002, so who knows if those chips ever even saw the light of day. I'll cc the author of 53044f357448 ("[PATCH] PCI Hotplug: shpchp: AMD POGO errata fix") But that was 12 years ago, so the email address may not even work any more. > /** > * pci_acpi_wake_bus - Root bus wakeup notification fork function. > * @context: Device wakeup context. > diff --git a/include/linux/pci_hotplug.h b/include/linux/pci_hotplug.h > index 1f5c935eb0de..4c378368215c 100644 > --- a/include/linux/pci_hotplug.h > +++ b/include/linux/pci_hotplug.h > @@ -164,6 +164,7 @@ struct hotplug_params { > int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp); > bool pciehp_is_native(struct pci_dev *bridge); > int acpi_get_hp_hw_control_from_firmware(struct pci_dev *bridge); > +bool shpchp_is_native(struct pci_dev *bridge); > int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle); > int acpi_pci_detect_ejectable(acpi_handle handle); > #else > @@ -178,5 +179,6 @@ static inline int acpi_get_hp_hw_control_from_firmware(struct pci_dev *bridge) > return 0; > } > static inline bool pciehp_is_native(struct pci_dev *bridge) { return true; } > +static inline bool shpchp_is_native(struct pci_dev *bridge) { return true; } > #endif > #endif > -- > 2.17.0 >