Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756425AbcKVRMj (ORCPT ); Tue, 22 Nov 2016 12:12:39 -0500 Received: from foss.arm.com ([217.140.101.70]:34318 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755105AbcKVRMh (ORCPT ); Tue, 22 Nov 2016 12:12:37 -0500 Date: Tue, 22 Nov 2016 17:03:45 +0000 From: Lorenzo Pieralisi To: Gabriele Paoloni Cc: "liudongdong (C)" , "helgaas@kernel.org" , "arnd@arndb.de" , "rafael@kernel.org" , "tn@semihalf.com" , "Wangzhou (B)" , "pratyush.anand@gmail.com" , "linux-pci@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "jcm@redhat.com" , "Chenxin (Charles)" , "hanjun.guo@linaro.org" , Linuxarm Subject: Re: [PATCH V6 1/2] PCI/ACPI: Provide acpi_get_rc_resources() for ARM64 platform Message-ID: <20161122170345.GA2509@red-moon> References: <1479816529-97410-1-git-send-email-liudongdong3@huawei.com> <1479816529-97410-2-git-send-email-liudongdong3@huawei.com> <20161122155648.GA2022@red-moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5569 Lines: 174 On Tue, Nov 22, 2016 at 04:09:57PM +0000, Gabriele Paoloni wrote: [...] > > On Tue, Nov 22, 2016 at 08:08:48PM +0800, Dongdong Liu wrote: > > > The acpi_get_rc_resources() is used to get the RC register address > > that can > > > not be described in MCFG. It takes the _HID&segment to look for and > > returns > > > the RC address resource. Use PNP0C02 devices to describe such RC > > address > > > resource. Use _UID to match segment to tell which root bus the > > PNP0C02 > > > resource belong to. > > > > Here (ie interpreting the _UID as a segment identifier) is where we > > start interpreting the specs instead of relying on them, if you want to > > go ahead with this feel free but I do not like this attitude at all. > > Obviously there are no specs to specify the segment id of a quirk. That's the reason why _UID (or any other standard object) should not be (ab)used to do that, again, that's just my opinion. > Looking at the ACPI specs it seems to me that the _UID is no worse > than other device identification objects... There are no bindings in the specs describing what you need. If you want to say "for this _HID, _UID means something completely different - ie root bridge segment identifier - go ahead if that's fine with Bjorn and Rafael; another solution would be adding a _DSM/DSD to the PNP0c02 device to retrieve the segment number, other than that I have run out of ideas. Lorenzo > > > > > > Signed-off-by: Dongdong Liu > > > Signed-off-by: Tomasz Nowicki > > > --- > > > drivers/pci/pci-acpi.c | 69 > > ++++++++++++++++++++++++++++++++++++++++++++++++++ > > > drivers/pci/pci.h | 4 +++ > > > 2 files changed, 73 insertions(+) > > > > > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > > > index d966d47..76fd6f4 100644 > > > --- a/drivers/pci/pci-acpi.c > > > +++ b/drivers/pci/pci-acpi.c > > > @@ -29,6 +29,75 @@ > > > 0x91, 0x17, 0xea, 0x4d, 0x19, 0xc3, 0x43, 0x4d > > > }; > > > > > > +#ifdef CONFIG_ARM64 > > > > CONFIG_PCI_ECAM_QUIRKS (that you will introduce earlier in your > > series). > > > > The way you did it seems to imply that on ARM64 to get RC address we > > need to (and are allowed to) use this function (and related, *Linux > > specific*, ACPI bindings) and that's a generic way of getting config > > space. It is not and it must not be and I consider it a bit of a > > stretch > > to have it in generic code but I can live with that as long as it comes > > with its own config option that describes that this stuff is > > non-compliant code used by non-compliant platform drivers. > > Yes probably better to have > > #ifdef CONFIG_PCI_ECAM_QUIRKS > > Thanks > > Gab > > > > > Thanks, > > Lorenzo > > > > > +static struct resource *acpi_get_rc_addr(struct acpi_device *adev) > > > +{ > > > + struct resource_entry *entry; > > > + struct list_head list; > > > + unsigned long flags; > > > + int ret; > > > + struct resource *res; > > > + > > > + INIT_LIST_HEAD(&list); > > > + flags = IORESOURCE_MEM; > > > + ret = acpi_dev_get_resources(adev, &list, > > > + acpi_dev_filter_resource_type_cb, > > > + (void *) flags); > > > + if (ret <= 0) > > > + return NULL; > > > + > > > + entry = list_first_entry(&list, struct resource_entry, node); > > > + res = entry->res; > > > + acpi_dev_free_resource_list(&list); > > > + return res; > > > +} > > > + > > > +static acpi_status acpi_match_rc(acpi_handle handle, u32 lvl, void > > *context, > > > + void **retval) > > > +{ > > > + u16 *segment = context; > > > + unsigned long long uid; > > > + acpi_status status; > > > + > > > + status = acpi_evaluate_integer(handle, "_UID", NULL, &uid); > > > + if (ACPI_FAILURE(status) || uid != *segment) > > > + return AE_CTRL_DEPTH; > > > + > > > + *(acpi_handle *)retval = handle; > > > + return AE_CTRL_TERMINATE; > > > +} > > > + > > > +/** > > > + * acpi_get_rc_resources() - get the RC address resource. > > > + * @hid: HID to search for. > > > + * @segment: PCI Segment number. > > > + * > > > + * Get the RC address resource that can not be described in MCFG. It > > takes > > > + * the _HID&segment to look for and returns the RC address resource. > > Use > > > + * _CRS of PNP0C02 devices to describe such RC address resource. Use > > _UID > > > + * to match segment to tell which root bus the PNP0C02 resource > > belong to. > > > + * > > > + * Return: RC address resource. > > > + */ > > > +struct resource *acpi_get_rc_resources(const char *hid, u16 segment) > > > +{ > > > + struct acpi_device *adev; > > > + acpi_status status; > > > + acpi_handle handle; > > > + int ret; > > > + > > > + status = acpi_get_devices(hid, acpi_match_rc, &segment, &handle); > > > + if (ACPI_FAILURE(status)) > > > + return -ENODEV; > > > + > > > + ret = acpi_bus_get_device(handle, &adev); > > > + if (ret) > > > + return ret; > > > + > > > + return acpi_get_rc_addr(adev); > > > +} > > > +#endif > > > + > > > phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle) > > > { > > > acpi_status status = AE_NOT_EXIST; > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > > > index 4518562..bf1dbfe 100644 > > > --- a/drivers/pci/pci.h > > > +++ b/drivers/pci/pci.h > > > @@ -356,4 +356,8 @@ static inline int pci_dev_specific_reset(struct > > pci_dev *dev, int probe) > > > } > > > #endif > > > > > > +#if defined(CONFIG_ARM64) && defined(CONFIG_ACPI) > > > +struct resource *acpi_get_rc_resources(const char *hid, u16 > > segment); > > > +#endif > > > + > > > #endif /* DRIVERS_PCI_H */ > > > -- > > > 1.9.1 > > >