From: Arnd Bergmann <arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, linaro-kernel@lists.linaro.org, linux-pci <linux-pci@vger.kernel.org>, Liviu Dudau <Liviu.Dudau@arm.com>, LKML <linux-kernel@vger.kernel.org>, Will Deacon <Will.Deacon@arm.com>, Catalin Marinas <Catalin.Marinas@arm.com>, Bjorn Helgaas <bhelgaas@google.com> Subject: Re: [PATCH v2 4/4] pci: Add support for creating a generic host_bridge from device tree Date: Fri, 28 Feb 2014 09:46:39 +0100 [thread overview] Message-ID: <41426943.fCMrEO9t9X@wuerfel> (raw) In-Reply-To: <1393543924.14012.56.camel@pasglop> On Friday 28 February 2014 10:32:04 Benjamin Herrenschmidt wrote: > On Thu, 2014-02-27 at 14:38 +0100, Arnd Bergmann wrote: > > On Thursday 27 February 2014 13:06:42 Liviu Dudau wrote: > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > > > Please add Benjamin Herrenschmidt to Cc here, I think it would be helpful > > to get his input so we can make this work on powerpc as well. > > Tricky... We would need hooks which would turn the whole thing into a > pile of spaghetti. I think we should stick to using the range helpers > (Andrew latest patch), which makes the powerpc code a lot smaller, > and leave it at that. We can certainly do both: small helpers that let you shrink the powerpc code, and a generic implementation that can be shared by some of the other architectures that you don't use. The PCI core already uses a number of 'weak' functions here, and we can expand on that. > > + res = kzalloc(sizeof(struct resource), GFP_KERNEL); > > > + if (!res) { > > > + err = -ENOMEM; > > > + goto bridge_ranges_nomem; > > > + } > > > + > > > + of_pci_range_to_resource(&range, dev, res); > > > + > > > + if (resource_type(res) == IORESOURCE_IO) > > > + *io_base = range.cpu_addr; > > You don't care about the size of the IO space ? We probably should. The ARM code currently assumes that each I/O space is 64KB, but for a generic implementation we probably want to handle both smaller and larger windows. I suggested not supporting more than 1MB though, which is the maximum that I can see a reason for, i.e. the pci-mvebu fake host bridge that has to combine multiple per-port HW I/O spaces into one logical space. > > > + pci_add_resource_offset(resources, res, > > > + res->start - range.pci_addr); > > > + } > > > > This is not the correct resource for I/O space at all. Please talk > > to Will, I've been over this with him in detail and he probably > > understands it now. I assume you are both working in the same > > building. > > Yes, the IO offsets work differently on powerpc as well As I noticed later, the first patch in the series actually changes the range_to_resource parser to return the logical start here, which would make the offset correct even on powerpc, but unfortunately I think that cannot work. > > > +struct pci_host_bridge * > > > +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops, void *host_data) > > > +{ > > > + int err, domain, busno; > > > + struct resource bus_range; > > > + struct pci_bus *root_bus; > > > + struct pci_host_bridge *bridge; > > > + resource_size_t io_base; > > > + LIST_HEAD(res); > > > + > > > + domain = of_alias_get_id(parent->of_node, "pci-domain"); > > > + if (domain == -ENODEV) > > > + domain = domain_nr++; > > > > We probably want some uniqueness testing here. I thought this at first too, but as Liviu mentioned, this does get caught later when trying to create the root bus with a conflicting number. What the above code cannot do is to put multiple host bridges into the same domain, using distinct bus ranges. This is an intentional simplification over what some architectures currently do, and we could not see a reason why you would still need to put multiple host bridges into one domain in 2014. x86 with ACPI does it, but they won't call of_create_pci_host_bridge. Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 4/4] pci: Add support for creating a generic host_bridge from device tree Date: Fri, 28 Feb 2014 09:46:39 +0100 [thread overview] Message-ID: <41426943.fCMrEO9t9X@wuerfel> (raw) In-Reply-To: <1393543924.14012.56.camel@pasglop> On Friday 28 February 2014 10:32:04 Benjamin Herrenschmidt wrote: > On Thu, 2014-02-27 at 14:38 +0100, Arnd Bergmann wrote: > > On Thursday 27 February 2014 13:06:42 Liviu Dudau wrote: > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> > > > > Please add Benjamin Herrenschmidt to Cc here, I think it would be helpful > > to get his input so we can make this work on powerpc as well. > > Tricky... We would need hooks which would turn the whole thing into a > pile of spaghetti. I think we should stick to using the range helpers > (Andrew latest patch), which makes the powerpc code a lot smaller, > and leave it at that. We can certainly do both: small helpers that let you shrink the powerpc code, and a generic implementation that can be shared by some of the other architectures that you don't use. The PCI core already uses a number of 'weak' functions here, and we can expand on that. > > + res = kzalloc(sizeof(struct resource), GFP_KERNEL); > > > + if (!res) { > > > + err = -ENOMEM; > > > + goto bridge_ranges_nomem; > > > + } > > > + > > > + of_pci_range_to_resource(&range, dev, res); > > > + > > > + if (resource_type(res) == IORESOURCE_IO) > > > + *io_base = range.cpu_addr; > > You don't care about the size of the IO space ? We probably should. The ARM code currently assumes that each I/O space is 64KB, but for a generic implementation we probably want to handle both smaller and larger windows. I suggested not supporting more than 1MB though, which is the maximum that I can see a reason for, i.e. the pci-mvebu fake host bridge that has to combine multiple per-port HW I/O spaces into one logical space. > > > + pci_add_resource_offset(resources, res, > > > + res->start - range.pci_addr); > > > + } > > > > This is not the correct resource for I/O space at all. Please talk > > to Will, I've been over this with him in detail and he probably > > understands it now. I assume you are both working in the same > > building. > > Yes, the IO offsets work differently on powerpc as well As I noticed later, the first patch in the series actually changes the range_to_resource parser to return the logical start here, which would make the offset correct even on powerpc, but unfortunately I think that cannot work. > > > +struct pci_host_bridge * > > > +of_create_pci_host_bridge(struct device *parent, struct pci_ops *ops, void *host_data) > > > +{ > > > + int err, domain, busno; > > > + struct resource bus_range; > > > + struct pci_bus *root_bus; > > > + struct pci_host_bridge *bridge; > > > + resource_size_t io_base; > > > + LIST_HEAD(res); > > > + > > > + domain = of_alias_get_id(parent->of_node, "pci-domain"); > > > + if (domain == -ENODEV) > > > + domain = domain_nr++; > > > > We probably want some uniqueness testing here. I thought this at first too, but as Liviu mentioned, this does get caught later when trying to create the root bus with a conflicting number. What the above code cannot do is to put multiple host bridges into the same domain, using distinct bus ranges. This is an intentional simplification over what some architectures currently do, and we could not see a reason why you would still need to put multiple host bridges into one domain in 2014. x86 with ACPI does it, but they won't call of_create_pci_host_bridge. Arnd
next prev parent reply other threads:[~2014-02-28 8:46 UTC|newest] Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-02-27 13:06 [PATCH v2 0/4] [RFC] Support for creating generic host_bridge from device tree Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau [not found] ` < 1393506402-11474-5-git-send-email-Liviu.Dudau@arm.com> 2014-02-27 13:06 ` [PATCH v2 1/4] pci: OF: Fix the conversion of IO ranges into IO resources Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:20 ` Arnd Bergmann 2014-02-27 13:20 ` Arnd Bergmann 2014-02-27 13:20 ` Arnd Bergmann 2014-02-27 13:45 ` Liviu Dudau 2014-02-27 13:22 ` Andrew Murray 2014-02-27 13:22 ` Andrew Murray 2014-02-27 13:56 ` Liviu Dudau 2014-02-27 14:08 ` Arnd Bergmann 2014-02-27 14:21 ` Liviu Dudau 2014-02-27 16:00 ` Arnd Bergmann 2014-02-27 14:30 ` Liviu Dudau 2014-02-27 13:58 ` Arnd Bergmann 2014-02-27 13:58 ` Arnd Bergmann 2014-02-27 18:19 ` Jason Gunthorpe 2014-02-27 18:19 ` Jason Gunthorpe 2014-02-27 19:12 ` Liviu Dudau 2014-02-27 19:12 ` Liviu Dudau 2014-02-27 19:12 ` Liviu Dudau 2014-02-27 19:36 ` Jason Gunthorpe 2014-02-27 19:36 ` Jason Gunthorpe 2014-02-27 19:36 ` Jason Gunthorpe 2014-02-27 19:48 ` Arnd Bergmann 2014-02-27 19:48 ` Arnd Bergmann 2014-02-27 20:07 ` Jason Gunthorpe 2014-02-27 20:07 ` Jason Gunthorpe 2014-02-27 20:22 ` Arnd Bergmann 2014-02-27 20:22 ` Arnd Bergmann 2014-02-27 20:22 ` Arnd Bergmann 2014-02-28 12:50 ` Liviu Dudau 2014-02-28 12:50 ` Liviu Dudau 2014-02-28 12:50 ` Liviu Dudau 2014-02-27 13:06 ` [PATCH v2 2/4] pci: Create pci_host_bridge before its associated bus in pci_create_root_bus Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:22 ` Arnd Bergmann 2014-02-27 13:22 ` Arnd Bergmann 2014-02-27 13:06 ` [PATCH v2 3/4] pci: Introduce a domain number for pci_host_bridge Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:22 ` Arnd Bergmann 2014-02-27 13:22 ` Arnd Bergmann 2014-02-27 13:06 ` [PATCH v2 4/4] pci: Add support for creating a generic host_bridge from device tree Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:06 ` Liviu Dudau 2014-02-27 13:38 ` Arnd Bergmann 2014-02-27 13:38 ` Arnd Bergmann 2014-02-27 13:48 ` Arnd Bergmann 2014-02-27 13:48 ` Arnd Bergmann 2014-02-27 13:48 ` Arnd Bergmann 2014-02-27 14:13 ` Liviu Dudau 2014-02-27 15:58 ` Arnd Bergmann 2014-02-27 16:20 ` Liviu Dudau 2014-02-27 16:45 ` Arnd Bergmann 2014-02-27 16:54 ` Liviu Dudau 2014-02-27 18:42 ` Arnd Bergmann 2014-02-27 23:32 ` Benjamin Herrenschmidt 2014-02-27 23:32 ` Benjamin Herrenschmidt 2014-02-27 23:32 ` Benjamin Herrenschmidt 2014-02-28 8:46 ` Arnd Bergmann [this message] 2014-02-28 8:46 ` Arnd Bergmann 2014-02-28 9:55 ` Liviu Dudau 2014-02-28 9:55 ` Liviu Dudau 2014-03-02 1:23 ` Benjamin Herrenschmidt 2014-03-02 1:23 ` Benjamin Herrenschmidt 2014-03-02 1:23 ` Benjamin Herrenschmidt 2014-03-02 1:25 ` Benjamin Herrenschmidt 2014-03-02 1:25 ` Benjamin Herrenschmidt 2014-03-07 18:58 ` Grant Likely 2014-03-07 18:58 ` Grant Likely 2014-03-07 18:58 ` Grant Likely
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