From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH V2 3/5] PCI: xilinx: Modifying AXI PCIe Host Bridge driver to work on both Zynq and Microblaze Date: Thu, 28 Jan 2016 15:23:37 +0100 Message-ID: <3706176.5tvYx0gSBz@wuerfel> References: <1452620173-4905-1-git-send-email-bharatku@xilinx.com> <1917083.LB4Ng3Y2yP@wuerfel> <8520D5D51A55D047800579B094147198258741F5@XAP-PVEXMBX01.xlnx.xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <8520D5D51A55D047800579B094147198258741F5@XAP-PVEXMBX01.xlnx.xilinx.com> Sender: linux-kernel-owner@vger.kernel.org To: Bharat Kumar Gogada Cc: "bhelgaas@google.com" , Michal Simek , "lorenzo.pieralisi@arm.com" , "paul.burton@imgtec.com" , "yinghai@kernel.org" , "wangyijing@huawei.com" , "robh@kernel.org" , "russell.joyce@york.ac.uk" , Soren Brinkmann , "jiang.liu@linux.intel.com" , "pawel.moll@arm.com" , "mark.rutland@arm.com" , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , linux-p List-Id: devicetree@vger.kernel.org On Thursday 28 January 2016 14:18:15 Bharat Kumar Gogada wrote: > > > > I see. In the upstream code you seem to do it in > > pcibios_setup_bus_devices(), while arm64 and powerpc do it in > > pcibios_add_device(). > > > No that function is not getting called with generic API's, its getting called with pcibios_init flow which is tightly bound with struct pci_controller microblaze specific structure. So I added pcibios_add_device in pci-common.c. Ok > > > May be we can add similar on arm and test out, but we might need some > > > cleanup in arch/arm/kernel/bios32.c > > > > I think that would still just be a half-baked solution. This should really be fully > > automatic. We could do it in the __weak > > pcibios_add_device() for all architectures that don't override it when the bus > > was probed from DT, or we could do it in pci_read_irq(). > When will pci_read_irq() call get invoked ? This is called early on when a device gets created in pci_setup_device(), so platforms can still override the value later. The idea here is that normally a BIOS stores the interrupt number in the PCI_INTERRUPT_LINE config space byte, and we just read it from there. Generally speaking though, for non-PC systems we tend to not have a BIOS that writes these values to start with, and any values stored in here have no meaning in combination with SPARSE_IRQ and/or IRQ_DOMAINS because the bootloader or BIOS doesn't know what IRQ number will refer to hardware IRQ line in Linux. Arnd