On Wed, Apr 23, 2014 at 12:03:47PM +0100, Arnd Bergmann wrote: > On Wednesday 23 April 2014 18:19:30 Kukjin Kim wrote: > > > > > Basically, ARMv8 based GH7 has same PCIe hardware IP with previous ARMv7 > > based exynos5440, several features in PCIe are different though. In other > > words, basic functionalities for PCIe are same. So I think, would be nice if > > we could use one PCIe device driver for both SoCs. > > Ok, I see. I was just trying to get a feeling for how much is shared > or SoC specific between your variants. If they are different enough, > it may be easier to have two drivers. > > > However, if we need to support the PCIe with each own device driver because > > of difference of 32bit and 64bit, please kindly let us know. Honestly, I'm > > not sure about that right now. > > We are working already on ideas to minimize the differences between > arm32 and arm64 PCI support, it will just take more work. > > > > Also, if gh7 is expected to run a full firmware, I think you should > > > do all the setup in the firmware before booting Linux, and just > > > do the required run-time operations in the driver itself. > > > > > Well, we're expecting that all the setup should be done by the device driver > > in kernel not firmware. > > Ok, just make sure this hardware never shows up in servers then. Not necessarily, as long as the setup will always happen in the kernel? > > Unfortunately we are in a tricky situation on arm64 because we have > to support both server-type SoCs and embedded-type SoCs. In an > embedded system, you can't trust the boot loader to do a proper > setup of all the hardware, so the kernel needs full control over > all the initialization. In a server, the initialization is the > responsibility of the firmware, and we don't want the kernel to > even know about those registers. > > My hope is that all server chips use an SBSA compliant PCIe > implementation, but we already have X-Gene, which is doing server > workloads with a nonstandard PCIe, and it's possible that there > will also be server-like systems with a DesignWare PCIe block > instead of an SBSA compliant one. We can still support those, but > I don't want to see more than one implementation of dw-pcie > on servers. Just like we have the generic PCIe support that Will > is doing for virtual machines and SBSA compliant systems, we > would do one dw-pcie variant for all systems that come with a > host firmware and rely on it being set up already. There is nothing in the SBSA that mandates firmware setup. All it requires is that hardware is setup in a way that is not specific to a board or a particular OEM. Surely if the setup being done for GH7 is always the same it should fit the bill? Kind regards, Liviu > > Arnd > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
