Hi Andy, On Mon, 21 Oct 2019 at 01:52, Andy Shevchenko <andy.shevche...@gmail.com> wrote: > > On Mon, Oct 21, 2019 at 7:24 AM Simon Glass <s...@chromium.org> wrote: > > > > In TPL we try to minimise code size so do not include the PCI subsystem. > > We can use fixed BARs and drivers can directly program the devices that > > they need. > > > > However we do need to bind the devices on the PCI bus and without PCI this > > does not ordinarily happen. As a work-around, define a fake PCI bus which > > does this binding, but no other PCI operations. This is a convenient way > > to ensure that we can use the same device tree for TPL, SPL and U-Boot > > proper: > > > > TPL - CONFIG_TPL_PCI is not set (no auto-config, fake PCI bus) > > SPL - CONFIG_SPL_PCI is set (no auto-config but with real PCI bus) > > U-Boot - CONFIG_PCI is set (full auto-config after relocation) > > PCI(e) bus is present in a lot of SoCs (not exclusively x86). Perhaps > better idea is to have something like lib/pci.c with minimum support > for PCI type 1 and probably PCI type 2 accessors and other very basic > functions.
I don't know of any use case for PCI in TPL on other platforms. x86 is I think unique in that it requires PCI to do anything. For other platforms I am familiar with they can boot a fair way without it. I do want to avoid the premature-optimisation problem, i.e. inventing new use cases that no one uses. The only thing we really know right now is that we need this for newer x86 platforms. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
