On 21 August 2017 at 16:19, Jingoo Han <jingoohan1@xxxxxxxxx> wrote: > On Friday, August 18, 2017 6:57 PM, Ard Biesheuvel wrote: >> >> Some implementations of the Synopsys Designware PCIe controller implement >> a so-called ECAM shift mode, which allows a static memory window to be >> configured that covers the configuration space of the entire bus range. >> >> If the firmware performs all the low level configuration that is required >> to expose this controller in a fully ECAM compatible manner, we can >> simply describe it as "pci-host-ecam-generic" and be done with it. >> However, it appears that in some cases (one of which is the Armada 80x0), >> the IP is synthesized with an ATU window size that does not allow the >> first bus to be mapped in a way that prevents the device on the >> downstream port from appearing more than once. >> >> So implement a driver that relies on the firmware to perform all low >> level initialization, and drives the controller in ECAM mode, but >> overrides the config space accessors to take the above quirk into >> account. >> >> Note that, unlike most drivers for this IP, this driver does not expose >> a fake bridge device at B/D/F 00:00.0. There is no point in doing so, >> given that this is not a true bridge, and does not require any windows >> to be configured in order for the downstream device to operate correctly. >> Omitting it also prevents the PCI resource allocation routines from >> handing out BAR space to it unnecessarily. >> >> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >> Cc: Jingoo Han <jingoohan1@xxxxxxxxx> >> Cc: Joao Pinto <Joao.Pinto@xxxxxxxxxxxx> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> >> --- >> >> Posted as RFC for discussion. We have systems booting with UEFI firmware > > (CC'ed Arnd Bergmann) > > Thank you for sharing this patch. > I have no objection about this patch. > Thanks. > I think that this driver is required for ARM-based server system. > But, as you wrote above, UEFI should support low-level code for this > DesignWare > Controller if we want to use this DWC-ECAM driver. So, can we get the UEFI > code > for this controller? > > If not, can you share your plan about that? > Yes, I will share the code via the edk2-platforms tree as soon as we are ready to publish support for this particular platform.
