On Tue, Jan 06, 2015 at 01:59:27PM +0000, Arnd Bergmann wrote: > On Tuesday 06 January 2015 11:20:01 Catalin Marinas wrote: > > On Mon, Jan 05, 2015 at 08:16:30PM +0000, Arnd Bergmann wrote: > > > On Monday 05 January 2015 13:13:02 Catalin Marinas wrote: > > > > > since passing no DT tables to OS but > > > > > acpi=force is missing is a corner case, we can do a follow up patch to > > > > > fix that, does it make sense? > > > > > > > > Not entirely. Why would no dtb and no acpi=force be a corner case? I > > > > thought this should be the default when only ACPI tables are passed, no > > > > need for an additional acpi=force argument. > > > > > > We don't really support the case of only ACPI tables for now. The expectation > > > is that you always have working DT support, at least for the next few years > > > as ACPI features are ramping up, and without acpi=force it should not try > > > to use ACPI at all. > > > > So if both DT and ACPI are present, just use DT unless acpi=force is > > passed. So far I think we agree but what I want to avoid is always > > mandating acpi=force even when the DT tables are missing (in the long > > run). > > > > Now, what's preventing a vendor firmware from providing only ACPI > > tables? Do we enforce it in some way (arm-acpi.txt, kernel warning etc.) > > that both DT and ACPI are supported, or at least that dts files are > > merged in the kernel first? > > We have no way of enforcing what a board vendor ships, so if they want > to have ACPI-only machines for MS Windows, they just won't work by > default on Linux. What do you mean by "won't work by default on Linux"? Assuming no additional drivers are needed (i.e. a few devices mentioned in SBSA and the rest on a PCIe bus, using existing drivers without further modifications), do you still want mainline to fail to boot on such ACPI-only systems? > Once ACPI support is mature enough, we can also have a whitelist or a > different default for using it automatically when no DT is present. Having a white-list requires some for of SoC identification. Does ACPI provide such thing (like "model" or "compatible" strings in the top DT node)? > For drivers merged upstream, I would insist that every driver merged > for an ARM64 platform has a documented DT binding that is used in the > driver. That's fine by me. I just hope that for hardware aimed at ACPI we won't need many non-PCIe drivers. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
