[PATCH v4 13/15] drm/amd/display: Use ARCH_HAS_KERNEL_FPU_SUPPORT

[Samuel Holland]

Hi Thiago,

On 2024-04-10 8:02 PM, Thiago Jung Bauermann wrote:
> Samuel Holland <samuel.holland at sifive.com> writes:
>> On 2024-04-10 5:21 PM, Thiago Jung Bauermann wrote:
>>>
>>> Unfortunately this patch causes build failures on arm with allyesconfig
>>> and allmodconfig. Tested with next-20240410.
> 
> <snip>
> 
>> In both cases, the issue is that the toolchain requires runtime support to
>> convert between `unsigned long long` and `double`, even when hardware FP is
>> enabled. There was some past discussion about GCC inlining some of these
>> conversions[1], but that did not get implemented.
> 
> Thank you for the explanation and the bugzilla reference. I added a
> comment there mentioning that the problem came up again with this patch
> series.
> 
>> The short-term fix would be to drop the `select ARCH_HAS_KERNEL_FPU_SUPPORT` for
>> 32-bit arm until we can provide these runtime library functions.
> 
> Does this mean that patch 2 in this series:
> 
> [PATCH v4 02/15] ARM: Implement ARCH_HAS_KERNEL_FPU_SUPPORT
> 
> will be dropped?

No, because later patches in the series (3, 6) depend on the definition of
CC_FLAGS_FPU from that patch. I will need to send a fixup patch unless I can
find a GPL-2 compatible implementation of the runtime library functions.

Regards,
Samuel