diff options
| author | Stephen Boyd <sboyd@codeaurora.org> | 2014-11-10 21:56:41 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-11-21 16:24:43 +0100 |
| commit | 6c96a4a6e249a0580b32893583771149e0611375 (patch) | |
| tree | d4a695457221a336518c261b5e6601259bf7a510 /arch/arm/include/asm/vfp.h | |
| parent | ARM: 8196/1: vfp: Workaround bad MVFR1 register on some Kraits (diff) | |
| download | linux-6c96a4a6e249a0580b32893583771149e0611375.tar.xz linux-6c96a4a6e249a0580b32893583771149e0611375.zip | |
ARM: 8197/1: vfp: Fix VFPv3 hwcap detection on CPUID based cpus
The subarchitecture field in the fpsid register is 7 bits wide on
ARM CPUs using the CPUID identification scheme, spanning bits 22
to 16. The topmost bit is used to designate that the
subarchitecture designer is not ARM when it is set to 1. On
non-CPUID scheme CPUs the subarchitecture field is only 4 bits
wide and the higher bits are used to indicate no double precision
support (bit 20) and the FTSMX/FLDMX format (bits 21-22).
The VFP support code only looks at bits 19-16 to determine the
VFP version. On Qualcomm's processors (Krait and Scorpion) we
should see that we have HWCAP_VFPv3 but we don't because bit 22
is set to 1 to indicate that the subarchitecture is not
implemented by ARM and the rest of the bits are left as 0 because
this is the first subarchitecture that Qualcomm has designed.
Unfortunately we can't just widen the FPSID subarchitecture
bitmask to consider all the bits on a CPUID scheme because there
may be CPUs without the CPUID scheme that have VFP without double
precision support and then the version would be a very wrong and
large number. Instead, update the version detection logic to
consider if the CPU is using the CPUID scheme.
If the CPU is using CPUID scheme, use the MVFR registers to
determine what version of VFP is supported. We already do this
for VFPv4, so do something similar for VFPv3 and look for single
or double precision support in MVFR0. Otherwise fall back to
using FPSID to detect VFP support on non-CPUID scheme CPUs. We
know that VFPv3 is only present in CPUs that have support for the
CPUID scheme so this should be equivalent.
Tested-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/vfp.h')
| -rw-r--r-- | arch/arm/include/asm/vfp.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm/include/asm/vfp.h b/arch/arm/include/asm/vfp.h index f4ab34fd4f72..ee5f3084243c 100644 --- a/arch/arm/include/asm/vfp.h +++ b/arch/arm/include/asm/vfp.h @@ -22,6 +22,7 @@ #define FPSID_NODOUBLE (1<<20) #define FPSID_ARCH_BIT (16) #define FPSID_ARCH_MASK (0xF << FPSID_ARCH_BIT) +#define FPSID_CPUID_ARCH_MASK (0x7F << FPSID_ARCH_BIT) #define FPSID_PART_BIT (8) #define FPSID_PART_MASK (0xFF << FPSID_PART_BIT) #define FPSID_VARIANT_BIT (4) @@ -75,6 +76,10 @@ /* MVFR0 bits */ #define MVFR0_A_SIMD_BIT (0) #define MVFR0_A_SIMD_MASK (0xf << MVFR0_A_SIMD_BIT) +#define MVFR0_SP_BIT (4) +#define MVFR0_SP_MASK (0xf << MVFR0_SP_BIT) +#define MVFR0_DP_BIT (8) +#define MVFR0_DP_MASK (0xf << MVFR0_DP_BIT) /* Bit patterns for decoding the packaged operation descriptors */ #define VFPOPDESC_LENGTH_BIT (9) |