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MIPS: Loongson64: Use _CACHE_UNCACHED instead of _CACHE_UNCACHED_ACCELERATED 

Loongson64 processors have a writecombine issue that maybe failed to
write back framebuffer used with ATI Radeon or AMD GPU at times, after
commit 8a08e50cee ("drm: Permit video-buffers writecombine mapping
for MIPS"), there exists some errors such as blurred screen and lockup,
and so on.

[   60.958721] radeon 0000:03:00.0: ring 0 stalled for more than 10079msec
[   60.965315] radeon 0000:03:00.0: GPU lockup (current fence id 0x0000000000000112 last fence id 0x000000000000011d on ring 0)
[   60.976525] radeon 0000:03:00.0: ring 3 stalled for more than 10086msec
[   60.983156] radeon 0000:03:00.0: GPU lockup (current fence id 0x0000000000000374 last fence id 0x00000000000003a8 on ring 3)

As discussed earlier [1], it might be better to disable writecombine
on the CPU detection side because the root cause is unknown now.

Actually, this patch is a temporary solution to just make it work well,
it is not a proper and final solution, I hope someone will have a better
solution to fix this issue in the future.

[1] https://lore.kernel.org/patchwork/patch/1285542/

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Tiezhu Yang 2021-04-06 17:25:12 +08:00 committed by Thomas Bogendoerfer
parent 04324f44cb
commit 5e65c52ec7
1 changed files with 0 additions and 3 deletions
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3
arch/mips/kernel/cpu-probe.c
View File

@ -1752,7 +1752,6 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
set_isa(c, MIPS_CPU_ISA_M64R2);
break;
}
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_EXT |
MIPS_ASE_LOONGSON_EXT2);
break;
@ -1782,7 +1781,6 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
* register, we correct it here.
*/
c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV | MIPS_CPU_LDPTE;
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
MIPS_ASE_LOONGSON_EXT | MIPS_ASE_LOONGSON_EXT2);
c->ases &= ~MIPS_ASE_VZ; /* VZ of Loongson-3A2000/3000 is incomplete */
@ -1793,7 +1791,6 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
set_elf_platform(cpu, "loongson3a");
set_isa(c, MIPS_CPU_ISA_M64R2);
decode_cpucfg(c);
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
break;
default:
panic("Unknown Loongson Processor ID!");