Loongson64 processors have a writecombine issue that maybe failed to
write back framebuffer used with ATI Radeon or AMD GPU at times, after
commit 8a08e50cee66 ("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@xxxxxxxxxxx>
---
Hi Thomas,
If you are OK with this change, could you please apply it
to mips-next? Then, no need to do this change manually every
time when update the mainline kernel.
arch/mips/kernel/cpu-probe.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index b718920..0ef240a 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -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!");
--
2.1.0
