From 278be83601dd1725d4732241f066d528e160a39d Mon Sep 17 00:00:00 2001 From: Icenowy Zheng Date: Wed, 18 Oct 2023 08:42:52 +0800 Subject: LoongArch: Disable WUC for pgprot_writecombine() like ioremap_wc() Currently the code disables WUC only disables it for ioremap_wc(), which is only used when mapping writecombine pages like ioremap() (mapped to the kernel space). But for VRAM mapped in TTM/GEM, it is mapped with a crafted pgprot by the pgprot_writecombine() function, in which case WUC isn't disabled now. Disable WUC for pgprot_writecombine() (fallback to SUC) if needed, like ioremap_wc(). This improves the AMDGPU driver's stability (solves some misrendering) on Loongson-3A5000/3A6000 machines. Signed-off-by: Icenowy Zheng Signed-off-by: Huacai Chen --- arch/loongarch/include/asm/io.h | 5 ++--- arch/loongarch/include/asm/pgtable-bits.h | 4 +++- arch/loongarch/kernel/setup.c | 10 +++++----- 3 files changed, 10 insertions(+), 9 deletions(-) (limited to 'arch') diff --git a/arch/loongarch/include/asm/io.h b/arch/loongarch/include/asm/io.h index 0dcb36b32cb2..c486c2341b66 100644 --- a/arch/loongarch/include/asm/io.h +++ b/arch/loongarch/include/asm/io.h @@ -52,10 +52,9 @@ static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size, * @offset: bus address of the memory * @size: size of the resource to map */ -extern pgprot_t pgprot_wc; - #define ioremap_wc(offset, size) \ - ioremap_prot((offset), (size), pgprot_val(pgprot_wc)) + ioremap_prot((offset), (size), \ + pgprot_val(wc_enabled ? PAGE_KERNEL_WUC : PAGE_KERNEL_SUC)) #define ioremap_cache(offset, size) \ ioremap_prot((offset), (size), pgprot_val(PAGE_KERNEL)) diff --git a/arch/loongarch/include/asm/pgtable-bits.h b/arch/loongarch/include/asm/pgtable-bits.h index 35348d4c4209..21319c1e045c 100644 --- a/arch/loongarch/include/asm/pgtable-bits.h +++ b/arch/loongarch/include/asm/pgtable-bits.h @@ -105,13 +105,15 @@ static inline pgprot_t pgprot_noncached(pgprot_t _prot) return __pgprot(prot); } +extern bool wc_enabled; + #define pgprot_writecombine pgprot_writecombine static inline pgprot_t pgprot_writecombine(pgprot_t _prot) { unsigned long prot = pgprot_val(_prot); - prot = (prot & ~_CACHE_MASK) | _CACHE_WUC; + prot = (prot & ~_CACHE_MASK) | (wc_enabled ? _CACHE_WUC : _CACHE_SUC); return __pgprot(prot); } diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c index 7783f0a3d742..aed65915e932 100644 --- a/arch/loongarch/kernel/setup.c +++ b/arch/loongarch/kernel/setup.c @@ -161,19 +161,19 @@ static void __init smbios_parse(void) } #ifdef CONFIG_ARCH_WRITECOMBINE -pgprot_t pgprot_wc = PAGE_KERNEL_WUC; +bool wc_enabled = true; #else -pgprot_t pgprot_wc = PAGE_KERNEL_SUC; +bool wc_enabled = false; #endif -EXPORT_SYMBOL(pgprot_wc); +EXPORT_SYMBOL(wc_enabled); static int __init setup_writecombine(char *p) { if (!strcmp(p, "on")) - pgprot_wc = PAGE_KERNEL_WUC; + wc_enabled = true; else if (!strcmp(p, "off")) - pgprot_wc = PAGE_KERNEL_SUC; + wc_enabled = false; else pr_warn("Unknown writecombine setting \"%s\".\n", p); -- cgit