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| author | Arvind Sankar <nivedita@alum.mit.edu> | 2019-12-24 14:29:07 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-23 08:22:38 +0100 |
| commit | 2c490a4730c46cb6ddbfb0c54e687e0efd9ed7ef (patch) | |
| tree | 0562eadb4696b91f1c9159cd0de4aec51d755ec5 /drivers/firmware | |
| parent | 1241e815b88e52a92894d170219a36d0942888ff (diff) | |
| download | linux-stable-2c490a4730c46cb6ddbfb0c54e687e0efd9ed7ef.tar.gz linux-stable-2c490a4730c46cb6ddbfb0c54e687e0efd9ed7ef.tar.bz2 linux-stable-2c490a4730c46cb6ddbfb0c54e687e0efd9ed7ef.zip | |
efi/earlycon: Fix write-combine mapping on x86
commit d92b54570d24d017d2630e314b525ed792f5aa6c upstream.
On x86, until PAT is initialized, WC translates into UC-. Since we
calculate and store pgprot_writecombine(PAGE_KERNEL) when earlycon is
initialized, this means we actually use UC- mappings instead of WC
mappings, which makes scrolling very slow.
Instead store a boolean flag to indicate whether we want to use
writeback or write-combine mappings, and recalculate the actual pgprot_t
we need on every mapping. Once PAT is initialized, we will start using
write-combine mappings, which speeds up the scrolling considerably.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 69c1f396f25b ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation")
Link: https://lkml.kernel.org/r/20191224132909.102540-2-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/earlycon.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c index d4077db6dc97..5d4f84781aa0 100644 --- a/drivers/firmware/efi/earlycon.c +++ b/drivers/firmware/efi/earlycon.c @@ -17,7 +17,7 @@ static const struct console *earlycon_console __initdata; static const struct font_desc *font; static u32 efi_x, efi_y; static u64 fb_base; -static pgprot_t fb_prot; +static bool fb_wb; static void *efi_fb; /* @@ -33,10 +33,8 @@ static int __init efi_earlycon_remap_fb(void) if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED)) return 0; - if (pgprot_val(fb_prot) == pgprot_val(PAGE_KERNEL)) - efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WB); - else - efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WC); + efi_fb = memremap(fb_base, screen_info.lfb_size, + fb_wb ? MEMREMAP_WB : MEMREMAP_WC); return efi_fb ? 0 : -ENOMEM; } @@ -53,9 +51,12 @@ late_initcall(efi_earlycon_unmap_fb); static __ref void *efi_earlycon_map(unsigned long start, unsigned long len) { + pgprot_t fb_prot; + if (efi_fb) return efi_fb + start; + fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL); return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot)); } @@ -215,10 +216,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device, if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) fb_base |= (u64)screen_info.ext_lfb_base << 32; - if (opt && !strcmp(opt, "ram")) - fb_prot = PAGE_KERNEL; - else - fb_prot = pgprot_writecombine(PAGE_KERNEL); + fb_wb = opt && !strcmp(opt, "ram"); si = &screen_info; xres = si->lfb_width; |