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| author | Rajneesh Bhardwaj <rajneesh.bhardwaj@intel.com> | 2018-03-29 20:36:55 +0530 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-04-27 16:44:29 +0200 |
| commit | f79b1c573cb4dc551919f81ed5797419f6fc1f3a (patch) | |
| tree | 03e8a7b088a7dc53a45914228eecd5d81ed29f4d /arch/x86/include/asm | |
| parent | 0644f186fc9d77bb5bd198369e59fb28927a3692 (diff) | |
| download | linux-stable-f79b1c573cb4dc551919f81ed5797419f6fc1f3a.tar.gz linux-stable-f79b1c573cb4dc551919f81ed5797419f6fc1f3a.tar.bz2 linux-stable-f79b1c573cb4dc551919f81ed5797419f6fc1f3a.zip | |
x86/i8237: Register device based on FADT legacy boot flag
From Skylake onwards, the platform controller hub (Sunrisepoint PCH) does
not support legacy DMA operations to IO ports 81h-83h, 87h, 89h-8Bh, 8Fh.
Currently this driver registers as syscore ops and its resume function is
called on every resume from S3. On Skylake and Kabylake, this causes a
resume delay of around 100ms due to port IO operations, which is a problem.
This change allows to load the driver only when the platform bios
explicitly supports such devices or has a cut-off date earlier than 2017
due to the following reasons:
- The platforms released before year 2017 have support for the 8237.
(except Sunrisepoint PCH e.g. Skylake)
- Some of the BIOS that were released for platforms (Skylake, Kabylake)
during 2016-17 are buggy. These BIOS do not set/unset the
ACPI_FADT_LEGACY_DEVICES field in FADT table properly based on the
presence or absence of the DMA device.
Very recently, open source system firmware like coreboot started unsetting
ACPI_FADT_LEGACY_DEVICES field in FADT table if the 8237 DMA device is not
present on the PCH.
Please refer to chapter 21 of 6th Generation Intel® Core™ Processor
Platform Controller Hub Family: BIOS Specification.
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: rjw@rjwysocki.net
Cc: hpa@zytor.com
Cc: Alan Cox <alan@linux.intel.com>
Link: https://lkml.kernel.org/r/1522336015-22994-1-git-send-email-anshuman.gupta@intel.com
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/x86_init.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h index ce8b4da07e35..db98e3ab3295 100644 --- a/arch/x86/include/asm/x86_init.h +++ b/arch/x86/include/asm/x86_init.h @@ -301,5 +301,6 @@ extern struct x86_apic_ops x86_apic_ops; extern void x86_early_init_platform_quirks(void); extern void x86_init_noop(void); extern void x86_init_uint_noop(unsigned int unused); +extern bool x86_pnpbios_disabled(void); #endif |