Mario Limonciello 3ae8fd4157 rtc: mc146818-lib: Fix the AltCentury for AMD platforms ... Setting the century forward has been failing on AMD platforms. There was a previous attempt at fixing this for family 0x17 as part of commit 7ad295d519 ("rtc: Fix the AltCentury value on AMD/Hygon platform") but this was later reverted due to some problems reported that appeared to stem from an FW bug on a family 0x17 desktop system. The same comments mentioned in the previous commit continue to apply to the newer platforms as well. ``` MC146818 driver use function mc146818_set_time() to set register RTC_FREQ_SELECT(RTC_REG_A)'s bit4-bit6 field which means divider stage reset value on Intel platform to 0x7. While AMD/Hygon RTC_REG_A(0Ah)'s bit4 is defined as DV0 [Reference]: DV0 = 0 selects Bank 0, DV0 = 1 selects Bank 1. Bit5-bit6 is defined as reserved. DV0 is set to 1, it will select Bank 1, which will disable AltCentury register(0x32) access. As UEFI pass acpi_gbl_FADT.century 0x32 (AltCentury), the CMOS write will be failed on code: CMOS_WRITE(century, acpi_gbl_FADT.century). Correct RTC_REG_A bank select bit(DV0) to 0 on AMD/Hygon CPUs, it will enable AltCentury(0x32) register writing and finally setup century as expected. ``` However in closer examination the change previously submitted was also modifying bits 5 & 6 which are declared reserved in the AMD documentation. So instead modify just the DV0 bank selection bit. Being cognizant that there was a failure reported before, split the code change out to a static function that can also be used for exclusions if any regressions such as Mikhail's pop up again. Cc: Jinke Fan <fanjinke@hygon.cn> Cc: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Link: https://lore.kernel.org/all/CABXGCsMLob0DC25JS8wwAYydnDoHBSoMh2_YLPfqm3TTvDE-Zw@mail.gmail.com/ Link: https://www.amd.com/system/files/TechDocs/51192_Bolton_FCH_RRG.pdf Signed-off-by: Raul E Rangel <rrangel@chromium.org> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20220111225750.1699-1-mario.limonciello@amd.com		2022-03-29 22:45:31 +02:00
..
acpi	USB/Thunderbolt changes for 5.17-rc1	2022-01-12 11:27:57 -08:00
asm-generic	bitmap patches for 5.17-rc1	2022-01-23 06:20:44 +02:00
clocksource
crypto	lib/crypto: blake2s: move hmac construction into wireguard	2022-01-18 13:03:55 +01:00
drm
dt-bindings	dt-bindings: rtc: sun6i: Add H616, R329, and D1 support	2022-02-15 23:14:59 +01:00
keys	keys: X.509 public key issuer lookup without AKID	2022-01-09 00:18:42 +02:00
kunit	kunit: replace kernel.h with the necessary inclusions	2022-01-20 08:52:54 +02:00
kvm	RISCV:	2022-01-16 16:15:14 +02:00
linux	rtc: mc146818-lib: Fix the AltCentury for AMD platforms	2022-03-29 22:45:31 +02:00
math-emu
media
memory
misc
net	Networking fixes for 5.17-rc1, including fixes from netfilter, bpf.	2022-01-20 10:57:05 +02:00
pcmcia
ras	mm/hwpoison: remove MF_MSG_BUDDY_2ND and MF_MSG_POISONED_HUGE	2022-01-15 16:30:31 +02:00
rdma	RDMA/core: Calculate UDP source port based on flow label or lqpn/rqpn	2022-01-07 19:34:01 -04:00
scsi	Merge branch 'akpm' (patches from Andrew)	2022-01-22 11:28:23 +02:00
soc	Networking changes for 5.17.	2022-01-10 19:06:09 -08:00
sound	ASoC: Updates for v5.17	2022-01-10 14:33:42 +01:00
target
trace	fscache fixes	2022-01-22 10:59:32 +02:00
uapi	rtc: add new RTC_FEATURE_ALARM_WAKEUP_ONLY feature	2022-03-23 19:58:40 +01:00
vdso
video
xen	xen: branch for v5.17-rc1	2022-01-12 16:42:00 -08:00