From 3349fb64b2927407017d970dd5c4daf3c5ad69f8 Mon Sep 17 00:00:00 2001 From: Chris Bainbridge Date: Wed, 29 Apr 2015 21:21:40 +0100 Subject: [PATCH] ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook Commit 7bc5a2bad0b8 'ACPI: Support _OSI("Darwin") correctly' caused the MacBook firmware to expose the SBS, resulting in intermittent hangs of several minutes on boot, and failure to detect or report the battery. Fix this by adding a 5 us delay to the start of each SMBUS transaction. This timing is the result of experimentation - hangs were observed with 3 us but never with 5 us. Fixes: 7bc5a2bad0b8 'ACPI: Support _OSI("Darwin") correctly' Link: https://bugzilla.kernel.org/show_bug.cgi?id=94651 Signed-off-by: Chris Bainbridge Cc: 3.18+ # 3.18+ [ rjw: Subject and changelog ] Signed-off-by: Rafael J. Wysocki --- drivers/acpi/sbshc.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/acpi/sbshc.c b/drivers/acpi/sbshc.c index 26e5b5060523..bf034f8b7c1a 100644 --- a/drivers/acpi/sbshc.c +++ b/drivers/acpi/sbshc.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "sbshc.h" #define PREFIX "ACPI: " @@ -87,6 +88,8 @@ enum acpi_smb_offset { ACPI_SMB_ALARM_DATA = 0x26, /* 2 bytes alarm data */ }; +static bool macbook; + static inline int smb_hc_read(struct acpi_smb_hc *hc, u8 address, u8 *data) { return ec_read(hc->offset + address, data); @@ -132,6 +135,8 @@ static int acpi_smbus_transaction(struct acpi_smb_hc *hc, u8 protocol, } mutex_lock(&hc->lock); + if (macbook) + udelay(5); if (smb_hc_read(hc, ACPI_SMB_PROTOCOL, &temp)) goto end; if (temp) { @@ -257,12 +262,29 @@ extern int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit, acpi_handle handle, acpi_ec_query_func func, void *data); +static int macbook_dmi_match(const struct dmi_system_id *d) +{ + pr_debug("Detected MacBook, enabling workaround\n"); + macbook = true; + return 0; +} + +static struct dmi_system_id acpi_smbus_dmi_table[] = { + { macbook_dmi_match, "Apple MacBook", { + DMI_MATCH(DMI_BOARD_VENDOR, "Apple"), + DMI_MATCH(DMI_PRODUCT_NAME, "MacBook") }, + }, + { }, +}; + static int acpi_smbus_hc_add(struct acpi_device *device) { int status; unsigned long long val; struct acpi_smb_hc *hc; + dmi_check_system(acpi_smbus_dmi_table); + if (!device) return -EINVAL; -- 2.20.1