This is a note to let you know that I've just added the patch titled
ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook
to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
acpi-sbs-add-5-us-delay-to-fix-sbs-hangs-on-macbook.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3349fb64b2927407017d970dd5c4daf3c5ad69f8 Mon Sep 17 00:00:00 2001
From: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>
Date: Wed, 29 Apr 2015 21:21:40 +0100
Subject: ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook
From: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>
commit 3349fb64b2927407017d970dd5c4daf3c5ad69f8 upstream.
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 <chris.bainbridge@xxxxxxxxx>
Cc: 3.18+ <stable@xxxxxxxxxxxxxxx> # 3.18+
[ rjw: Subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/acpi/sbshc.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
--- a/drivers/acpi/sbshc.c
+++ b/drivers/acpi/sbshc.c
@@ -14,6 +14,7 @@
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
+#include <linux/dmi.h>
#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
}
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(str
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;
Patches currently in stable-queue which might be from chris.bainbridge@xxxxxxxxx are
queue-4.0/acpi-sbs-add-5-us-delay-to-fix-sbs-hangs-on-macbook.patch
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