Regression in commit 7bc5a2bad0b8d9d1ac9f7b8b33150e4ddf197334
Author: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
Date: Sat Sep 20 13:19:47 2014 +0200
ACPI: Support _OSI("Darwin") correctly
Supporting _OSI("Darwin") 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 5us delay to the
start of each SMBUS transaction. This timing is the result of
experimentation - hangs were observed with 3us but never with 5us.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=94651
Signed-off-by: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>
---
drivers/acpi/sbshc.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/acpi/sbshc.c b/drivers/acpi/sbshc.c
index 26e5b50..bf034f8 100644
--- 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 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;
--
2.1.4
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