On Wednesday, April 29, 2015 09:21:40 PM Chris Bainbridge wrote:
> 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>
Looks much better, I've queued it up as a fix for 4.1, thanks!
> ---
> 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;
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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