On 23 April 2017 at 13:36, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> Commit 44be28e9dd98 ("x86/reboot: Add EFI reboot quirk for ACPI Hardware
> Reduced flag") sets pm_power_off to efi_power_off() when the
> acpi_gbl_reduced_hardware flag is set.
>
> According to its commit message this is necessary because: "BayTrail-T
> class of hardware requires EFI in order to powerdown and reboot and no
> other reliable method exists"
>
> But I have a Bay Trail CR tablet where the EFI_RESET_SHUTDOWN call does
> not work, it simply returns without doing anything (AFAICT).
>
> So it seems that some Bay Trail devices must use EFI for power-off, while
> for others only ACPI works.
>
> Note that efi_power_off() only gets used if the platform code defines
> efi_poweroff_required() and that returns true, this currently only ever
> happens on x86.
>
> Since on the devices which need ACPI for power-off the EFI_RESET_SHUTDOWN
> call simply returns, this patch makes the efi-reboot code remember the
> old pm_power_off handler and if EFI_RESET_SHUTDOWN returns it falls back
> to calling that.
>
> This seems preferable to dmi-quirking our way out of this, since there
> are likely quite a few devices suffering from this.
>
> Cc: Mark Salter <msalter@xxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/firmware/efi/reboot.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
> index 62ead9b..7117e2d 100644
> --- a/drivers/firmware/efi/reboot.c
> +++ b/drivers/firmware/efi/reboot.c
> @@ -5,6 +5,8 @@
> #include <linux/efi.h>
> #include <linux/reboot.h>
>
> +void (*orig_pm_power_off)(void);
> +
> int efi_reboot_quirk_mode = -1;
>
> void efi_reboot(enum reboot_mode reboot_mode, const char *__unused)
> @@ -51,6 +53,12 @@ bool __weak efi_poweroff_required(void)
> static void efi_power_off(void)
> {
> efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL);
> + /*
> + * The above call should not return, if it does fall back to
> + * the original power off method (typically ACPI poweroff).
> + */
> + if (orig_pm_power_off)
> + orig_pm_power_off();
> }
>
> static int __init efi_shutdown_init(void)
> @@ -58,8 +66,10 @@ static int __init efi_shutdown_init(void)
> if (!efi_enabled(EFI_RUNTIME_SERVICES))
> return -ENODEV;
>
> - if (efi_poweroff_required())
> + if (efi_poweroff_required()) {
> + orig_pm_power_off = pm_power_off;
> pm_power_off = efi_power_off;
> + }
>
> return 0;
> }
This does not look unreasonable to me, but this is more Matt's turf so
I will let him handle this one.
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
