Re: [PATCH] acpi: Avoid dropping rapid hotkey events (or other GPEs) on Asus EeePC

Alexey Starikovskiy
2008-07-17T11:49:58Z

Hi Alan,

Thanks for the patch, ACK.

Regards,
Alex.

Alan Jenkins wrote:
> It looks like this EC clears the SMI_EVT bit after every query, even if there
> are more events pending. The workaround is to repeatedly query the EC until
> it reports that no events remain.
>
> This fixes a regression in 2.6.26 (from 2.6.25.3). Initially reported as
> "Asus Eee PC hotkeys stop working if pressed quickly" in bugzilla
> <http://bugzilla.kernel.org/show_bug.cgi?id=11089>.
>
> The regression was caused by a recently added check for interrupt storms.
> The Eee PC triggers this check and switches to polling. When multiple events
> arrive between polling intervals, only one is fetched from the EC. This causes
> erroneous behaviour; ultimately events stop being delivered altogether when the
> EC buffer overflows.
>
> Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
>
> ---
> diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
> index 5622aee..2b4c5a2 100644
> --- a/drivers/acpi/ec.c
> +++ b/drivers/acpi/ec.c
> @@ -459,14 +459,10 @@ void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
>
> EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
>
> -static void acpi_ec_gpe_query(void *ec_cxt)
> +static void acpi_ec_gpe_run_handler(struct acpi_ec *ec, u8 value)
> {
> - struct acpi_ec *ec = ec_cxt;
> - u8 value = 0;
> struct acpi_ec_query_handler *handler, copy;
>
> - if (!ec || acpi_ec_query(ec, &value))
> - return;
> mutex_lock(&ec->lock);
> list_for_each_entry(handler, &ec->list, node) {
> if (value == handler->query_bit) {
> @@ -484,6 +480,18 @@ static void acpi_ec_gpe_query(void *ec_cxt)
> mutex_unlock(&ec->lock);
> }
>
> +static void acpi_ec_gpe_query(void *ec_cxt)
> +{
> + struct acpi_ec *ec = ec_cxt;
> + u8 value = 0;
> +
> + if (!ec)
> + return;
> +
> + while (!acpi_ec_query(ec, &value))
> + acpi_ec_gpe_run_handler(ec, value);
> +}
> +
> static u32 acpi_ec_gpe_handler(void *data)
> {
> acpi_status status = AE_OK;
>
>