I've been told that BM_RLD is not a NOP in the PIIX4 - ICH4-M generations;
and that those chips follow the 1st description in the ACPI spec, not
the second. (I've also submitted a bug against the ACPI spec:-)
So the patch below is no good.
But the old code still isn't quite right.
It seems we should just set BM_RLD at initialization and forget about it
rather than monkeying with it at run-time.
cheers,
-Len
On Thursday 04 October 2007 00:53, Len Brown wrote:
> From: Len Brown <len.brown@xxxxxxxxx>
>
> The ACPI specification describes PM1*_CNT_BLK.BM_RLD in two places.
>
> The first description says that the OS needs to set BM_RLD
> to enable bus master activity to wake the processor from C3.
>
> The second description says that the platform sets BM_RLD
> to indicate whether it was bus master activity that woke the
> platform from C3 or not.
>
> The first description is erroneous, the second description is correct.
> Delete Linux's implementation of the first description.
>
> Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index f182613..4f004f1 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -192,26 +192,6 @@ acpi_processor_power_activate(struct acpi_processor *pr,
> old->promotion.count = 0;
> new->demotion.count = 0;
>
> - /* Cleanup from old state. */
> - if (old) {
> - switch (old->type) {
> - case ACPI_STATE_C3:
> - /* Disable bus master reload */
> - if (new->type != ACPI_STATE_C3 && pr->flags.bm_check)
> - acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
> - break;
> - }
> - }
> -
> - /* Prepare to use new state. */
> - switch (new->type) {
> - case ACPI_STATE_C3:
> - /* Enable bus master reload */
> - if (old->type != ACPI_STATE_C3 && pr->flags.bm_check)
> - acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
> - break;
> - }
> -
> pr->power.state = new;
>
> return;
> @@ -1027,7 +1007,6 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
> " for C3 to be enabled on SMP systems\n"));
> return;
> }
> - acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
> }
>
> /*
>
-
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