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SubjectRe: [PATCH 1/8] arm64: move acpi/dt decision earlier in boot process
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On 22/02/16 14:46, Aleksey Makarov wrote:
> From: Leif Lindholm <leif.lindholm@linaro.org>
>
> In order to support selecting earlycon via either ACPI or DT, move
> the decision on whether to attempt ACPI configuration into the
> early_param handling. Then make acpi_boot_table_init() bail out if
> acpi_disabled.
>
> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
> arch/arm64/kernel/acpi.c | 54 ++++++++++++++++++++++++++----------------------
> 1 file changed, 29 insertions(+), 25 deletions(-)
>
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index d1ce8e2..7a944f7 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -44,6 +44,19 @@ EXPORT_SYMBOL(acpi_pci_disabled);
> static bool param_acpi_off __initdata;
> static bool param_acpi_force __initdata;
>
> +static int __init dt_scan_depth1_nodes(unsigned long node,
> + const char *uname, int depth,
> + void *data)
> +{
> + /*
> + * Return 1 as soon as we encounter a node at depth 1 that is
> + * not the /chosen node.
> + */
> + if (depth == 1 && (strcmp(uname, "chosen") != 0))
> + return 1;
> + return 0;
> +}
> +
> static int __init parse_acpi(char *arg)
> {
> if (!arg)
> @@ -57,23 +70,27 @@ static int __init parse_acpi(char *arg)
> else
> return -EINVAL; /* Core will print when we return error */
>
> - return 0;
> -}
> -early_param("acpi", parse_acpi);
> + /*
> + * Enable ACPI instead of device tree unless
> + * - ACPI has been disabled explicitly (acpi=off), or
> + * - the device tree is not empty (it has more than just a /chosen node)
> + * and ACPI has not been force enabled (acpi=force)
> + */
> + if (param_acpi_off ||
> + (!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
> + return 0;
>
> -static int __init dt_scan_depth1_nodes(unsigned long node,
> - const char *uname, int depth,
> - void *data)
> -{
> /*
> - * Return 1 as soon as we encounter a node at depth 1 that is
> - * not the /chosen node.
> + * ACPI is disabled at this point. Enable it in order to parse
> + * the ACPI tables and carry out sanity checks
> */
> - if (depth == 1 && (strcmp(uname, "chosen") != 0))
> - return 1;
> + enable_acpi();
> +

So we only enable ACPI if we pass acpi=force as kernel parameter?
I'm not sure if this is what you wanted to do.

Regards,
Matthias

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