linux-kernel - Re: [PATCH v3 5/5] ACPI / boot: Don't handle SCI on HW reduced platforms

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Date:   Sat, 22 Jul 2017 00:28:51 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-pm@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Hanjun Guo <guohanjun@...wei.com>,
        linux-acpi@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH v3 5/5] ACPI / boot: Don't handle SCI on HW reduced platforms

On Tuesday, July 18, 2017 06:04:20 PM Andy Shevchenko wrote:
> As per note in 5.2.9 Fixed ACPI Description Table (FADT) chapter of ACPI
> specification OSPM will ignore fields related to the ACPI HW register
> interface, one of which is SCI_INT.
> 
> Follow the spec and ignore any configuration done for interrupt line
> defined by SCI_INT if FADT specifies HW reduced platform.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Can we invalidate acpi_gbl_FADT.sci_interrupt somehow for
acpi_gbl_reduced_hardware?

The checks added below look somewhat arbitrary and it would be good to
provide some argumentation on why everything is covered by them as needed.

> ---
>  arch/x86/kernel/acpi/boot.c | 4 ++--
>  drivers/acpi/bus.c          | 2 +-
>  drivers/acpi/osl.c          | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 71c0feae60a4..c767efa53ee0 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -489,7 +489,7 @@ acpi_parse_int_src_ovr(struct acpi_subtable_header * header,
>  
>  	acpi_table_print_madt_entry(header);
>  
> -	if (intsrc->source_irq == acpi_gbl_FADT.sci_interrupt) {
> +	if (intsrc->source_irq == acpi_gbl_FADT.sci_interrupt && !acpi_gbl_reduced_hardware) {
>  		acpi_sci_ioapic_setup(intsrc->source_irq,
>  				      intsrc->inti_flags & ACPI_MADT_POLARITY_MASK,
>  				      (intsrc->inti_flags & ACPI_MADT_TRIGGER_MASK) >> 2,
> @@ -1184,7 +1184,7 @@ static int __init acpi_parse_madt_ioapic_entries(void)
>  	 * If BIOS did not supply an INT_SRC_OVR for the SCI
>  	 * pretend we got one so we can set the SCI flags.
>  	 */
> -	if (!acpi_sci_override_gsi)
> +	if (!acpi_sci_override_gsi && !acpi_gbl_reduced_hardware)
>  		acpi_sci_ioapic_setup(acpi_gbl_FADT.sci_interrupt, 0, 0,
>  				      acpi_gbl_FADT.sci_interrupt);
>  
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index af74b420ec83..1f3dde3bc8f8 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -1035,7 +1035,7 @@ void __init acpi_early_init(void)
>  	}
>  
>  #ifdef CONFIG_X86
> -	if (!acpi_ioapic) {
> +	if (!acpi_ioapic && !acpi_gbl_reduced_hardware) {
>  		/* compatible (0) means level (3) */
>  		if (!(acpi_sci_flags & ACPI_MADT_TRIGGER_MASK)) {
>  			acpi_sci_flags &= ~ACPI_MADT_TRIGGER_MASK;
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index db78d353bab1..4d84118a000b 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -553,7 +553,7 @@ acpi_os_install_interrupt_handler(u32 gsi, acpi_osd_handler handler,
>  	 * ACPI interrupts different from the SCI in our copy of the FADT are
>  	 * not supported.
>  	 */
> -	if (gsi != acpi_gbl_FADT.sci_interrupt)
> +	if (gsi != acpi_gbl_FADT.sci_interrupt || acpi_gbl_reduced_hardware)
>  		return AE_BAD_PARAMETER;
>  
>  	if (acpi_irq_handler)
>