Re: [PATCH v2 1/1] RISC-V: ACPI: Enable SPCR table for console output on RISC-V

Sunil V L
2024-07-09T04:50:13Z

On Thu, May 02, 2024 at 12:37:51AM -0700, Sia Jee Heng wrote:
> The ACPI SPCR code has been used to enable console output for ARM64 and
> X86. The same code can be reused for RISC-V. Furthermore, SPCR table is
> mandated for headless system as outlined in the RISC-V BRS
> Specification, chapter 6.
>
> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/kernel/acpi.c | 12 +++++++++++-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index be09c8836d56..ff2e270bbe01 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -14,6 +14,7 @@ config RISCV
> def_bool y
> select ACPI_GENERIC_GSI if ACPI
> select ACPI_REDUCED_HARDWARE_ONLY if ACPI
> + select ACPI_SPCR_TABLE if ACPI
> select ARCH_DMA_DEFAULT_COHERENT
> select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
> select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index e619edc8b0cc..43a12c00ae8b 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -17,7 +17,9 @@
> #include <linux/efi.h>
> #include <linux/io.h>
> #include <linux/memblock.h>
> +#include <linux/of_fdt.h>
> #include <linux/pci.h>
> +#include <linux/serial_core.h>
>
> int acpi_noirq = 1; /* skip ACPI IRQ initialization */
> int acpi_disabled = 1;
> @@ -131,7 +133,7 @@ void __init acpi_boot_table_init(void)
> if (param_acpi_off ||
> (!param_acpi_on && !param_acpi_force &&
> efi.acpi20 == EFI_INVALID_TABLE_ADDR))
> - return;
> + goto done;
>
> /*
> * ACPI is disabled at this point. Enable it in order to parse
> @@ -151,6 +153,14 @@ void __init acpi_boot_table_init(void)
> if (!param_acpi_force)
> disable_acpi();
> }
> +
> +done:
> + if (acpi_disabled) {
> + if (earlycon_acpi_spcr_enable)
> + early_init_dt_scan_chosen_stdout();
> + } else {
> + acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
> + }
LGTM.

Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>

Thanks,
Sunil
> }
>
> static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, const unsigned long end)
> --
> 2.34.1
>