ACPI: SPCR: Add support for DBG2 RISC-V SBI port subtype

[PATCH] ACPI: SPCR: Add support for DBG2 RISC-V SBI port subtype

Posted by cp0613@linux.alibaba.com 3 weeks, 1 day ago

From: Chen Pei <cp0613@linux.alibaba.com>

The commit 4aca2bef90bd1296 ("ACPICA: Headers: Add RISC-V SBI Subtype
to DBG2") has added the definition of ACPI_DBG2_RISCV_SBI_CON.

This patch continues to implement its function so that the parameters
of uart can be configured correctly. Subsequent calls to setup_earlycon
to reuse the earlycon based on sbi.

Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
---
 drivers/acpi/spcr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index cd36a97b0ea2..208d6bbc65e0 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -141,6 +141,9 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
 	case ACPI_DBG2_16550_NVIDIA:
 		uart = "uart";
 		break;
+	case ACPI_DBG2_RISCV_SBI_CON:
+		uart = "sbi";
+		break;
 	default:
 		err = -ENOENT;
 		goto done;
-- 
2.49.0

Re: [PATCH] ACPI: SPCR: Add support for DBG2 RISC-V SBI port subtype

Posted by Guo Ren 3 weeks ago

On Wed, Sep 10, 2025 at 5:42 PM <cp0613@linux.alibaba.com> wrote:
>
> From: Chen Pei <cp0613@linux.alibaba.com>
>
> The commit 4aca2bef90bd1296 ("ACPICA: Headers: Add RISC-V SBI Subtype
> to DBG2") has added the definition of ACPI_DBG2_RISCV_SBI_CON.
>
> This patch continues to implement its function so that the parameters
> of uart can be configured correctly. Subsequent calls to setup_earlycon
> to reuse the earlycon based on sbi.
>
> Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
> ---
>  drivers/acpi/spcr.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> index cd36a97b0ea2..208d6bbc65e0 100644
> --- a/drivers/acpi/spcr.c
> +++ b/drivers/acpi/spcr.c
> @@ -141,6 +141,9 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
>         case ACPI_DBG2_16550_NVIDIA:
>                 uart = "uart";
>                 break;
> +       case ACPI_DBG2_RISCV_SBI_CON:
> +               uart = "sbi";
> +               break;
Yes, SPCR lacks ACPI_DBG2_RISCV_SBI_CON, and ACPICA has adopted it.
So, it's time to add ACPI_DBG2_RISCV_SBI_CON support in spcr.c. It
would solve the UEFI + ACPI early debug problem.

LGTM!

Reviewed-by: Guo Ren (Alibaba Damo Academy) <guoren@kernel.org>

>         default:
>                 err = -ENOENT;
>                 goto done;
> --
> 2.49.0
>


-- 
Best Regards
 Guo Ren