Re: [PATCH] term/serial: Continue processing SPCR table even if revision is < 2

[Benjamin Herrenschmidt]

On Wed, 2023-07-26 at 16:02 -0500, Glenn Washburn wrote:
> According to commit 0231d00082 ("ACPI: SPCR: Make SPCR available to
> x86")
> to the Linux kernel, "On x86, many systems have a valid SPCR table
> but the
> table version is not 2 so the table version check must be a warning."
> 
> Signed-off-by: Glenn Washburn <development@efficientek.com>

Reviewd-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Note: We should also start using the new UART clock field when
available (rev 3 or later) and precise baud rate (rev 4)

Cheers,
Ben.

> ---
>  grub-core/term/ns8250-spcr.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/grub-core/term/ns8250-spcr.c b/grub-core/term/ns8250-
> spcr.c
> index d101bffb512d..d52b52c26561 100644
> --- a/grub-core/term/ns8250-spcr.c
> +++ b/grub-core/term/ns8250-spcr.c
> @@ -18,6 +18,7 @@
>  
>  #if !defined(GRUB_MACHINE_IEEE1275) && !defined(GRUB_MACHINE_QEMU)
>  
> +#include <grub/misc.h>
>  #include <grub/serial.h>
>  #include <grub/ns8250.h>
>  #include <grub/types.h>
> @@ -34,7 +35,8 @@ grub_ns8250_spcr_init (void)
>    if (spcr == NULL)
>      return NULL;
>    if (spcr->hdr.revision < 2)
> -    return NULL;
> +    grub_dprintf ("serial", "SPCR table revision %d < 2, continuing
> anyway\n",
> +                 (int) spcr->hdr.revision);
>    if (spcr->intf_type != GRUB_ACPI_SPCR_INTF_TYPE_16550 &&
>        spcr->intf_type != GRUB_ACPI_SPCR_INTF_TYPE_16550X)
>      return NULL;