Hi Desapogu, On Wed, 29 Jul 2026 at 21:43, Desapogu Jayaramudu <[email protected]> wrote: > > U-Boot running as a coreboot payload obtains serial console > information either from the coreboot table or from the ACPI DBG2 > table. > > When serial console support is disabled in coreboot, the coreboot > table does not contain serial information. In this case U-Boot falls > back to parsing the DBG2 table. > > Some AMD platforms or any other platforms that uses memory-mapped I/O > advertise the debug UART using DBG2 subtype 0x0012 ("16550-compatible > with parameters defined in Generic Address Structure"). U-Boot > currently accepts only subtype 0x0000, causing DBG2 UART detection to > fail and leaving no console output. > > Accept subtype 0x0012 as well and keep the existing handling logic. > > Signed-off-by: Desapogu Jayaramudu <[email protected]> > --- > v5: > - removed whitespce > > drivers/serial/serial_coreboot.c | 3 ++- > include/acpi/acpi_table.h | 1 + > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/serial/serial_coreboot.c > b/drivers/serial/serial_coreboot.c > index b1f69f6998cfa1..89da11ffa5241e 100644 > --- a/drivers/serial/serial_coreboot.c > +++ b/drivers/serial/serial_coreboot.c > @@ -59,7 +59,8 @@ static int read_dbg2(struct ns16550_plat *plat) > log_debug("Not a serial port\n"); > return -EPROTOTYPE; > } > - if (dbg->port_subtype != ACPI_DBG2_16550_COMPATIBLE) { > + if (dbg->port_subtype != ACPI_DBG2_16550_COMPATIBLE && > + dbg->port_subtype != ACPI_DBG2_16550_WITH_GAS) { > log_debug("Incompatible serial port\n"); > return -EPROTOTYPE; > } > diff --git a/include/acpi/acpi_table.h b/include/acpi/acpi_table.h > index 4895366a6188ec..ac50ea10312e28 100644 > --- a/include/acpi/acpi_table.h > +++ b/include/acpi/acpi_table.h > @@ -674,6 +674,7 @@ struct __packed acpi_dmar { > #define ACPI_DBG2_ARM_SBSA_GENERIC 0x000E > #define ACPI_DBG2_ARM_DCC 0x000F > #define ACPI_DBG2_BCM2835 0x0010 > +#define ACPI_DBG2_16550_WITH_GAS 0x0012 /* 16550-compatible UART with > GAS */ > > #define ACPI_DBG2_1394_STANDARD 0x0000 > > -- > 2.43.0 >
I added my review tag to v4 - the idea is that you collect that tag and send it out with the next version, unless you make major changes etc. Here it is again: Reviewed-by: Simon Glass <[email protected]> Note that you don't need to send a v6 with this tag, since patchwork will pick it up - you only need to collect the tag (e.g. manually, or with 'patman series gather') when you need to send a new version with changes. You probably already know this, sorry if so :-) Regards, Simon
