[PATCH 2/2] x86/config/efi: drop DRIVER_SERIAL_NS16550

[Michael Olbrich]

On Tue, Oct 20, 2020 at 09:35:30AM +0200, Ahmad Fatoum wrote:
> On 10/20/20 9:26 AM, Uwe Kleine-König wrote:
> > On Tue, Oct 20, 2020 at 07:08:47AM +0200, Ahmad Fatoum wrote:
> >> Hello Uwe,
> >>
> >> On 9/18/20 1:04 PM, Uwe Kleine-König wrote:
> >>> For most machines having DRIVER_SERIAL_NS16550 and DRIVER_SERIAL_EFI_STDIO
> >>> both enabled results in the output appearing twice on the serial output.
> >>> So remove disable the lowlevel driver and rely on the EFI bios for serial.
> > 
> > How embarrassing, s/remove //.
> > 
> >> On the flip-side, some systems now won't output anything over serial with
> >> the defconfig, like the one I just ran into. Maybe we should keep both
> >> enabled, but have a quirk table, which boards to disable the 16550 for?
> > 
> > Expecting that most systems are happy with EFI_STDIO I would suggest a
> > quirk table for those systems which are not?!
> 
> Doubled output is better than no output, so a defconfig that
> by default displays anything if the BIOS is not in the quirk
> table sounds like it's the better choice?

Maybe disable CONSOLE_ACTIVATE_ALL instead? Then you should only get the
output from one driver.

Michael

> > 
> >> My board is
> >>   EFI v2.40 by American Megatrends v327691". What's yours?
> >>   barebox at barebox EFI payload:/ devinfo acpi-FACP0
> >>   [...]
> >>   Revision: 5
> >>   OemId: ALASKA
> >>   OemTableId: A M I
> >>   OemRevision: 17244169
> >>   CreatorId: 0x20494d41
> >>   CreatorRevision: 65555
> >>
> >> What's yours?
> > 
> > I saw the doubled output on my Laptop (Lenovo T460p).
> 
> You have serial output on your laptop?
> 
> > 
> > dmidecode has:
> > 
> > 	BIOS Information
> > 		Vendor: LENOVO
> > 		Version: R07ET81W (2.21 )
> > 		Release Date: 12/18/2017
> > 		Address: 0xE0000
> > 		Runtime Size: 128 kB
> > 		ROM Size: 16 MB
> > 		Characteristics:
> > 			PCI is supported
> > 			PNP is supported
> > 			BIOS is upgradeable
> > 			BIOS shadowing is allowed
> > 			Boot from CD is supported
> > 			Selectable boot is supported
> > 			EDD is supported
> > 			3.5"/720 kB floppy services are supported (int 13h)
> > 			Print screen service is supported (int 5h)
> > 			8042 keyboard services are supported (int 9h)
> > 			Serial services are supported (int 14h)
> > 			Printer services are supported (int 17h)
> > 			CGA/mono video services are supported (int 10h)
> > 			ACPI is supported
> > 			USB legacy is supported
> > 			BIOS boot specification is supported
> > 			Targeted content distribution is supported
> > 			UEFI is supported
> > 		BIOS Revision: 2.21
> > 		Firmware Revision: 1.4
> > 
> > (This is the system I write this mail on, I don't feel like rebooting to check
> > devinfo in barebox, take a picture and then type the stuff into a mail
> > by hand.)
> > 
> > Best regards
> > Uwe
> > 
> > 
> 
> -- 
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-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |