[1/4] vgacon: rework Kconfig dependencies

Commit Message

Arnd Bergmann July 7, 2023, 9:52 a.m. UTC

From: Arnd Bergmann <[e-mail]>

The list of dependencies here is phrased as an opt-out, but this is missing
a lot of architectures that don't actually support VGA consoles, and some
of the entries are stale:

 - powerpc used to support VGA consoles in the old arch/ppc codebase, but
   the merged arch/powerpc never did

 - arm lists footbridge, integrator and netwinder, but netwinder is actually
   part of footbridge, and integrator does not appear to have an actual
   VGA hardware, or list it in its ATAG or DT.

 - mips has a few platforms (jazz, sibyte, and sni) that initialize
   screen_info, on everything else the console is selected but cannot
   actually work.

 - csky, hexgagon, loongarch, nios2, riscv and xtensa are not listed
   in the opt-out table and declare a screen_info to allow building
   vga_con, but this cannot work because the console is never selected.

Replace this with an opt-in table that lists only the platforms that
remain. This is effectively x86, plus a couple of historic workstation
and server machines that reused parts of the x86 system architecture.

Signed-off-by: Arnd Bergmann <[e-mail]>
---
 drivers/video/console/Kconfig | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Javier Martinez Canillas July 7, 2023, 1:17 p.m. UTC | #1

Arnd Bergmann <[e-mail]> writes:

Hello Arnd,

> From: Arnd Bergmann <[e-mail]>
>
> The list of dependencies here is phrased as an opt-out, but this is missing
> a lot of architectures that don't actually support VGA consoles, and some
> of the entries are stale:
>
>  - powerpc used to support VGA consoles in the old arch/ppc codebase, but
>    the merged arch/powerpc never did
>
>  - arm lists footbridge, integrator and netwinder, but netwinder is actually
>    part of footbridge, and integrator does not appear to have an actual
>    VGA hardware, or list it in its ATAG or DT.
>
>  - mips has a few platforms (jazz, sibyte, and sni) that initialize
>    screen_info, on everything else the console is selected but cannot
>    actually work.
>
>  - csky, hexgagon, loongarch, nios2, riscv and xtensa are not listed
>    in the opt-out table and declare a screen_info to allow building
>    vga_con, but this cannot work because the console is never selected.
>
> Replace this with an opt-in table that lists only the platforms that
> remain. This is effectively x86, plus a couple of historic workstation
> and server machines that reused parts of the x86 system architecture.
>
> Signed-off-by: Arnd Bergmann <[e-mail]>
> ---

Both our explanation and changes look good to me.

Reviewed-by: Javier Martinez Canillas <[e-mail]>

Thomas Zimmermann July 7, 2023, 3:07 p.m. UTC | #2

Hi,

for the whole series:

Reviewed-by: Thomas Zimmermann <[e-mail]>

Best regards
Thomas

Am 07.07.23 um 11:52 schrieb Arnd Bergmann:
> From: Arnd Bergmann <[e-mail]>
> 
> The list of dependencies here is phrased as an opt-out, but this is missing
> a lot of architectures that don't actually support VGA consoles, and some
> of the entries are stale:
> 
>   - powerpc used to support VGA consoles in the old arch/ppc codebase, but
>     the merged arch/powerpc never did
> 
>   - arm lists footbridge, integrator and netwinder, but netwinder is actually
>     part of footbridge, and integrator does not appear to have an actual
>     VGA hardware, or list it in its ATAG or DT.
> 
>   - mips has a few platforms (jazz, sibyte, and sni) that initialize
>     screen_info, on everything else the console is selected but cannot
>     actually work.
> 
>   - csky, hexgagon, loongarch, nios2, riscv and xtensa are not listed
>     in the opt-out table and declare a screen_info to allow building
>     vga_con, but this cannot work because the console is never selected.
> 
> Replace this with an opt-in table that lists only the platforms that
> remain. This is effectively x86, plus a couple of historic workstation
> and server machines that reused parts of the x86 system architecture.
> 
> Signed-off-by: Arnd Bergmann <[e-mail]>
> ---
>   drivers/video/console/Kconfig | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
> index a2a88d42edf0c..47c498defc211 100644
> --- a/drivers/video/console/Kconfig
> +++ b/drivers/video/console/Kconfig
> @@ -7,9 +7,9 @@ menu "Console display driver support"
>   
>   config VGA_CONSOLE
>   	bool "VGA text console" if EXPERT || !X86
> -	depends on !4xx && !PPC_8xx && !SPARC && !M68K && !PARISC &&  !SUPERH && \
> -		(!ARM || ARCH_FOOTBRIDGE || ARCH_INTEGRATOR || ARCH_NETWINDER) && \
> -		!ARM64 && !ARC && !MICROBLAZE && !OPENRISC && !S390 && !UML
> +	depends on ALPHA || IA64 || X86 || \
> +		(ARM && ARCH_FOOTBRIDGE) || \
> +		(MIPS && (MIPS_MALTA || SIBYTE_BCM112X || SIBYTE_SB1250 || SIBYTE_BCM1x80 || SNI_RM))
>   	select APERTURE_HELPERS if (DRM || FB || VFIO_PCI_CORE)
>   	default y
>   	help

Thomas Zimmermann Aug. 1, 2023, 4:55 p.m. UTC | #3

ping! What's the status of this patchset?

Am 07.07.23 um 11:52 schrieb Arnd Bergmann:
> From: Arnd Bergmann <[e-mail]>
> 
> The list of dependencies here is phrased as an opt-out, but this is missing
> a lot of architectures that don't actually support VGA consoles, and some
> of the entries are stale:
> 
>   - powerpc used to support VGA consoles in the old arch/ppc codebase, but
>     the merged arch/powerpc never did
> 
>   - arm lists footbridge, integrator and netwinder, but netwinder is actually
>     part of footbridge, and integrator does not appear to have an actual
>     VGA hardware, or list it in its ATAG or DT.
> 
>   - mips has a few platforms (jazz, sibyte, and sni) that initialize
>     screen_info, on everything else the console is selected but cannot
>     actually work.
> 
>   - csky, hexgagon, loongarch, nios2, riscv and xtensa are not listed
>     in the opt-out table and declare a screen_info to allow building
>     vga_con, but this cannot work because the console is never selected.
> 
> Replace this with an opt-in table that lists only the platforms that
> remain. This is effectively x86, plus a couple of historic workstation
> and server machines that reused parts of the x86 system architecture.
> 
> Signed-off-by: Arnd Bergmann <[e-mail]>
> ---
>   drivers/video/console/Kconfig | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
> index a2a88d42edf0c..47c498defc211 100644
> --- a/drivers/video/console/Kconfig
> +++ b/drivers/video/console/Kconfig
> @@ -7,9 +7,9 @@ menu "Console display driver support"
>   
>   config VGA_CONSOLE
>   	bool "VGA text console" if EXPERT || !X86
> -	depends on !4xx && !PPC_8xx && !SPARC && !M68K && !PARISC &&  !SUPERH && \
> -		(!ARM || ARCH_FOOTBRIDGE || ARCH_INTEGRATOR || ARCH_NETWINDER) && \
> -		!ARM64 && !ARC && !MICROBLAZE && !OPENRISC && !S390 && !UML
> +	depends on ALPHA || IA64 || X86 || \
> +		(ARM && ARCH_FOOTBRIDGE) || \
> +		(MIPS && (MIPS_MALTA || SIBYTE_BCM112X || SIBYTE_SB1250 || SIBYTE_BCM1x80 || SNI_RM))
>   	select APERTURE_HELPERS if (DRM || FB || VFIO_PCI_CORE)
>   	default y
>   	help

Russell King (Oracle) Aug. 1, 2023, 5:05 p.m. UTC | #4

On Fri, Jul 07, 2023 at 11:52:23AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[e-mail]>
> 
> The list of dependencies here is phrased as an opt-out, but this is missing
> a lot of architectures that don't actually support VGA consoles, and some
> of the entries are stale:
> 
>  - powerpc used to support VGA consoles in the old arch/ppc codebase, but
>    the merged arch/powerpc never did
> 
>  - arm lists footbridge, integrator and netwinder, but netwinder is actually
>    part of footbridge, and integrator does not appear to have an actual
>    VGA hardware, or list it in its ATAG or DT.

Integrator/AP has PCI, and I have had PCI VGA cards plugged in to that
hardware when I've had it.

Provided any platform sets up PCI in a compatible way, and can run the
VGA's BIOS to initialise the card, then vgacon is supportable.

Arnd Bergmann Aug. 4, 2023, 8:55 p.m. UTC | #5

On Tue, Aug 1, 2023, at 19:05, Russell King (Oracle) wrote:
> On Fri, Jul 07, 2023 at 11:52:23AM +0200, Arnd Bergmann wrote:
>> From: Arnd Bergmann <[e-mail]>
>> 
>> The list of dependencies here is phrased as an opt-out, but this is missing
>> a lot of architectures that don't actually support VGA consoles, and some
>> of the entries are stale:
>> 
>>  - powerpc used to support VGA consoles in the old arch/ppc codebase, but
>>    the merged arch/powerpc never did
>> 
>>  - arm lists footbridge, integrator and netwinder, but netwinder is actually
>>    part of footbridge, and integrator does not appear to have an actual
>>    VGA hardware, or list it in its ATAG or DT.
>
> Integrator/AP has PCI, and I have had PCI VGA cards plugged in to that
> hardware when I've had it.

I'm pretty sure it can no longer work and broke a while ago,
so I would prefer to leave it out unless someone actually has
a reason to use it and puts the work in to restore the support.
From what I can tell, it's broken in at least three ways with
the new PCI host driver:

- the PCI memory space is identity mapped to its CPU physical
  address as of d3721efce22d1 ("ARM: dts: integratorap: Fix
  PCI windows"), which is generally better for compatibility
  with broken drivers that read the BAR directly, but it
  prevents memory mapped ISA-style devices including VGA text
  buffer.

- vga_base is no longer set by the new PCI host driver, so
  any accesses to the text buffer just end up in user space
  memory at (__iomem*)0xb8000

- there is no DT binding for setting the global screen_info
  to whatever the boot firmware has initialized
  the VGA BIOS to, and the default 80x30 on Arm does not match
  the typical 80x25 text that would be set by the BIOS.

> Provided any platform sets up PCI in a compatible way, and can run the
> VGA's BIOS to initialise the card, then vgacon is supportable.

It looks like only footbridge does at this point, all the other
platforms would need to fix at least some of the three things I
mentioned above, in particular plat-orion is the only thing
setting vga_base but also has the identity map issue.

My impression is that nobody has cared about vgacon on most
Arm systems since it's harder to get working than fbcon with
a native PCI driver (or the built-in pl110 on integrator) but
also less useful.

    Arnd

Patch

diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
index a2a88d42edf0c..47c498defc211 100644
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig
@@ -7,9 +7,9 @@  menu "Console display driver support"
 
 config VGA_CONSOLE
 	bool "VGA text console" if EXPERT || !X86
-	depends on !4xx && !PPC_8xx && !SPARC && !M68K && !PARISC &&  !SUPERH && \
-		(!ARM || ARCH_FOOTBRIDGE || ARCH_INTEGRATOR || ARCH_NETWINDER) && \
-		!ARM64 && !ARC && !MICROBLAZE && !OPENRISC && !S390 && !UML
+	depends on ALPHA || IA64 || X86 || \
+		(ARM && ARCH_FOOTBRIDGE) || \
+		(MIPS && (MIPS_MALTA || SIBYTE_BCM112X || SIBYTE_SB1250 || SIBYTE_BCM1x80 || SNI_RM))
 	select APERTURE_HELPERS if (DRM || FB || VFIO_PCI_CORE)
 	default y
 	help