diff mbox series

[05/11] video/aperture: Only kick vgacon when the pdev is decoding vga

Message ID 20230111154112.90575-5-daniel.vetter@ffwll.ch
State New
Headers
Series [01/11] drm/ast: Use drm_aperture_remove_conflicting_pci_framebuffers |

Commit Message

Daniel Vetter Jan. 11, 2023, 3:41 p.m. UTC 
  Otherwise it's bit silly, and we might throw out the driver for the
screen the user is actually looking at. I haven't found a bug report
for this case yet, but we did get bug reports for the analog case
where we're throwing out the efifb driver.

References: https://bugzilla.kernel.org/show_bug.cgi?id=216303
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
---
 drivers/video/aperture.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Thomas Zimmermann Jan. 11, 2023, 4:03 p.m. UTC | #1 
Hi

Am 11.01.23 um 16:41 schrieb Daniel Vetter:
> Otherwise it's bit silly, and we might throw out the driver for the
> screen the user is actually looking at. I haven't found a bug report
> for this case yet, but we did get bug reports for the analog case
> where we're throwing out the efifb driver.
> 
> References: https://bugzilla.kernel.org/show_bug.cgi?id=216303
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Javier Martinez Canillas <javierm@redhat.com>
> Cc: Helge Deller <deller@gmx.de>
> Cc: linux-fbdev@vger.kernel.org
> ---
>   drivers/video/aperture.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
> index 3d8c925c7365..6f351a58f6c6 100644
> --- a/drivers/video/aperture.c
> +++ b/drivers/video/aperture.c
> @@ -341,6 +341,9 @@ int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *na
>   			return ret;
>   	}
>   
> +	if (!primary)
> +		return 0;
> +

The original code from fbdev didn't do this, so this code didn't either.

It appears more to be a special case than an early-out branch. So can we 
write it as

if (primary) {
   // kick_vgacon
}

?

Best regards
Thomas

>   	/*
>   	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
>   	 * otherwise the vga fbdev driver falls over.

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
Daniel Vetter Jan. 11, 2023, 4:55 p.m. UTC | #2 
On Wed, Jan 11, 2023 at 05:03:02PM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 11.01.23 um 16:41 schrieb Daniel Vetter:
> > Otherwise it's bit silly, and we might throw out the driver for the
> > screen the user is actually looking at. I haven't found a bug report
> > for this case yet, but we did get bug reports for the analog case
> > where we're throwing out the efifb driver.
> > 
> > References: https://bugzilla.kernel.org/show_bug.cgi?id=216303
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Javier Martinez Canillas <javierm@redhat.com>
> > Cc: Helge Deller <deller@gmx.de>
> > Cc: linux-fbdev@vger.kernel.org
> > ---
> >   drivers/video/aperture.c | 3 +++
> >   1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
> > index 3d8c925c7365..6f351a58f6c6 100644
> > --- a/drivers/video/aperture.c
> > +++ b/drivers/video/aperture.c
> > @@ -341,6 +341,9 @@ int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *na
> >   			return ret;
> >   	}
> > +	if (!primary)
> > +		return 0;
> > +
> 
> The original code from fbdev didn't do this, so this code didn't either.
> 
> It appears more to be a special case than an early-out branch. So can we
> write it as

Yeah I think this was a mistake going way back to when I added this to
i915 originally. It is a real change, but also I guess the people who have
machines without efifb or vesafb are ... really not many :-) Iirc you had
some very funny kernels going way back when vgacon was considered the only
safe choice to even hit this stuff.

> if (primary) {
>   // kick_vgacon
> }

Yeah, but next patch adds the vga aperture, and then I think it makes a
bit more sense.
-Daniel

> 
> ?
> 
> Best regards
> Thomas
> 
> >   	/*
> >   	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
> >   	 * otherwise the vga fbdev driver falls over.
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev
diff mbox series

Patch

diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
index 3d8c925c7365..6f351a58f6c6 100644
--- a/drivers/video/aperture.c
+++ b/drivers/video/aperture.c
@@ -341,6 +341,9 @@  int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *na
 			return ret;
 	}
 
+	if (!primary)
+		return 0;
+
 	/*
 	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
 	 * otherwise the vga fbdev driver falls over.