[PATCH] bochs-drm: disable video before changing video mode

[PATCH] bochs-drm: disable video before changing video mode

[Chris Ruffin]

qemu and simics simulators both seem to expect that video should be disabled
before changing the video mode.

references:
http://git.qemu.org/?p=qemu.git;a=blob;f=hw/display/vga.c;h=c0f7b343bbab586c8593d29c7a765f1e6ca3662c;hb=HEAD#l727
http://wiki.osdev.org/Bochs_VBE_Extensions#Setting_display_resolution_and_bit_depth

Signed-off-by: Chris Ruffin <chris.ruffin@intel.com>
---
 drivers/gpu/drm/bochs/bochs_hw.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/bochs/bochs_hw.c b/drivers/gpu/drm/bochs/bochs_hw.c
index 4603897..a39b034 100644
--- a/drivers/gpu/drm/bochs/bochs_hw.c
+++ b/drivers/gpu/drm/bochs/bochs_hw.c
@@ -164,6 +164,7 @@ void bochs_hw_setmode(struct bochs_device *bochs,
 
 	bochs_vga_writeb(bochs, 0x3c0, 0x20); /* unblank */
 
+	bochs_dispi_write(bochs, VBE_DISPI_INDEX_ENABLE,      0);
 	bochs_dispi_write(bochs, VBE_DISPI_INDEX_BPP,         bochs->bpp);
 	bochs_dispi_write(bochs, VBE_DISPI_INDEX_XRES,        bochs->xres);
 	bochs_dispi_write(bochs, VBE_DISPI_INDEX_YRES,        bochs->yres);
-- 
1.7.10.4

Re: [PATCH] bochs-drm: disable video before changing video mode

[Gerd Hoffmann]

On Mi, 2015-03-18 at 12:37 -0400, Chris Ruffin wrote:
> qemu and simics simulators both seem to expect that video should be disabled
> before changing the video mode.

Not required for qemu.  qemu allows updating the modesetting registers
(xres + friends) while vbe is enabled.

Turning it off, then back on after updating the registers doesn't hurt
though.  So if this change gets things going on simics it's fine with
me.

Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

cheers,
  Gerd

Re: [PATCH] bochs-drm: disable video before changing video mode

[Alexander Beregalov]

On 19 March 2015 at 11:26, Gerd Hoffmann <kraxel@redhat.com> wrote:
> On Mi, 2015-03-18 at 12:37 -0400, Chris Ruffin wrote:
>> qemu and simics simulators both seem to expect that video should be disabled
>> before changing the video mode.
>
> Not required for qemu.  qemu allows updating the modesetting registers
> (xres + friends) while vbe is enabled.
>
> Turning it off, then back on after updating the registers doesn't hurt
> though.  So if this change gets things going on simics it's fine with
> me.
>
> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

Hi Gerd, Dave,
I can't find the patch in linux-next,
will it be included in 4.1?

Re: [PATCH] bochs-drm: disable video before changing video mode

[David Airlie]

----- Original Message -----
> From: "Alexander Beregalov" <a.beregalov@gmail.com>
> To: "Gerd Hoffmann" <kraxel@redhat.com>
> Cc: "Chris Ruffin" <chris.ruffin@intel.com>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, "Dave
> Airlie" <airlied@redhat.com>, cmruffin@gmail.com, "Alexander Beregalov" <alexander.beregalov@intel.com>, "alexey
> buyanov" <alexey.buyanov@intel.com>
> Sent: Wednesday, 1 April, 2015 2:13:33 AM
> Subject: Re: [PATCH] bochs-drm: disable video before changing video mode
> 
> On 19 March 2015 at 11:26, Gerd Hoffmann <kraxel@redhat.com> wrote:
> > On Mi, 2015-03-18 at 12:37 -0400, Chris Ruffin wrote:
> >> qemu and simics simulators both seem to expect that video should be
> >> disabled
> >> before changing the video mode.
> >
> > Not required for qemu.  qemu allows updating the modesetting registers
> > (xres + friends) while vbe is enabled.
> >
> > Turning it off, then back on after updating the registers doesn't hurt
> > though.  So if this change gets things going on simics it's fine with
> > me.
> >
> > Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> Hi Gerd, Dave,
> I can't find the patch in linux-next,
> will it be included in 4.1?

Just added it now.

Thanks,
Dave.
>