[PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Thomas Zimmermann]

Fix an off-by-one error when setting the vblanking start in
<VBLKSTR>. Commit d6460bd52c27 ("drm/mgag200: Add dedicated
variables for blanking fields") switched the value from
crtc_vdisplay to crtc_vblank_start, which DRM helpers copy
from the former. The commit missed to subtract one though.

Reported-by: Wakko Warner <wakko@animx.eu.org>
Closes: https://lore.kernel.org/dri-devel/CAMwc25rKPKooaSp85zDq2eh-9q4UPZD=RqSDBRp1fAagDnmRmA@mail.gmail.com/
Reported-by: Сергей <afmerlord@gmail.com>
Closes: https://lore.kernel.org/all/5b193b75-40b1-4342-a16a-ae9fc62f245a@gmail.com/
Closes: https://bbs.archlinux.org/viewtopic.php?id=303819
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: d6460bd52c27 ("drm/mgag200: Add dedicated variables for blanking fields")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.12+
---
 drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index fb71658c3117..6067d08aeee3 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -223,7 +223,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
 	vsyncstr = mode->crtc_vsync_start - 1;
 	vsyncend = mode->crtc_vsync_end - 1;
 	vtotal = mode->crtc_vtotal - 2;
-	vblkstr = mode->crtc_vblank_start;
+	vblkstr = mode->crtc_vblank_start - 1;
 	vblkend = vtotal + 1;
 
 	linecomp = vdispend;
-- 
2.49.0

Re: [PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Jocelyn Falempe]

On 16/04/2025 10:38, Thomas Zimmermann wrote:
> Fix an off-by-one error when setting the vblanking start in
> <VBLKSTR>. Commit d6460bd52c27 ("drm/mgag200: Add dedicated
> variables for blanking fields") switched the value from
> crtc_vdisplay to crtc_vblank_start, which DRM helpers copy
> from the former. The commit missed to subtract one though.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
> 
> Reported-by: Wakko Warner <wakko@animx.eu.org>
> Closes: https://lore.kernel.org/dri-devel/CAMwc25rKPKooaSp85zDq2eh-9q4UPZD=RqSDBRp1fAagDnmRmA@mail.gmail.com/
> Reported-by: Сергей <afmerlord@gmail.com>
> Closes: https://lore.kernel.org/all/5b193b75-40b1-4342-a16a-ae9fc62f245a@gmail.com/
> Closes: https://bbs.archlinux.org/viewtopic.php?id=303819
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Fixes: d6460bd52c27 ("drm/mgag200: Add dedicated variables for blanking fields")
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Jocelyn Falempe <jfalempe@redhat.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: <stable@vger.kernel.org> # v6.12+
> ---
>   drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index fb71658c3117..6067d08aeee3 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -223,7 +223,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
>   	vsyncstr = mode->crtc_vsync_start - 1;
>   	vsyncend = mode->crtc_vsync_end - 1;
>   	vtotal = mode->crtc_vtotal - 2;
> -	vblkstr = mode->crtc_vblank_start;
> +	vblkstr = mode->crtc_vblank_start - 1;
>   	vblkend = vtotal + 1;
>   
>   	linecomp = vdispend;

Re: [PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Wakko Warner]

Thomas Zimmermann wrote:
> Fix an off-by-one error when setting the vblanking start in
> <VBLKSTR>. Commit d6460bd52c27 ("drm/mgag200: Add dedicated
> variables for blanking fields") switched the value from
> crtc_vdisplay to crtc_vblank_start, which DRM helpers copy
> from the former. The commit missed to subtract one though.

Applied to 6.14.2.  BMC and external monitor works as expected.

Thank you.

> Reported-by: Wakko Warner <wakko@animx.eu.org>
> Closes: https://lore.kernel.org/dri-devel/CAMwc25rKPKooaSp85zDq2eh-9q4UPZD=RqSDBRp1fAagDnmRmA@mail.gmail.com/
> Reported-by: ???????????? <afmerlord@gmail.com>
> Closes: https://lore.kernel.org/all/5b193b75-40b1-4342-a16a-ae9fc62f245a@gmail.com/
> Closes: https://bbs.archlinux.org/viewtopic.php?id=303819
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Fixes: d6460bd52c27 ("drm/mgag200: Add dedicated variables for blanking fields")
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Jocelyn Falempe <jfalempe@redhat.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: <stable@vger.kernel.org> # v6.12+
> ---
>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index fb71658c3117..6067d08aeee3 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -223,7 +223,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
>  	vsyncstr = mode->crtc_vsync_start - 1;
>  	vsyncend = mode->crtc_vsync_end - 1;
>  	vtotal = mode->crtc_vtotal - 2;
> -	vblkstr = mode->crtc_vblank_start;
> +	vblkstr = mode->crtc_vblank_start - 1;
>  	vblkend = vtotal + 1;
>  
>  	linecomp = vdispend;
> -- 
> 2.49.0
> 
-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.

Re: [PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Thomas Zimmermann]

Hi

Am 16.04.25 um 17:22 schrieb Wakko Warner:
> Thomas Zimmermann wrote:
>> Fix an off-by-one error when setting the vblanking start in
>> <VBLKSTR>. Commit d6460bd52c27 ("drm/mgag200: Add dedicated
>> variables for blanking fields") switched the value from
>> crtc_vdisplay to crtc_vblank_start, which DRM helpers copy
>> from the former. The commit missed to subtract one though.
> Applied to 6.14.2.  BMC and external monitor works as expected.

Great. Thanks for testing. Can I add your Tested-by tag to the commit?

Best regards
Thomas

>
> Thank you.
>
>> Reported-by: Wakko Warner <wakko@animx.eu.org>
>> Closes: https://lore.kernel.org/dri-devel/CAMwc25rKPKooaSp85zDq2eh-9q4UPZD=RqSDBRp1fAagDnmRmA@mail.gmail.com/
>> Reported-by: ???????????? <afmerlord@gmail.com>
>> Closes: https://lore.kernel.org/all/5b193b75-40b1-4342-a16a-ae9fc62f245a@gmail.com/
>> Closes: https://bbs.archlinux.org/viewtopic.php?id=303819
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Fixes: d6460bd52c27 ("drm/mgag200: Add dedicated variables for blanking fields")
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Jocelyn Falempe <jfalempe@redhat.com>
>> Cc: Dave Airlie <airlied@redhat.com>
>> Cc: dri-devel@lists.freedesktop.org
>> Cc: <stable@vger.kernel.org> # v6.12+
>> ---
>>   drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> index fb71658c3117..6067d08aeee3 100644
>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> @@ -223,7 +223,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
>>   	vsyncstr = mode->crtc_vsync_start - 1;
>>   	vsyncend = mode->crtc_vsync_end - 1;
>>   	vtotal = mode->crtc_vtotal - 2;
>> -	vblkstr = mode->crtc_vblank_start;
>> +	vblkstr = mode->crtc_vblank_start - 1;
>>   	vblkend = vtotal + 1;
>>   
>>   	linecomp = vdispend;
>> -- 
>> 2.49.0
>>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

Re: [PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Wakko Warner]

Thomas Zimmermann wrote:
> Hi
> 
> Am 16.04.25 um 17:22 schrieb Wakko Warner:
> > Thomas Zimmermann wrote:
> > > Fix an off-by-one error when setting the vblanking start in
> > > <VBLKSTR>. Commit d6460bd52c27 ("drm/mgag200: Add dedicated
> > > variables for blanking fields") switched the value from
> > > crtc_vdisplay to crtc_vblank_start, which DRM helpers copy
> > > from the former. The commit missed to subtract one though.
> > Applied to 6.14.2.  BMC and external monitor works as expected.
> 
> Great. Thanks for testing. Can I add your Tested-by tag to the commit?

You may.

> > > Reported-by: Wakko Warner <wakko@animx.eu.org>
> > > Closes: https://lore.kernel.org/dri-devel/CAMwc25rKPKooaSp85zDq2eh-9q4UPZD=RqSDBRp1fAagDnmRmA@mail.gmail.com/
> > > Reported-by: ???????????? <afmerlord@gmail.com>
> > > Closes: https://lore.kernel.org/all/5b193b75-40b1-4342-a16a-ae9fc62f245a@gmail.com/
> > > Closes: https://bbs.archlinux.org/viewtopic.php?id=303819
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > > Fixes: d6460bd52c27 ("drm/mgag200: Add dedicated variables for blanking fields")
> > > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > > Cc: Jocelyn Falempe <jfalempe@redhat.com>
> > > Cc: Dave Airlie <airlied@redhat.com>
> > > Cc: dri-devel@lists.freedesktop.org
> > > Cc: <stable@vger.kernel.org> # v6.12+
> > > ---
> > >   drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > index fb71658c3117..6067d08aeee3 100644
> > > --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> > > @@ -223,7 +223,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
> > >   	vsyncstr = mode->crtc_vsync_start - 1;
> > >   	vsyncend = mode->crtc_vsync_end - 1;
> > >   	vtotal = mode->crtc_vtotal - 2;
> > > -	vblkstr = mode->crtc_vblank_start;
> > > +	vblkstr = mode->crtc_vblank_start - 1;
> > >   	vblkend = vtotal + 1;
> > >   	linecomp = vdispend;
> > > -- 
> > > 2.49.0
> > > 
> 
> -- 
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstrasse 146, 90461 Nuernberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
> HRB 36809 (AG Nuernberg)
> 
-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.

Re: [PATCH] drm/mgag200: Fix value in <VBLKSTR> register

[Сергей]

Hello. Maybe I don't understand something, but I installed kernel 
version 6.14.2 on Arch Linux and the problem with the blinking video 
signal on IPMI remained