[PATCH] drm/msm: enable separate_gpu_kms by default

[PATCH] drm/msm: enable separate_gpu_kms by default

[Mahadevan P]

On targets with multiple display subsystems, such as SA8775P, the GPU
binds to the first display subsystem that probes. This implicit binding
prevents subsequent display subsystems from probing successfully,
breaking multi-display support.

Enable separate_gpu_kms by default to decouple GPU and display subsystem
probing. This allows each display subsystem to initialize independently,
ensuring that all display subsystems are probed.

Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
---
Depends on:
	https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
	https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
---
 drivers/gpu/drm/msm/msm_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index ed2a61c66ac9..65119fb3dfa2 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -54,7 +54,7 @@ static bool modeset = true;
 MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
 module_param(modeset, bool, 0600);
 
-static bool separate_gpu_kms;
+static bool separate_gpu_kms = true;
 MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
 module_param(separate_gpu_kms, bool, 0400);
 

---
base-commit: 50f68cc7be0a2cbf54d8f6aaf17df32fb01acc3f
change-id: 20260219-seperate_gpu_kms-97870cb36aaf

Best regards,
-- 
Mahadevan P <mahadevan.p@oss.qualcomm.com>

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Dmitry Baryshkov]

On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> On targets with multiple display subsystems, such as SA8775P, the GPU
> binds to the first display subsystem that probes. This implicit binding
> prevents subsequent display subsystems from probing successfully,
> breaking multi-display support.
> 
> Enable separate_gpu_kms by default to decouple GPU and display subsystem
> probing. This allows each display subsystem to initialize independently,
> ensuring that all display subsystems are probed.
> 
> Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> ---
> Depends on:
> 	https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> 	https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/

What exactly depends on this patchset?

> ---
>  drivers/gpu/drm/msm/msm_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index ed2a61c66ac9..65119fb3dfa2 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -54,7 +54,7 @@ static bool modeset = true;
>  MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
>  module_param(modeset, bool, 0600);
>  
> -static bool separate_gpu_kms;
> +static bool separate_gpu_kms = true;
>  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
>  module_param(separate_gpu_kms, bool, 0400);

The patch LGTM, but I'd prefer to get confirmation from Rob.

BTW: have you tested it with X11? Are you still getting accelerated GPU?

-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Mahadevan P]

On 2/23/2026 2:02 AM, Dmitry Baryshkov wrote:
> On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
>> On targets with multiple display subsystems, such as SA8775P, the GPU
>> binds to the first display subsystem that probes. This implicit binding
>> prevents subsequent display subsystems from probing successfully,
>> breaking multi-display support.
>>
>> Enable separate_gpu_kms by default to decouple GPU and display subsystem
>> probing. This allows each display subsystem to initialize independently,
>> ensuring that all display subsystems are probed.
>>
>> Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
>> ---
>> Depends on:
	[1]
>> 	https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
	[2]
>> 	https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
> 
> What exactly depends on this patchset?
The dependency is as follows:
As we separate out module loading of adreno and mdss with 
separate_gpu_kms=1 autoloading of msm.ko fails. With change [1] on 
bootup, msm.ko is loaded and gpu card is created.

The main reason to bring this patch here in upstream is for enabling of 
dual dpu configuration in Lemans hence added [2] as dependency.

> 
>> ---
>>   drivers/gpu/drm/msm/msm_drv.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
>> index ed2a61c66ac9..65119fb3dfa2 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.c
>> +++ b/drivers/gpu/drm/msm/msm_drv.c
>> @@ -54,7 +54,7 @@ static bool modeset = true;
>>   MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
>>   module_param(modeset, bool, 0600);
>>   
>> -static bool separate_gpu_kms;
>> +static bool separate_gpu_kms = true;
>>   MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
>>   module_param(separate_gpu_kms, bool, 0400);
> 
> The patch LGTM, but I'd prefer to get confirmation from Rob.
> 
> BTW: have you tested it with X11? Are you still getting accelerated GPU?

Yes, tested today with X11 app(xterm), GPU rendering is used.
> 

Thanks,
Mahadevan

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Dmitry Baryshkov]

On Wed, Feb 25, 2026 at 02:58:49PM +0530, Mahadevan P wrote:
> 
> 
> On 2/23/2026 2:02 AM, Dmitry Baryshkov wrote:
> > On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> > > On targets with multiple display subsystems, such as SA8775P, the GPU
> > > binds to the first display subsystem that probes. This implicit binding
> > > prevents subsequent display subsystems from probing successfully,
> > > breaking multi-display support.
> > > 
> > > Enable separate_gpu_kms by default to decouple GPU and display subsystem
> > > probing. This allows each display subsystem to initialize independently,
> > > ensuring that all display subsystems are probed.
> > > 
> > > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> > > ---
> > > Depends on:
> 	[1]
> > > 	https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> 	[2]
> > > 	https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
> > 
> > What exactly depends on this patchset?
> The dependency is as follows:
> As we separate out module loading of adreno and mdss with separate_gpu_kms=1
> autoloading of msm.ko fails. With change [1] on bootup, msm.ko is loaded and
> gpu card is created.
> 
> The main reason to bring this patch here in upstream is for enabling of dual
> dpu configuration in Lemans hence added [2] as dependency.

None of that describes why they are dependencies (i.e. must be applied
_before_ this patch, which otherwise will be broken).

> 
> > 
> > > ---
> > >   drivers/gpu/drm/msm/msm_drv.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > > index ed2a61c66ac9..65119fb3dfa2 100644
> > > --- a/drivers/gpu/drm/msm/msm_drv.c
> > > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > > @@ -54,7 +54,7 @@ static bool modeset = true;
> > >   MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
> > >   module_param(modeset, bool, 0600);
> > > -static bool separate_gpu_kms;
> > > +static bool separate_gpu_kms = true;
> > >   MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
> > >   module_param(separate_gpu_kms, bool, 0400);
> > 
> > The patch LGTM, but I'd prefer to get confirmation from Rob.
> > 
> > BTW: have you tested it with X11? Are you still getting accelerated GPU?
> 
> Yes, tested today with X11 app(xterm), GPU rendering is used.
> > 
> 
> Thanks,
> Mahadevan

-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Rob Clark]

On Sun, Feb 22, 2026 at 12:32 PM Dmitry Baryshkov
<dmitry.baryshkov@oss.qualcomm.com> wrote:
>
> On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> > On targets with multiple display subsystems, such as SA8775P, the GPU
> > binds to the first display subsystem that probes. This implicit binding
> > prevents subsequent display subsystems from probing successfully,
> > breaking multi-display support.
> >
> > Enable separate_gpu_kms by default to decouple GPU and display subsystem
> > probing. This allows each display subsystem to initialize independently,
> > ensuring that all display subsystems are probed.
> >
> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> > ---
> > Depends on:
> >       https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> >       https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
>
> What exactly depends on this patchset?
>
> > ---
> >  drivers/gpu/drm/msm/msm_drv.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > index ed2a61c66ac9..65119fb3dfa2 100644
> > --- a/drivers/gpu/drm/msm/msm_drv.c
> > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > @@ -54,7 +54,7 @@ static bool modeset = true;
> >  MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
> >  module_param(modeset, bool, 0600);
> >
> > -static bool separate_gpu_kms;
> > +static bool separate_gpu_kms = true;
> >  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
> >  module_param(separate_gpu_kms, bool, 0400);
>
> The patch LGTM, but I'd prefer to get confirmation from Rob.

I prefer to be a bit more paranoid.. perhaps switch this to a tri-state:

 -1: separate drm devices if there is more than one dpu or gpu,
     otherwise, single combined drm device [default]
  0: single drm device (matching up pairs of dpu and gpu if needed)
  1: separate drm devices

This way we aren't changing (or breaking) things for existing users.

BR,
-R

> BTW: have you tested it with X11? Are you still getting accelerated GPU?
>
> --
> With best wishes
> Dmitry

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Dmitry Baryshkov]

On Tue, Mar 03, 2026 at 10:35:46AM -0800, Rob Clark wrote:
> On Sun, Feb 22, 2026 at 12:32 PM Dmitry Baryshkov
> <dmitry.baryshkov@oss.qualcomm.com> wrote:
> >
> > On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> > > On targets with multiple display subsystems, such as SA8775P, the GPU
> > > binds to the first display subsystem that probes. This implicit binding
> > > prevents subsequent display subsystems from probing successfully,
> > > breaking multi-display support.
> > >
> > > Enable separate_gpu_kms by default to decouple GPU and display subsystem
> > > probing. This allows each display subsystem to initialize independently,
> > > ensuring that all display subsystems are probed.
> > >
> > > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> > > ---
> > > Depends on:
> > >       https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> > >       https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
> >
> > What exactly depends on this patchset?
> >
> > > ---
> > >  drivers/gpu/drm/msm/msm_drv.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > > index ed2a61c66ac9..65119fb3dfa2 100644
> > > --- a/drivers/gpu/drm/msm/msm_drv.c
> > > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > > @@ -54,7 +54,7 @@ static bool modeset = true;
> > >  MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
> > >  module_param(modeset, bool, 0600);
> > >
> > > -static bool separate_gpu_kms;
> > > +static bool separate_gpu_kms = true;
> > >  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
> > >  module_param(separate_gpu_kms, bool, 0400);
> >
> > The patch LGTM, but I'd prefer to get confirmation from Rob.
> 
> I prefer to be a bit more paranoid.. perhaps switch this to a tri-state:
> 
>  -1: separate drm devices if there is more than one dpu or gpu,
>      otherwise, single combined drm device [default]
>   0: single drm device (matching up pairs of dpu and gpu if needed)
>   1: separate drm devices
> 
> This way we aren't changing (or breaking) things for existing users.

I'd rather break things and hear about them being broken.

> 
> BR,
> -R
> 
> > BTW: have you tested it with X11? Are you still getting accelerated GPU?
> >
> > --
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Rob Clark]

On Tue, Mar 3, 2026 at 2:32 PM Dmitry Baryshkov
<dmitry.baryshkov@oss.qualcomm.com> wrote:
>
> On Tue, Mar 03, 2026 at 10:35:46AM -0800, Rob Clark wrote:
> > On Sun, Feb 22, 2026 at 12:32 PM Dmitry Baryshkov
> > <dmitry.baryshkov@oss.qualcomm.com> wrote:
> > >
> > > On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> > > > On targets with multiple display subsystems, such as SA8775P, the GPU
> > > > binds to the first display subsystem that probes. This implicit binding
> > > > prevents subsequent display subsystems from probing successfully,
> > > > breaking multi-display support.
> > > >
> > > > Enable separate_gpu_kms by default to decouple GPU and display subsystem
> > > > probing. This allows each display subsystem to initialize independently,
> > > > ensuring that all display subsystems are probed.
> > > >
> > > > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> > > > ---
> > > > Depends on:
> > > >       https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> > > >       https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
> > >
> > > What exactly depends on this patchset?
> > >
> > > > ---
> > > >  drivers/gpu/drm/msm/msm_drv.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > > > index ed2a61c66ac9..65119fb3dfa2 100644
> > > > --- a/drivers/gpu/drm/msm/msm_drv.c
> > > > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > > > @@ -54,7 +54,7 @@ static bool modeset = true;
> > > >  MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
> > > >  module_param(modeset, bool, 0600);
> > > >
> > > > -static bool separate_gpu_kms;
> > > > +static bool separate_gpu_kms = true;
> > > >  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
> > > >  module_param(separate_gpu_kms, bool, 0400);
> > >
> > > The patch LGTM, but I'd prefer to get confirmation from Rob.
> >
> > I prefer to be a bit more paranoid.. perhaps switch this to a tri-state:
> >
> >  -1: separate drm devices if there is more than one dpu or gpu,
> >      otherwise, single combined drm device [default]
> >   0: single drm device (matching up pairs of dpu and gpu if needed)
> >   1: separate drm devices
> >
> > This way we aren't changing (or breaking) things for existing users.
>
> I'd rather break things and hear about them being broken.

You are assuming you'd hear about the non-obvious breakages
immediately..  I don't think that is a good assumption.

To be clear, I'll NAK any change to the default for "normal" hw
configurations.  If you want to change the modparam to tri-state so
that "weird" hw configurations get split devices, I guess I'd be ok
with that.  At least it limits the potential fallout.

BR,
-R

> >
> > BR,
> > -R
> >
> > > BTW: have you tested it with X11? Are you still getting accelerated GPU?
> > >
> > > --
> > > With best wishes
> > > Dmitry
>
> --
> With best wishes
> Dmitry

Re: [PATCH] drm/msm: enable separate_gpu_kms by default

[Dmitry Baryshkov]

On Tue, Mar 03, 2026 at 03:38:35PM -0800, Rob Clark wrote:
> On Tue, Mar 3, 2026 at 2:32 PM Dmitry Baryshkov
> <dmitry.baryshkov@oss.qualcomm.com> wrote:
> >
> > On Tue, Mar 03, 2026 at 10:35:46AM -0800, Rob Clark wrote:
> > > On Sun, Feb 22, 2026 at 12:32 PM Dmitry Baryshkov
> > > <dmitry.baryshkov@oss.qualcomm.com> wrote:
> > > >
> > > > On Mon, Feb 23, 2026 at 12:40:10AM +0530, Mahadevan P wrote:
> > > > > On targets with multiple display subsystems, such as SA8775P, the GPU
> > > > > binds to the first display subsystem that probes. This implicit binding
> > > > > prevents subsequent display subsystems from probing successfully,
> > > > > breaking multi-display support.
> > > > >
> > > > > Enable separate_gpu_kms by default to decouple GPU and display subsystem
> > > > > probing. This allows each display subsystem to initialize independently,
> > > > > ensuring that all display subsystems are probed.
> > > > >
> > > > > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> > > > > ---
> > > > > Depends on:
> > > > >       https://lore.kernel.org/lkml/20260124-adreno-module-table-v1-1-9c2dbb2638b4@oss.qualcomm.com/
> > > > >       https://lore.kernel.org/all/20260217071420.2240380-1-mkuntuma@qti.qualcomm.com/
> > > >
> > > > What exactly depends on this patchset?
> > > >
> > > > > ---
> > > > >  drivers/gpu/drm/msm/msm_drv.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> > > > > index ed2a61c66ac9..65119fb3dfa2 100644
> > > > > --- a/drivers/gpu/drm/msm/msm_drv.c
> > > > > +++ b/drivers/gpu/drm/msm/msm_drv.c
> > > > > @@ -54,7 +54,7 @@ static bool modeset = true;
> > > > >  MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
> > > > >  module_param(modeset, bool, 0600);
> > > > >
> > > > > -static bool separate_gpu_kms;
> > > > > +static bool separate_gpu_kms = true;
> > > > >  MODULE_PARM_DESC(separate_gpu_drm, "Use separate DRM device for the GPU (0=single DRM device for both GPU and display (default), 1=two DRM devices)");
> > > > >  module_param(separate_gpu_kms, bool, 0400);
> > > >
> > > > The patch LGTM, but I'd prefer to get confirmation from Rob.
> > >
> > > I prefer to be a bit more paranoid.. perhaps switch this to a tri-state:
> > >
> > >  -1: separate drm devices if there is more than one dpu or gpu,
> > >      otherwise, single combined drm device [default]
> > >   0: single drm device (matching up pairs of dpu and gpu if needed)
> > >   1: separate drm devices
> > >
> > > This way we aren't changing (or breaking) things for existing users.
> >
> > I'd rather break things and hear about them being broken.
> 
> You are assuming you'd hear about the non-obvious breakages
> immediately..  I don't think that is a good assumption.
> 
> To be clear, I'll NAK any change to the default for "normal" hw
> configurations.  If you want to change the modparam to tri-state so
> that "weird" hw configurations get split devices, I guess I'd be ok
> with that.  At least it limits the potential fallout.

Ack :-)

> 
> BR,
> -R
> 
> > >
> > > BR,
> > > -R
> > >
> > > > BTW: have you tested it with X11? Are you still getting accelerated GPU?
> > > >
> > > > --
> > > > With best wishes
> > > > Dmitry
> >
> > --
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry