Re: [PATCH v4 9/9] drm/vkms: convert to use faux_device

[Thomas Zimmermann]

Hi

Am 13.03.25 um 18:20 schrieb José Expósito:
> On Thu, Mar 13, 2025 at 03:22:21PM +0100, Simona Vetter wrote:
> > On Wed, Mar 12, 2025 at 07:22:07AM +0100, Greg KH wrote:
> > > On Tue, Mar 11, 2025 at 06:20:53PM +0100, José Expósito wrote:
> > > > Hi everyone,
> > > >
> > > > > On Tue, Feb 25, 2025 at 02:51:40PM +0100, Louis Chauvet wrote:
> > > > > > Le 25/02/2025 à 12:41, Thomas Zimmermann a écrit :
> > > > > > > Hi
> > > > > > >
> > > > > > > Am 10.02.25 um 15:37 schrieb Louis Chauvet:
> > > > > > > > On 10/02/25 - 13:30, Greg Kroah-Hartman wrote:
> > > > > > > > > The vkms driver does not need to create a platform device, as there is
> > > > > > > > > no real platform resources associated it,  it only did so because it was
> > > > > > > > > simple to do that in order to get a device to use for resource
> > > > > > > > > management of drm resources.  Change the driver to use the faux device
> > > > > > > > > instead as this is NOT a real platform device.
> > > > > > > > >
> > > > > > > > > Cc: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> > > > > > > > > Cc: Haneen Mohammed <hamohammed.sa@xxxxxxxxx>
> > > > > > > > > Cc: Simona Vetter <simona@xxxxxxxx>
> > > > > > > > > Cc: Melissa Wen <melissa.srw@xxxxxxxxx>
> > > > > > > > > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > > > > > > > > Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> > > > > > > > > Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > > > > > > > Cc: David Airlie <airlied@xxxxxxxxx>
> > > > > > > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > > > > > > Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
> > > > > > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > > > > > Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> > > > > > >
> > > > > > > > Tested-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> > > > > > > > Reviewed-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
> > > > > > > >
> > > > > > > > Thanks for the modification, it seems to work.
> > > > > > > Should this patch be merged through DRM trees? drm-misc-next is at
> > > > > > > v6.14-rc4 and has struct faux_device.
> > > > > > Hi,
> > > > > >
> > > > > > I was not aware the faux-device was merged, as it is a new feature, I
> > > > > > expected it to reach drm-misc-next on 6.15-rc1.
> > > > > I added it to Linus's tree just so that DRM could get these changes into
> > > > > their tree now :)
> > > > >
> > > > > > I plan to merge [1] today/tomorrow (well tested with platform_device), and
> > > > > > then I will submit an updated version of this patch (only trivial conflicts,
> > > > > > but never tested with multiple VKMS devices).
> > > > > >
> > > > > > [1]:https://lore.kernel.org/all/20250218101214.5790-1-jose.exposito89@xxxxxxxxx/
> > > > > Great, thanks!
> > > > >
> > > > > greg k-h
> > > > Testing this patch again as part of some IGT tests I'm working on,
> > > > I noticed that, applying this patch on top of the latest drm-misc-next
> > > > triggers a warning at drivers/gpu/drm/drm_gem.c:571, in
> > > > drm_gem_get_pages():
> > > >
> > > >      if (WARN_ON(!obj->filp))
> > > >              return ERR_PTR(-EINVAL);
> > > I don't see how the faux bus change would have anything to do with a
> > > filp as that's not related as far as I can tell.  But I don't know the
> > > drm layer at all, where does that filp come from?
> > Yeah that filp is the shmem file that backs gem bo. That's very far away
> > from anything device/driver related datastrctures. If this is a new
> > failure due to the aux bux conversion then it would be really surprising.
> Agreed, I find it surprising, but reverting the patch removes the warning.
>
> It's most likely an issue on my side, but I decided to double check just
> in case someone else is also seeing this warning.

Any news on this issue?

Best regards
Thomas

> Jose
>
> > -Sima
> >
> > --
> > Simona Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
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