Re: [Intel-gfx] [PATCH 3/5] drm/amdgpu: Paper over the drm_driver mangling for virt

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Nov 03, 2020 at 11:49:40AM -0500, Alex Deucher wrote:
> On Sun, Nov 1, 2020 at 5:01 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> >
> > On Sat, Oct 31, 2020 at 2:57 PM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > >
> > > On Fri, Oct 30, 2020 at 7:47 PM Alex Deucher <alexdeucher@gmail.com> wrote:
> > > >
> > > > On Fri, Oct 30, 2020 at 6:11 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> > > > >
> > > > > Prep work to make drm_device->driver const.
> > > > >
> > > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > > > > Cc: Alex Deucher <alexander.deucher@amd.com>
> > > > > Cc: "Christian König" <christian.koenig@amd.com>
> > > > > Cc: Evan Quan <evan.quan@amd.com>
> > > > > Cc: Felix Kuehling <Felix.Kuehling@amd.com>
> > > > > Cc: Hawking Zhang <Hawking.Zhang@amd.com>
> > > > > Cc: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
> > > > > Cc: Luben Tuikov <luben.tuikov@amd.com>
> > > > > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > > > > Cc: Monk Liu <Monk.Liu@amd.com>
> > > > > Cc: Yintian Tao <yttao@amd.com>
> > > > > Cc: Dennis Li <Dennis.Li@amd.com>
> > > > > Cc: shaoyunl <shaoyun.liu@amd.com>
> > > > > Cc: Bokun Zhang <Bokun.Zhang@amd.com>
> > > > > Cc: "Stanley.Yang" <Stanley.Yang@amd.com>
> > > > > Cc: Wenhui Sheng <Wenhui.Sheng@amd.com>
> > > > > Cc: chen gong <curry.gong@amd.com>
> > > > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > > > > ---
> > > > >  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c  |  8 ++++----
> > > > >  drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 12 +++++++++++-
> > > > >  2 files changed, 15 insertions(+), 5 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > > > index 024c3b70b1aa..3d337f13ae4e 100644
> > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> > > > > @@ -1093,7 +1093,7 @@ static const struct pci_device_id pciidlist[] = {
> > > > >
> > > > >  MODULE_DEVICE_TABLE(pci, pciidlist);
> > > > >
> > > > > -static struct drm_driver kms_driver;
> > > > > +struct drm_driver amdgpu_kms_driver;
> > > > >
> > > > >  static int amdgpu_pci_probe(struct pci_dev *pdev,
> > > > >                             const struct pci_device_id *ent)
> > > > > @@ -1164,7 +1164,7 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
> > > > >         if (ret)
> > > > >                 return ret;
> > > > >
> > > > > -       adev = devm_drm_dev_alloc(&pdev->dev, &kms_driver, typeof(*adev), ddev);
> > > > > +       adev = devm_drm_dev_alloc(&pdev->dev, &amdgpu_kms_driver, typeof(*adev), ddev);
> > > > >         if (IS_ERR(adev))
> > > > >                 return PTR_ERR(adev);
> > > > >
> > > > > @@ -1508,7 +1508,7 @@ int amdgpu_file_to_fpriv(struct file *filp, struct amdgpu_fpriv **fpriv)
> > > > >         return 0;
> > > > >  }
> > > > >
> > > > > -static struct drm_driver kms_driver = {
> > > > > +struct drm_driver amdgpu_kms_driver = {
> > > > >         .driver_features =
> > > > >             DRIVER_ATOMIC |
> > > > >             DRIVER_GEM |
> > > > > @@ -1571,7 +1571,7 @@ static int __init amdgpu_init(void)
> > > > >                 goto error_fence;
> > > > >
> > > > >         DRM_INFO("amdgpu kernel modesetting enabled.\n");
> > > > > -       kms_driver.num_ioctls = amdgpu_max_kms_ioctl;
> > > > > +       amdgpu_kms_driver.num_ioctls = amdgpu_max_kms_ioctl;
> > > > >         amdgpu_register_atpx_handler();
> > > > >
> > > > >         /* Ignore KFD init failures. Normal when CONFIG_HSA_AMD is not set. */
> > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> > > > > index d0aea5e39531..dde4c449c284 100644
> > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> > > > > @@ -45,13 +45,23 @@ bool amdgpu_virt_mmio_blocked(struct amdgpu_device *adev)
> > > > >         return RREG32_NO_KIQ(0xc040) == 0xffffffff;
> > > > >  }
> > > > >
> > > > > +extern struct drm_driver amdgpu_kms_driver;
> > > > > +
> > > > >  void amdgpu_virt_init_setting(struct amdgpu_device *adev)
> > > > >  {
> > > > >         /* enable virtual display */
> > > > >         if (adev->mode_info.num_crtc == 0)
> > > > >                 adev->mode_info.num_crtc = 1;
> > > > >         adev->enable_virtual_display = true;
> > > > > -       adev_to_drm(adev)->driver->driver_features &= ~DRIVER_ATOMIC;
> > > > > +
> > > > > +       /*
> > > > > +        * FIXME: Either make virt support atomic or make sure you have two
> > > > > +        * drm_driver structs, these kind of tricks are only ok when there's
> > > > > +        * guaranteed only a single device per system. This should also be done
> > > > > +        * before struct drm_device is initialized.
> > > > > +        */
> > > > > +       amdgpu_kms_driver.driver_features &= ~DRIVER_ATOMIC;
> > > >
> > > > There is additional DRIVER_ATOMIC in amdgpu_pci_probe() for older
> > > > chips without atomic support.
> > >
> > > That would need to be fixed for making the amdgpu drm_driver
> > > structures constant, but that's not what I'm doing here. I'm only
> > > removing the usage of the drm_device->driver pointer, to allow that to
> > > become constant. Untangling the flow to make the amdgpu_kms_driver
> > > const looked a bit more involved than just a  simple patch.
> >
> > On second look, this changes the drm_device->driver_features flag,
> > which was added to avoid having to change the drm_driver one. So
> > that's actually all ok (and just the virt code here is broken). But
> > amdgpu also updates num_ioctl and other stuff, and that's a fairly
> > invasive patch.
> 
> We don't change the number of ioctls:
> const int amdgpu_max_kms_ioctl = ARRAY_SIZE(amdgpu_ioctls_kms);
> So I think the only thing here is the driver features flag for the
> virt display code, or am I missing something?

You set the num_ioctl at runtime, not compile time. That's enough to
prevent constification. Moving that around to make it compile time means a
_lot_ of code shuffling, much more than I felt was a good idea for me to
do :-)

And for the virt case you could use drm_device->driver_flags instead to
avoid this.

Note I don't really care for this series whether you're changing your
drm_driver at runtime or not, I just want to make it possible for drivers
to make it const, which means drm_device->driver must be a const pointer.
Whether you want to make the amdgpu drm_driver const or not is up to you.
-Daniel

> 
> Alex
> 
> 
> >
> > I'm also not sure whether this code here can just be switched over
> > from drm_driver->driver_features to drm_device->driver_features. So
> > given all this, ok as-is and you guys figure out how to patch this
> > properly, or want me to change something in this patch?
> >
> > Cheers, Daniel
> >
> > >
> > > > Alex
> > > >
> > > > > +
> > > > >         adev->cg_flags = 0;
> > > > >         adev->pg_flags = 0;
> > > > >  }
> > > > > --
> > > > > 2.28.0
> > > > >
> > > > > _______________________________________________
> > > > > dri-devel mailing list
> > > > > dri-devel@lists.freedesktop.org
> > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > >
> > >
> > >
> > > --
> > > Daniel Vetter
> > > Software Engineer, Intel Corporation
> > > http://blog.ffwll.ch
> >
> >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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