Re: [PATCH 15/44] drm/udl: Use demv_drm_dev_alloc

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Sun, Apr 5, 2020 at 12:18 PM Noralf Trønnes <noralf@tronnes.org> wrote:
>
>
>
> Den 03.04.2020 15.57, skrev Daniel Vetter:
> > Also init the fbdev emulation before we register the device, that way
> > we can rely on the auto-cleanup and simplify the probe error code even
> > more.
> >
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Dave Airlie <airlied@redhat.com>
> > Cc: Sean Paul <sean@poorly.run>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Emil Velikov <emil.l.velikov@gmail.com>
> > Cc: Sam Ravnborg <sam@ravnborg.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > ---
> >  drivers/gpu/drm/udl/udl_drv.c | 36 +++++++++++------------------------
> >  1 file changed, 11 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
> > index 1ce2d865c36d..4ba5149fdd57 100644
> > --- a/drivers/gpu/drm/udl/udl_drv.c
> > +++ b/drivers/gpu/drm/udl/udl_drv.c
> > @@ -57,27 +57,20 @@ static struct udl_device *udl_driver_create(struct usb_interface *interface)
> >       struct udl_device *udl;
> >       int r;
> >
> > -     udl = kzalloc(sizeof(*udl), GFP_KERNEL);
> > -     if (!udl)
> > -             return ERR_PTR(-ENOMEM);
> > -
> > -     r = drm_dev_init(&udl->drm, &driver, &interface->dev);
> > -     if (r) {
> > -             kfree(udl);
> > -             return ERR_PTR(r);
> > -     }
> > +     udl = devm_drm_dev_alloc(&interface->dev, &driver,
> > +                              struct udl_device, drm);
> > +     if (IS_ERR(udl))
> > +             return udl;
> >
> >       udl->udev = udev;
> >       udl->drm.dev_private = udl;
> > -     drmm_add_final_kfree(&udl->drm, udl);
> >
> >       r = udl_init(udl);
> > -     if (r) {
> > -             drm_dev_put(&udl->drm);
> > +     if (r)
> >               return ERR_PTR(r);
> > -     }
> >
> >       usb_set_intfdata(interface, udl);
> > +
> >       return udl;
> >  }
> >
> > @@ -91,23 +84,17 @@ static int udl_usb_probe(struct usb_interface *interface,
> >       if (IS_ERR(udl))
> >               return PTR_ERR(udl);
> >
> > +     r = drm_fbdev_generic_setup(&udl->drm, 0);
>
> It doesn't feel right to have a client open the device before the DRM
> device itself is registered. I would prefer to keep it where it is but
> ignore any errors. A failing client shouldn't prevent the driver from
> probing. drm_fbdev_generic_setup() do print errors if it fails. So yeah,
> in hindsight I should have made drm_fbdev_generic_setup() return void.

Hm, we have all kinds of usage right now, some check for errors, some
dont, some do this before drm_dev_register, some after. If your
recommendation is to not check for errors then I'm happy to implement
that, but we're a bit inconsistent. Maybe we should do a patch that at
least always returns 0 no matter what, plus document that the return
value  shouldn't be checked?
-Daniel

>
> Noralf.
>
> > +     if (r)
> > +             return r;
> > +
> >       r = drm_dev_register(&udl->drm, 0);
> >       if (r)
> > -             goto err_free;
> > +             return r;
> >
> >       DRM_INFO("Initialized udl on minor %d\n", udl->drm.primary->index);
> >
> > -     r = drm_fbdev_generic_setup(&udl->drm, 0);
> > -     if (r)
> > -             goto err_drm_dev_unregister;
> > -
> >       return 0;
> > -
> > -err_drm_dev_unregister:
> > -     drm_dev_unregister(&udl->drm);
> > -err_free:
> > -     drm_dev_put(&udl->drm);
> > -     return r;
> >  }
> >
> >  static void udl_usb_disconnect(struct usb_interface *interface)
> > @@ -117,7 +104,6 @@ static void udl_usb_disconnect(struct usb_interface *interface)
> >       drm_kms_helper_poll_fini(dev);
> >       udl_drop_usb(dev);
> >       drm_dev_unplug(dev);
> > -     drm_dev_put(dev);
> >  }
> >
> >  /*
> >



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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