[PATCH 0/3] drm: Store USB device in struct drm_device

[Daniel Vetter]

On Wed, Oct 21, 2020 at 03:07:29PM +0200, Thomas Zimmermann wrote:
> The drivers gm12u320 and udl operate on USB devices. They leave the
> PCI device in struct drm_device empty and store the USB device in their
> own driver structure.
> 
> Fix this special case and save a few bytes by putting the USB device
> into an anonymous union with the PCI data. It's expected that DRM
> core and helpers only touch the PCI-device field for actual PCI devices.

Uh no.

If you're really concerned about the 8 bytes wasted, use drm_device->dev
instead, and upcast it to the usb device. I think some drivers do this
already (at least on the platform side iirc).

But we had this entire drm_bus midlayer stuff already, and it took forever
to sunset it. I don't want to go back, and saving 8 bytes in a giantic
structure isn't worth that risk imo.
-Daniel

> 
> Thomas Zimmermann (3):
>   drm: Add reference to USB device to struct drm_device
>   drm/tiny/gm12u320: Store USB device in struct drm_device.udev
>   drm/udl: Store USB device in struct drm_device.udev
> 
>  drivers/gpu/drm/tiny/gm12u320.c     | 52 +++++++++++++----------------
>  drivers/gpu/drm/udl/udl_connector.c |  8 ++---
>  drivers/gpu/drm/udl/udl_drv.c       |  2 +-
>  drivers/gpu/drm/udl/udl_drv.h       |  1 -
>  drivers/gpu/drm/udl/udl_main.c      | 15 +++++----
>  include/drm/drm_device.h            | 21 ++++++++----
>  6 files changed, 52 insertions(+), 47 deletions(-)
> 
> --
> 2.28.0
> 

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