On Wed, Oct 21, 2020 at 10:01:29PM +0200, Daniel Vetter wrote: > 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. Typing this I realized that we could even move the pdev pointer to the legacy chunk of drm_device. Instead of checking for drm_device->pdev we could instead check for dev_is_pci(drm_device->dev) in the 1-2 core code places. But it's a pile of churn to roll that out to drivers, and I'm not sure the 8 bytes saved is even close to paying for that huge effort. -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 -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
