From: Daniel Vetter <daniel@ffwll.ch>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: airlied@linux.ie, hdegoede@redhat.com,
dri-devel@lists.freedesktop.org, sean@poorly.run
Subject: Re: [PATCH 0/3] drm: Store USB device in struct drm_device
Date: Wed, 21 Oct 2020 22:01:29 +0200 [thread overview]
Message-ID: <20201021200129.GQ401619@phenom.ffwll.local> (raw)
In-Reply-To: <20201021130732.4048-1-tzimmermann@suse.de>
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
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next prev parent reply other threads:[~2020-10-21 20:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 13:07 [PATCH 0/3] drm: Store USB device in struct drm_device Thomas Zimmermann
2020-10-21 13:07 ` [PATCH 1/3] drm: Add reference to USB device to " Thomas Zimmermann
2020-10-21 13:07 ` [PATCH 2/3] drm/tiny/gm12u320: Store USB device in struct drm_device.udev Thomas Zimmermann
2020-10-21 13:07 ` [PATCH 3/3] drm/udl: " Thomas Zimmermann
2020-10-21 20:01 ` Daniel Vetter [this message]
2020-10-21 20:05 ` [PATCH 0/3] drm: Store USB device in struct drm_device Daniel Vetter
2020-10-22 9:20 ` Hans de Goede
2020-10-22 9:30 ` Thomas Zimmermann
2020-10-22 10:17 ` Hans de Goede
2020-10-22 10:57 ` Thomas Zimmermann
2020-10-22 11:32 ` Hans de Goede
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