[Mesa-dev] [PATCH v2] loader: Add support for platform and host1x busses

[Thierry Reding]

On Fri, Mar 02, 2018 at 01:31:22PM +0000, Emil Velikov wrote:
> On 2 March 2018 at 11:29, Thierry Reding <thierry.reding at gmail.com> wrote:
> > From: Thierry Reding <treding at nvidia.com>
> >
> > ARM SoCs usually have their DRM/KMS devices on the platform bus, so add
> > support for this bus in order to allow use of the DRI_PRIME environment
> > variable with those devices.
> >
> > While at it, also support the host1x bus, which is effectively the same
> > but uses an additional layer in the bus hierarchy.
> >
> > Note that it isn't enough to support the bus that has the rendering GPU
> > because the loader code will also try to construct an ID path tag for a
> > scanout-only device if it is the default that is being opened.
> >
> > The ID path tag for a device can be obtained by running udevadm info on
> > the device node, as shown in this example on NVIDIA Tegra:
> >
> >         $ udevadm info /dev/dri/card0 | grep ID_PATH_TAG
> >         E: ID_PATH_TAG=platform-50000000_host1x
> >
> > The corresponding OF_FULLNAME property, from which the ID_PATH_TAG is
> > constructed, can be found in the sysfs "uevent" attribute for the card0
> > device's parent:
> >
> >         $ grep OF_FULLNAME /sys/devices/platform/50000000.host1x/drm/uevent
> >         OF_FULLNAME=/host1x at 50000000
> >
> > Similarily, /dev/dri/card1 corresponds to the GPU:
> >
> >         $ udevadm info /dev/dri/card1 | grep ID_PATH_TAG
> >         E: ID_PATH_TAG=platform-57000000_gpu
> >
> > and:
> >
> >         $ grep OF_FULLNAME /sys/devices/platform/57000000.gpu/uevent
> >         OF_FULLNAME=/gpu at 57000000
> >
> > Changes in v2:
> > - avoid confusing pre-increment in strdup()
> > - add examples of tags to commit log
> >
> > Reviewed-by: Eric Engestrom <eric at engestrom.ch>
> > Signed-off-by: Thierry Reding <treding at nvidia.com>
> Smashing, thanks for the examples Thierry.
> 
> Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

Thanks! Pushed to master.

Thierry
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