Re: Binding together tegradrm & nvhost

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 08/20/2012 07:01 AM, Terje Bergström wrote:
> Hi,
> 
> I've been trying to figure out the best way to bind together tegradrm
> and nvhost. I assume that nvhost and tegradrm will live as separate
> drivers, with tegradrm taking care of display controller, and nvhost
> taking care of host1x and other client devices.
> 
> I've identified a bumps that we need to agree on. I've included here the
> problem and my proposal:
> 
> 1) Device & driver registration
> tegradrm registers as platform_driver, and exports ioctl's. Here we
> already have to agree on which device the platform_driver maps to.
> Currently it maps to host1x, but we'll need to move control of host1x to
> nvhost driver. We'll need to pass drm_platform_init() some
> platform_device - I propose that we create a virtual device for this.

I don't think there's any need for a virtual device. There's one device
in HW, and that can be represented by a single device object within the
kernel. There's nothing then stopping that device exposing multiple
APIs, i.e. providing host1x APIs to clients, and also instantiating the
tegra-drm driver directly on top of the host1x device.