Re: Lay common foundation to make PVR/SGX work without hacks on OMAP34xx, OMAP36xx, AM335x and potentially OMAP4, OMAP5

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Hi,

* Philipp Rossak <embed3d@xxxxxxxxx> [190212 22:25]:
> I'm looking now into that PVR SGX driver since a while. I already reworked
> that old "opensource" driver to work with a quite new kernel (4.16 or 4.17)
> [But that code got lost].
> For the sunxi devices this was only a short coding session to get that
> running. For OMAP this might be easier/faster since the general linux
> situation is better.

So a git repo that works for omaps and sunxi would be a good
start then :)

> I'm not sure if we are able to provide a generic driver since there are
> different userspace versions that are only compatible with their own kernel
> driver. Not all compile flags for the kernel driver work with all userspace
> lib versions, at least on sunxi. Be aware that there are also different
> versions of those GPU ip cores and all have different features and bug
> fixes.

No doubt it's a mess.. I'm only suggesting a generic driver that
manages standard Linux resources like regulators, clocks and
interrupts and provides 2d acceleration for sgx540 based on what
we already have at drivers/gpu/drm/gma500/accel_2d.c. The idea
being that it might then also make dealing with the rest of the
sgx blobs a bit easier hopefully.

> If you reach a good state with that driver, I can try to port that to sunxi.
> Is there any good/cheap OMAP4/5 Devboard you can recommend?

Hmm so the n900 folks have the sgx blobs working with recent
mainline kernels for sgx530 I believe, and Nikolaus is close to
having the sgx blobs working for sgx540. I may not be aware of
the current status though.

For a devboard with sgx540, you should be able to find one for
few tens of units for a used pandaboard-es for example or
somebody here might even have an old one to donate. If you feel
like playing with a phone, droid 4 xt894 is somewhat usable
with mainline kernels with pending patches for LCD and modem,
no idea what the sgx540 status on it might be. Pyra handheld
is not yet available except for prototypes. And then on
beagleboard-x15 there's sgx544, and beaglebone has sgx530
FYI so that might not help if you need sgx540.

> Don't expect any support from TI or IMG. TI can't support a project like
> this, since they don't own the code and IMG is not willing to support.

Yeah that we've seen already over past 10 or so years :)

> An other big issue is the leaked SGX source code [1]. So I think it would be
> better to start a clean room reverse engineering project. I'm already
> working on that.

OK so we're discussing at least three projects then:

1. A git repo that allows sgx blobs to work for various
   SoCs with current mainline kernels

2. A generic 2d sgx540 driver based on existing mainline
   kernel drivers/gpu/drm/gma500/accel_2d.c

3. Your reverse engineering project that might help
   with figuring out how things are supposed to work

Regards,

Tony


> [1]: https://libv.livejournal.com/26972.html



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