Re: [PATCH] nouveau: Load firmware for BSP/VP engines on NV84-NV96, NVA0

[Maarten Lankhorst <maarten.lankhorst@canonical.com>]

Hey,

Op 04-06-13 20:38, Ilia Mirkin schreef:
> On Mon, Jun 3, 2013 at 5:02 AM, Ilia Mirkin <imirkin@alum.mit.edu> wrote:
>> These chipsets include the VP2 engine which is composed of a bitstream
>> processor (BSP) that decodes H.264 and a video processor (VP) which can
>> do iDCT/mo-comp/etc for MPEG1/2, H.264, and VC-1. Both of these are
>> driven by separate xtensa chips embedded in the hardware. This patch
>> provides the mechanism to load the kernel for the xtensa chips and
>> provide the necessary interactions to do the rest of the work.
>>
>> Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
>> ---
>>
>> This patch applies on top of nouveau/master (16a41bcc8).
>>
>> This seems to work for me. There was one boot where my userspace
>> component didn't work right, but it could just as well be a bug
>> there. Subsequent attempts seem to work fine. Note that I'm not
>> particularly familiar with any of this stuff, so if something looks
>> odd, I probably didn't know any better. I did try to faithfully
>> reproduce whatever the blob did. A few questions/thoughts:
>>
>> 1. There's a LOT of similarity between BSP and VP setup/etc. Is it
>>    worth it to create a core/xtensa.c or some such, similar to
>>    falcon.c? Since it's only in two places, not that much code, and
>>    there _are_ differences, I decided to keep them separate.
>>
>> 2. Firmware naming. Maarten suggested to use the falcon naming style,
>>    which is nv$chipset_fuc$offset. However here, all the chips share
>>    the same firmware. Also the offset would be 103 vs 00f, and is a
>>    little arbitrary. (And fuc doesn't apply here... xt? xtensa?) I've
>>    left it the way I had it: nv84_bsp and nv84_vp.
>>
>> 3. Firmware load time. I chose to load the fw into memory in the ctor,
>>    and then copy it in in init, due to some potentially bogus
>>    suspend/resume concerns. Also e.g. mplayer likes to create/destroy
>>    decoders at startup a few times. The downside is that ~200KB of
>>    memory is gone. Let me know if I should change it to do the
>>    request_firmware in init.
>>
>> There's obviously a userspace piece to this, which I'm still working
>> on. But right now I have it working within certain parameters
>> (e.g. 1280x544 videos), and I'm relatively confident it can be
>> completed without further kernel-side changes.
>>
>> There's also a hypothetical concern of "what if we create an open
>> firmware with a different user API". Ideally there'd be some way to
>> expose what kind of firmware is loaded, but I think that can be left
>> for "later".
> I also happened to notice that NV98, NVA1+ refer to these nv84 engines
> (in drivers/gpu/drm/nouveau/core/engine/device/nv50.c). I assume that
> means I should create a new nv98.c version of BSP/VP that resembles
> the old versions of nv84.c, and point device/nv50.c at those for nv98
> and nva1+?
nv98+ should really have an implementation more like nvc0, and the copy engine
is a good example on what conversion is needed to do it. :-)

If you fix that up, I'll stop being lazy and fix VP4 for nva3/a5/a8 in mesa. ;)

~Maarten