On Wed, Mar 26, 2014 at 1:27 PM, Ben Skeggs <skeggsb@xxxxxxxxx> wrote:
> On Tue, Mar 25, 2014 at 9:10 AM, Thierry Reding
> <thierry.reding@xxxxxxxxx> wrote:
>> On Mon, Mar 24, 2014 at 05:42:33PM +0900, Alexandre Courbot wrote:
>>> GK20A does not embed a dedicated COPY engine and thus cannot allocate
>>> the copy channel that nouveau_accel_init() attempts to create. It also
>>> lacks any display hardware, so the creation of a software channel does
>>> not apply neither.
>>
>> Perhaps this should be two separate patches?
>>
>>> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
>> [...]
>>> + if (device->chipset == 0xea) {
>>> + /* gk20a does not have CE0/CE1 */
>>
>> This would be another good candidate for a feature flag.
> There are ways to query this in a chipset-independent way. However,
> despite reporting it as an error if no copy engines are available, the
> code should continue on without the channel happily. Perhaps we can
> just punt the relevent error messages to a debug loglevel for now?
Sure, that would be more future-proof as well.
>
>>
>>> + arg0 = NVE0_CHANNEL_IND_ENGINE_GR;
>>> + arg1 = 1;
>>> + } else
>>> if (device->card_type >= NV_E0) {
>>
>> The formatting here is somewhat weird. From a brief look I couldn't find
>> any indication that nouveau deviates from the standard coding style, so
>> this should be:
>>
>> } else if (...) {
> I use the former in a few places, despite it not entirely being
> "correct".. It looks nicer though :) I don't mind either way though.
Yeah, I just followed the style of the file here. Whether it needs to
change or not is not my call. :P
>>> + /* Need to figure out how to handle sw for gk20a */
>>> + if (device->chipset == 0xea)
>>> + goto skip_sw_init;
>>
>> The commit message makes it sound like SW isn't needed since gk20a
>> "lacks any display hardware". In that case the comment here doesn't make
>> much sense.
Correct. As far as I have looked (that is, not very far), SW methods
are used for display-related functions, but there might be other
use-cases too. Maybe someone who knows better can confirm?
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