[RFC PATCH v2 17/17] WIP: drm/tegra: Implement new UAPI

[Mikko Perttunen]

On 9/11/20 12:57 AM, Dmitry Osipenko wrote:
> 09.09.2020 11:36, Mikko Perttunen пишет:
> ...
>>>
>>> Does it make sense to have timeout in microseconds?
>>>
>>
>> Not sure, but better have it a bit more fine-grained rather than
>> coarse-grained. This still gives a maximum timeout of 71 minutes so I
>> don't think it has any negatives compared to milliseconds.
> 
> If there is no good reason to use microseconds right now, then should be
> better to default to milliseconds, IMO. It shouldn't be a problem to
> extend the IOCLT with a microseconds entry, if ever be needed.
> 
> {
> 	__u32 timeout_ms;
> ...
> 	__u32 timeout_us;
> }
> 
> timeout = timeout_ms + 1000 * timeout_us;
> 
> There shouldn't be a need for a long timeouts, since a job that takes
> over 100ms is probably too unpractical. It also should be possible to
> detect a progressing job and then defer timeout in the driver. At least
> this is what other drivers do, like etnaviv driver for example:
> 
> https://elixir.bootlin.com/linux/v5.9-rc4/source/drivers/gpu/drm/etnaviv/etnaviv_sched.c#L107
> 

I still don't quite understand why it's better to default to 
milliseconds? As you say, there is no need to have a long timeout, and 
if we go microseconds now, then there wouldn't be a need to extend in 
the future.

Mikko