Hi Danilo, On Tue, 24 Oct 2023 00:57:47 +0200 Danilo Krummrich <dakr@xxxxxxxxxx> wrote: > > > + > > > + /** > > > + * @update_job_credits: Called once the scheduler is considering this > > > + * job for execution. > > > + * > > > + * Drivers may use this to update the job's submission credits, which is > > > + * useful to e.g. deduct the number of native fences which have been > > > + * signaled meanwhile. > > > + * > > > + * The callback must either return the new number of submission credits > > > + * for the given job, or zero if no update is required. > > > > Any reason for having this special zero-means-no-update case? I mean, > > drivers could just return sched_job->submission_credits if nothing > > changed, and that would simplify the semantics IMHO. Another option, if > > I think I just did this because I thought it's a clever way to get rid of the > need to deal with zero-sized jobs, which do not make much sense. In > drm_sched_job_init() passing a zero job size defaults to one, which I think is > reasonable. Doing the same thing here is more likely to hide a bug. However, the > same is probably true for 'zero means no update' though. Maybe we should just > WARN() in such a case. > > > we want to avoid the sched_job->submission_credits assignment when > > nothing changes would be to make it a void function and let it update > > the sched_job->submission_credits directly. > > Sure, that's an option as well. However, I'd probably prefer the new job size to > be the return value. Having to sanity check job->submission_credits afterwards > isn't that nice either. Uh, sorry for the late reply, I see you've sent a v3 already :-/. I keep thinking it'd be simpler to make this a void function that updates s_job->submission_credits directly. I also don't see the problem with doing a sanity check on job->submission_credits. I mean, if the driver is doing something silly, you can't do much to prevent it anyway, except warn the user that something wrong has happened. If you want to WARN_ON(job->submission_credits == 0 || job->submission_credits > job_old_submission_credits); that's fine. But none of this sanity checking has to do with the function prototype/semantics, and I'm still not comfortable with this 0 => no-change. If there's no change, we should just leave job->submission_credits unchanged (or return job->submission_credits) instead of inventing a new special case. Regards, Boris
