Coverity: nvkm_dp_train(): Integer handling issues

Hello!

This is an experimental semi-automated report about issues detected by Coverity from a scan of next-20221110 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified lines of code (noted below) that were touched by commits:

Wed Nov 9 10:43:10 2022 +1000
8bb30c882334 ("drm/nouveau/disp: add method to trigger DP link retrain")

Coverity reported the following:

*** CID 1527267: Integer handling issues (NEGATIVE_RETURNS) drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c:458 in nvkm_dp_train()
452 u8 pwr;
453

454     	/* Retraining link?  Skip source configuration, it can mess up the active modeset. */
455     	if (atomic_read(&outp->dp.lt.done)) {
456     		for (rate = 0; rate < outp->dp.rates; rate++) {
457     			if (outp->dp.rate[rate].rate == ior->dp.bw * 27000)
vvv     CID 1527267:  Integer handling issues  (NEGATIVE_RETURNS)
vvv     "ret" is passed to a parameter that cannot be negative.
458     				return nvkm_dp_train_link(outp, ret);
459     		}
460     		WARN_ON(1);
461     		return -EINVAL;
462     	}

463

If this is a false positive, please let us know so we can mark it as such, or teach the Coverity rules to be smarter. If not, please make sure fixes get into linux-next. :) For patches fixing this, please include these lines (but double-check the "Fixes" first):

Addresses-Coverity-ID: 1527267 ("Integer handling issues")

Thanks for your attention!

Coverity-bot