[Intel-gfx] *cringe* at adding a parameter to workaround issues.

[Marc Herbert]

Hi Jani,

> *cringe* at adding a parameter to workaround issues.

I understand that *each* parameter has the potential to *multiply* the total
number of configurations and that the resulting combinatorial explosion is
absolutely not scalable and sustainable from a validation perspective. No
one should expect to get support here when options like this one are set to
a non-default value.

When something breaks on the other hand, transparent _test_ knobs like this
one have proved invaluable countless times to help troubleshoot and isolate
issues. It's at least 10 times more productive to ask a non-expert in some
opposite timezone "please test again after rebooting with this parameter"
compared to "test again after applying this patch, recompiling, etc." -
assuming the latter has any chance of success at all.  I'm speaking from
actual experience as we are routinely experiencing both type of situations.

I hope the "unsafe" part of "i915_param_named_unsafe" provides a permanent
solution to both problems by making a clear distinction between the only one
single true supported configuration on one hand versus test datapoints
on the other hand.  Same for "tainted", sysfs or else.

Marc