On 15/05/2019 01:06, Rodrigo Vivi wrote:
On Tue, May 14, 2019 at 06:32:01PM +0000, Summers, Stuart wrote:
On Tue, 2019-05-14 at 17:53 +0100, Chris Wilson wrote:
Quoting Stuart Summers (2019-05-14 17:46:52)
To allow easier debug of platforms which do not fully support
power-saving render C-state 6, add back the module parameter
to allow RC6 flows to be disabled. Instead of directly affecting
the RC6 states via a bitmask as done previously, use this module
parameter to clear the has_rc6 field for these platforms.
If you know which platforms don't support rc6, don't enable rc6.
I'd really prefer to have this parameter in place for debug purposes.
It seems more useful to allow quick testing by reloading i915 than by
requiring a rebuild.
Of course, once debug is complete and the platform is known to either
not support the feature or has some cripling bug around this, I agree,
rc6 shouldn't be enabled on that platform and i915 should be updated.
Exactly. We need the flexibility for debug that.
unfortunately using debugfs doesn't look a solution.
One possibility that just came to my mind now is, what if we make
this only for platforms that are still protected by is_alpha_support=1
(soon becoming require_force_probe=1)
But this is just one side of the coin... when product is out there
and we want the user to debug the issue to see if it is a RC6 bug
we have no way to verify that. :/
Please let's add this back one way or another.
To throw a compromise option out there - add the modparam for debug
builds only (CONFIG_DRM_I915_DEBUG)?
Regards,
Tvrtko
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