On Tue, 12 Apr 2016, Alexandra Yates <alexandra.yates@xxxxxxxxxxxxxxx> wrote: > Permits the user to identify and toggle values for PSR, FBC, RC6, > DRRS, and IPS under /sys/class/drm/card0/power/. By enabling these > features I'm looking to empower our customers, such as, power team, > chrome OS, and platform integration teams to debug graphics power > management features. Most of these features have module parameters to enable or disable them, with platform specific defaults. We enable and support each feature on each platform where we have confidence it actually works. Conversely, we don't support the features on platforms where we know they don't work, and are therefore disabled by default. To underline this, the module parameters are labeled "unsafe", and setting them taints the kernel. You change the defaults, you're on your own. If you google for the i915 module parameters, you'll find plenty of pages recommending the users to set the various module parameters, typically to gain power savings. It seems to me more often than not people don't understand what they're doing when they enable the features. It's not uncommon to see dmesgs in bug reports with all kinds of module parameters set, regardless of whether they are relevant on the platform in question or not, and it's not uncommon for the module parameters to be the reason for the issue the bug reporter is seeing. With this background, I am feeling rather hesitant about exposing all of these features as an ABI through the sysfs. I fear the end result is going to be PowerTOP recommending users to change the settings, leading to more bug reports. I understand your intention is to help developers, but from the ABI perspective there's really no such thing as "sysfs for developers only". I'd probably feel less uneasy about having these in the debugfs, because that sets the expectations right. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
