<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [NVC1] HDMI audio device only visible after rescan" href="https://bugs.freedesktop.org/show_bug.cgi?id=75985#c51">Comment # 51</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [NVC1] HDMI audio device only visible after rescan" href="https://bugs.freedesktop.org/show_bug.cgi?id=75985">bug 75985</a> from <a class="email" href="mailto:lukas@wunner.de" title="Lukas Wunner <lukas@wunner.de>"> Lukas Wunner</a> <pre>(In reply to Maik Freudenberg from <a href="show_bug.cgi?id=75985#c31">comment #31</a>) > As a sidenote: another user reported 5 Watts additional power draw when > enabling the audio function. Regardless of this being accurate it should be > taken into account to not enable it unconditionally since these are mobile > devices. On my GK107 I do not see any change in power consumption regardless whether bit 25 at config space offset 0x488 is set or cleared, which is somewhat disappointing. I also do not see a change in power consumption between PCI power state D0 and D3hot. So if it's true that enabling the HDA increases power consumption, that would seem to only apply to newer cards. Could somebody verify this: Do you see a consistent drop or increase in power consumption when enabling/disabling the HDA? setpci -s 01:00.0 0x488.l=0x0000000:0x2000000 # disable setpci -s 01:00.0 0x488.l=0x2000000:0x2000000 # enable Try this a couple of times and see if powertop shows a consistent difference in power consumption. (The laptop needs to run on battery for this to work, so disconnect the charger.) If you *do* see a difference, double-check whether runtime suspending the HDA to D3hot (using my above-linked switcheroo_devlink_v2 patch set) also shows a difference. You can force the HDA into D0 or let it autosuspend to D3hot like this: echo on > /sys/bus/pci/devices/0000:01:00.1/power/control # disable echo auto > /sys/bus/pci/devices/0000:01:00.1/power/control # enable If the reduction in power consumption turns out to be the same in D3hot versus disabling via bit 25, there's no point in adding D3cold support to hda_intel.c.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>