[jwegman]

just updated to #0821 and it has video stuttering issues again. i tried to apply the i915_min_freq fix but it gave me a permission denied error.

text:


Livingroom:~ # echo 756 > /sys/kernel/debug/dri/0/i915_min_freq

-sh: can't create /sys/kernel/debug/dri/0/i915_min_freq: Permission denied

 FYI; I'm also seeing the same thing on my Apollo Lake nuc6 upon upgrading to the latest 9/14/18 build (I'd been running 708b prior, but still had i915_min_freq forced to max...).

What I'm finding, is that when *not* using refresh rate switching, upon keeping an eye on the Current freq, when it drops below 200, I get visual stutter

Code:

# watch cat /sys/kernel/debug/dri/0/i915_frequency_info |grep 'Current freq'
...
Current freq: 267 MHz
Current freq: 283 MHz
Current freq: 233 MHz
Current freq: 250 MHz
Current freq: 250 MHz
Current freq: 250 MHz
Current freq: 217 MHz
Current freq: 233 MHz
Current freq: 217 MHz
Current freq: 217 MHz
Current freq: 217 MHz
Current freq: 217 MHz
Current freq: 167 MHz
Current freq: 217 MHz
Current freq: 217 MHz
Current freq: 150 MHz
Current freq: 250 MHz
...

Here's a debug log http://ix.io/1mLh when refresh rate switching is turned off, however the issue doesn't seem to occur as frequently when debug is turned on, due to what I suspect is the additional frequency boost needed to drive the debug OSD...

When I have refresh rate switching turned on, the current freq rarely exceeds 117 and the video doesn't noticeably stutter (but I rarely have refresh rate switching turned on):

Code:

# watch cat /sys/kernel/debug/dri/0/i915_frequency_info |grep 'Current freq'
...
Current freq: 117 MHz
Current freq: 117 MHz
Current freq: 117 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 100 MHz
Current freq: 117 MHz
Current freq: 100 MHz
Current freq: 117 MHz
Current freq: 100 MHz
Current freq: 117 MHz
Current freq: 117 MHz
Current freq: 117 MHz
Current freq: 100 MHz
Current freq: 100 MHz
...

 

Code:

# cat /sys/kernel/debug/dri/0/i915_frequency_info
Video Turbo Mode: yes
HW control enabled: yes
SW control enabled: no
PM IER=0x00000000 IMR=0xffffffff ISR=0x00000000 IIR=0x00000000, MASK=0x00003ffe
pm_intrmsk_mbz: 0x80000000
GT_PERF_STATUS: 0x00000000
Render p-state ratio: 0
Render p-state VID: 0
Render p-state limit: 0
RPSTAT1: 0x03000000
RPMODECTL: 0x00000d92
RPINCLIMIT: 0x00004740
RPDECLIMIT: 0x00007f80
RPNSWREQ: 100MHz
CAGF: 100MHz
RP CUR UP EI: 174 (145us)
RP CUR UP: 176 (146us)
RP PREV UP: 0 (0us)
Up threshold: 95%
RP CUR DOWN EI: 181 (150us)
RP CUR DOWN: 183 (152us)
RP PREV DOWN: 0 (0us)
Down threshold: 85%
Lowest (RPN) frequency: 100MHz
Nominal (RP1) frequency: 250MHz
Max non-overclocked (RP0) frequency: 750MHz
Max overclocked frequency: 750MHz
Current freq: 100 MHz
Actual freq: 100 MHz
Idle freq: 100 MHz
Min freq: 100 MHz
Boost freq: 750 MHz
Max freq: 750 MHz
efficient (RPe) frequency: 250 MHz
Current CD clock frequency: 288000 kHz
Max CD clock frequency: 624000 kHz
Max pixel clock frequency: 624000 kHz