Indeed as mentioned before it is defined to: register "gpu_backlight" = "0x879F879E"
Question is, what should it become to avoid the whining? 0x79417940 as in the comments? 0x6100610 as in the patch on http://review.coreboot.org/#/c/6731/7/src/northbridge/intel/i945/gma.c that hardcoded the value and removed gpu_backlight? (if anyone else uses a 1400x1050 screen I'd be interested to know if it's the case with "native" screens too) Also, is anyone else experiencing the suspend2ram issues? The kernel is booted with i915.fastboot=1 but I don't think it happened before. (I can try with an older kernel) Thanks Charles On Mon, Apr 6, 2015 at 1:50 AM, The Gluglug <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > BLC_PWM_CTL is in src/mainboard/lenovo/x60/devicetree.cb, see > gpu_brightness or gpu_backlight or something like that. You can change > the value there. > > On 06/04/15 05:54, Charles Devereaux wrote: > > Hello > > > > On my X60 tablet, after a screen swap for a 1400x1050 screen, I > > started noticing a whine. The noise is proportional to the > > reduction of the backlight and doesn't happen at full brightness. I > > never noticed it before. > > > > It happens regardless of how I change the backlight (fn+home/end, > > xbacklight, custom script reading and writing to > > /sys/class/backlight/intel_backlight/brightness) so I suspect a > > coreboot issue. > > > > I am currently using an old libreboot based on head > > 8ffc085e1affaabbe3dca8ac6a89346b71dfc02e with #5345, #7050, #7051, > > but not #6731 and #7049 (since they were dropped and I do not need > > acpi backlight) that works just fine, so I am a bit reluctant to > > change it. > > > > Apparently #6731 and #7049 had the same problem: "some lower > > brightness levels make the high-pitched noise", which was fixed cf > > http://review.coreboot.org/#/c/6731/ > > > > After looking at the code, I see a note explaining how: "Francis > > tested that like my noise issue it doesn't occur with a lower PWM > > frequency. > > > > If we compute the frequency as (0x61 << 8) + (0x61 << 6) + 1 (the 1 > > is to allow legacy backlight brightness which the VGA ROM allows > > and I don't know if it should be enabled) and duty cycle as (x << > > 8) + (x << 6) for x in 0xf, ..., 0x61, then both our issues are > > solved. > > > > I don't know if the resulting value (0x79417940) gives low enough > > frequency to cause flickering for other users: " > > > > I do not fully understand where or how the PWM frequency is set in > > src/northbridge/intel/i945/gma.c. I never see that 0x79417940 > > either. the only thing I see in > > http://review.coreboot.org/#/c/6731/7/src/northbridge/intel/i945/gma.c > > is: > > > > write32(pmmio + BLC_PWM_CTL, 0x6100610); > > > > In the source of my libreboot, it is still: > > > > write32(pmmio + BLC_PWM_CTL, conf->gpu_backlight); > > > > With src/mainboard/lenovo/x60/devicetree.cb setting it with: > > > > register "gpu_backlight" = "0x879F879E" > > > > Should it get changed to: > > > > write32(pmmio + BLC_PWM_CTL, 0x79417940) The other thing I noticed > > were kernel warnings on wakeup from suspend2ram: [54557.710112] > > [drm:intel_pipe_config_compare] *ERROR* mismatch in > > gmch_pfit.pgm_ratios (expected 24183152, found 24117616) > > [54557.710114] ------------[ cut here ]------------ [54557.710121] > > WARNING: CPU: 1 PID: 1432 at > > drivers/gpu/drm/i915/intel_display.c:9541 > > check_crtc_state+0x759/0xe31() [54557.710122] pipe state doesn't > > match! > > > > It may be related. Which coreboot head/patches is libreboot on the > > X60 presently using? > > > > Thanks Charles > > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > > iQEcBAEBAgAGBQJVIh6qAAoJEP9Ft0z50c+UUCEIALbSvFrymaYCKs9d7YTnR5NC > vJkvDNZ5NknB5Q8LjcQuhf9RQ+KMVgxF28sLWL7Bc9ikHgZvH1jH5ykAn7x4rBjO > AUp2l+7NrUnziEllJDQPkfQksy45yMr/c8qZgBm+yeIEPAkM3zRc4k5LNhqmlaPI > AhrUG1sFLt7EAvXqgnlq5jNr/8ogZh9A7Q4I2sWka4UmVj+VhZnG0XNu5a94GqYe > HTyu0OgOYTiPwOQiVyzGPeN+dGYiz86aHyi49uv1nRlaowk8hNXa19prXuf6fVQV > cczdPfs5CMFYBlGKjKz3lq2eg6ARKnuQVCH4wq0HaR0ztbUABwwY3UpWEd3FyJc= > =1AmA > -----END PGP SIGNATURE----- >
