Nico Huber (nico.h@gmx.de) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/18250
-gerrit
commit 96e2f885c196913cd1aebe43f6fc9c0f0b31df78 Author: Nico Huber nico.h@gmx.de Date: Fri Jan 27 15:55:28 2017 +0100
WIP Documentation/backlight-pwm: Gather backlight PWM infos
Change-Id: I3a3456cee8ed053db13b4b9d2d3f5a8fc04bb7ff Signed-off-by: Nico Huber nico.h@gmx.de --- Documentation/backlight-pwm.md | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+)
diff --git a/Documentation/backlight-pwm.md b/Documentation/backlight-pwm.md new file mode 100644 index 0000000..970646f --- /dev/null +++ b/Documentation/backlight-pwm.md @@ -0,0 +1,25 @@ +# PWM frequencies for display backlights + +## Values found in use by vendors + +* `Lenovo ThinkPad X60`: 0x879e/180Hz (@200MHz CDClk) + +* `Lenovo ThinkPad X200s`: 0x0cf8/753Hz (@320MHz CDClk) + LED backlight, panel: + Manufacturer: LEN Model 4014 Serial Number 0 + ASCII string: LTD121EQ3B + +* `Lenovo ThinkPad X301`: 0x24fc/264Hz (@320MHz CDClk) + LED backlight, panel: + Manufacturer: LEN Model 4074 Serial Number 0 + ASCII string: LTD133EQ1B + +## Often copy-pasted constants + +* `0x0610 for gm45`: First seen in commit 6481e10 + "gma45: Ensure that brightness register in gma contains a sane vaule" + Depending on the CDClk frequency (222MHz .. 333MHz) 1.12kHz .. 1.61kHz + +* `0x0128 for i945`: First seen for lenovo/x60 in commit 26ca08c + "i945: Replace video gfx init." + With a CDClk of 200MHz it gives a 21.1kHz PWM.