[coreboot-gerrit] Patch set updated for coreboot: WIP Documentation/backlight-pwm: Gather backlight PWM infos
Arthur Heymans (arthur@aheymans.xyz)
gerrit at coreboot.org
Wed Feb 1 22:07:34 CET 2017
Arthur Heymans (arthur at aheymans.xyz) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/18250
-gerrit
commit f49809fb14b197e57eafcf0d2a2b7d28213bc384
Author: Nico Huber <nico.h at 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 at gmx.de>
Signed-off-by: Arthur Heymans <arthur at aheymans.xyz>
---
Documentation/backlight-pwm.md | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/Documentation/backlight-pwm.md b/Documentation/backlight-pwm.md
new file mode 100644
index 0000000..fbb1b2a
--- /dev/null
+++ b/Documentation/backlight-pwm.md
@@ -0,0 +1,27 @@
+# PWM frequencies for display backlights
+
+## Values found in use by vendors
+
+* `Lenovo Thinkpad T60`: 0x58be/275Hz (@200MHz CDClk)
+
+* `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.
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