Daniel Maslowski has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/33265
Change subject: Documentation: libgfxinit timing parameters ......................................................................
Documentation: libgfxinit timing parameters
Change-Id: If1a393578556d51499c700b68187034830d19215 Signed-off-by: Daniel Maslowski daniel.maslowski@img.ly --- A Documentation/gfx/intel-gma.md M Documentation/gfx/libgfxinit.md M Documentation/index.md 3 files changed, 43 insertions(+), 0 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/65/33265/1
diff --git a/Documentation/gfx/intel-gma.md b/Documentation/gfx/intel-gma.md new file mode 100644 index 0000000..d6a3992 --- /dev/null +++ b/Documentation/gfx/intel-gma.md @@ -0,0 +1,39 @@ +Intel GMA (Graphics Media Accelerator) Specifics +================================================ + +Timing Parameters +----------------- + +From the binary file `edid` in the sys filesystem on Linux, the panel can be +identified. The exact path may differ slightly. Here is an example: + +```sh +$ strings /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/edid +@0 5 +LG Display +LP140WF3-SPD1 +``` + +To figure out the timing parameters, refer to the [Intel Programmer's Reference +Manuals](https://01.org/linuxgraphics/documentation/hardware-specification-prms) +and try to find the datasheet of the panel using the information from `edid`. +In the example above, you would search for `LP140WF3-SPD1`. Find a table listing +the power sequence timing parameters, which are usually named T[N] and also +referenced in Intel's respective registers listing. You need the values for +`PP_ON_DELAYS`, `PP_OFF_DELAYS` and `PP_DIVISOR` for your `devicetree.cb`: + +```eval_rst ++----------------------------+---------------------------------------+--------+ +|Intel docs | devicetree.cb | Haswell| ++----------------------------+---------------------------------------+--------+ +|Power up delay | `gpu_panel_power_up_delay` | T3 | ++----------------------------+---------------------------------------+--------+ +|Power on to backlight on | `gpu_panel_power_backlight_on_delay` | T7 | ++----------------------------+---------------------------------------+--------+ +|Power Down delay | `gpu_panel_power_down_delay` | T10 | ++----------------------------+---------------------------------------+--------+ +|Backlight off to power down | `gpu_panel_power_backlight_off_delay` | T7 | ++----------------------------+---------------------------------------+--------+ +|Power Cycle Delay | `gpu_panel_power_cycle_delay` | T12 | ++----------------------------+---------------------------------------+--------+ +``` diff --git a/Documentation/gfx/libgfxinit.md b/Documentation/gfx/libgfxinit.md index c50761a..a80291c 100644 --- a/Documentation/gfx/libgfxinit.md +++ b/Documentation/gfx/libgfxinit.md @@ -55,6 +55,9 @@ GMA: Per Board Configuration ----------------------------
+In order to set up the display panel, see the +[specifics for Intel GMA](gfx/intel-gma.md). + There are a few Kconfig symbols to consider. To indicate that a board can initialize graphics through *libgfxinit*:
diff --git a/Documentation/index.md b/Documentation/index.md index 6dbbf4d..8e18f4a 100644 --- a/Documentation/index.md +++ b/Documentation/index.md @@ -173,6 +173,7 @@ * [Dealing with Untrusted Input in SMM](technotes/2017-02-dealing-with-untrusted-input-in-smm.md) * [GPIO toggling in ACPI AML](acpi/gpio.md) * [Native Graphics Initialization with libgfxinit](gfx/libgfxinit.md) +* [Intel GMA specifics](gfx/intel-gma.md) * [Architecture-specific documentation](arch/index.md) * [Northbridge-specific documentation](northbridge/index.md) * [System on Chip-specific documentation](soc/index.md)