Change in ...coreboot[master]: Documentation: libgfxinit timing parameters

[Daniel Maslowski (Code Review)]

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 
---
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)

[Nico Huber (Code Review)]

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: libgfxinit timing parameters
......................................................................

Patch Set 1: Code-Review+1

(2 comments)

Just two small comments...

Please make sure that the `Change-Id` is kept in the
commit message. Last resort, copy it manually.

https://review.coreboot.org/#/c/33265/1//COMMIT_MSG 
Commit Message:

https://review.coreboot.org/#/c/33265/1//COMMIT_MSG@7 
PS1, Line 7: libgfxinit timing parameters
This should be an imperative statement, e.g. `Add Intel GMA timing parameters`

https://review.coreboot.org/#/c/33265/1/Documentation/gfx/intel-gma.md 
File Documentation/gfx/intel-gma.md:

https://review.coreboot.org/#/c/33265/1/Documentation/gfx/intel-gma.md@27 
PS1, Line 27: Haswell
AIUI, this numbering is `eDP` specific (not platform specific).

Change in ...coreboot[master]: Documentation: Add Intel GMA timing parameters

[Daniel Maslowski (Code Review)]

Hello build bot (Jenkins), Nico Huber,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/33265

to look at the new patch set (#2).

Change subject: Documentation: Add Intel GMA timing parameters
......................................................................

Documentation: Add Intel GMA timing parameters

Change-Id: If1a393578556d51499c700b68187034830d19215
Signed-off-by: Daniel Maslowski 
---
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/65/33265/2

Change in ...coreboot[master]: Documentation: Add Intel GMA timing parameters

[Daniel Maslowski (Code Review)]

Daniel Maslowski has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add Intel GMA timing parameters
......................................................................

Patch Set 2:

(1 comment)

https://review.coreboot.org/#/c/33265/1//COMMIT_MSG 
Commit Message:

https://review.coreboot.org/#/c/33265/1//COMMIT_MSG@7 
PS1, Line 7: libgfxinit timing parameters
> This should be an imperative statement, e.g. […]

Ack

Change in ...coreboot[master]: Documentation: Add Intel GMA timing parameters

[Daniel Maslowski (Code Review)]

Hello build bot (Jenkins), Nico Huber,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/33265

to look at the new patch set (#3).

Change subject: Documentation: Add Intel GMA timing parameters
......................................................................

Documentation: Add Intel GMA timing parameters

Change-Id: If1a393578556d51499c700b68187034830d19215
Signed-off-by: Daniel Maslowski 
---
A Documentation/gfx/intel-gma.md
M Documentation/gfx/libgfxinit.md
M Documentation/index.md
3 files changed, 53 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/65/33265/3

Change in ...coreboot[master]: Documentation: Add Intel GMA timing parameters

[Nico Huber (Code Review)]

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add Intel GMA timing parameters
......................................................................

Patch Set 3: Code-Review+2

Change in ...coreboot[master]: Documentation: Add Intel GMA timing parameters

[Felix Held (Code Review)]

Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add Intel GMA timing parameters
......................................................................

Patch Set 3:

the timing parameters are more about the panel than about the Intel GMA. the content itself looks good though

Change in ...coreboot[master]: Documentation: Add display panel specifics

[Daniel Maslowski (Code Review)]

Hello build bot (Jenkins), Nico Huber,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/33265

to look at the new patch set (#4).

Change subject: Documentation: Add display panel specifics
......................................................................

Documentation: Add display panel specifics

Change-Id: If1a393578556d51499c700b68187034830d19215
Signed-off-by: Daniel Maslowski 
---
A Documentation/gfx/display-panel.md
M Documentation/gfx/libgfxinit.md
M Documentation/index.md
3 files changed, 68 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/65/33265/4

Change in ...coreboot[master]: Documentation: Add display panel specifics

[Felix Held (Code Review)]

Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add display panel specifics
......................................................................

Patch Set 4: Code-Review+1

Change in ...coreboot[master]: Documentation: Add display panel specifics

[Nico Huber (Code Review)]

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add display panel specifics
......................................................................

Patch Set 4: Code-Review+2

Change in ...coreboot[master]: Documentation: Add display panel specifics

[Nico Huber (Code Review)]

Nico Huber has submitted this change and it was merged. ( https://review.coreboot.org/c/coreboot/+/33265 )

Change subject: Documentation: Add display panel specifics
......................................................................

Documentation: Add display panel specifics

Change-Id: If1a393578556d51499c700b68187034830d19215
Signed-off-by: Daniel Maslowski 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33265
Tested-by: build bot (Jenkins) 
Reviewed-by: Felix Held 
Reviewed-by: Nico Huber 
---
A Documentation/gfx/display-panel.md
M Documentation/gfx/libgfxinit.md
M Documentation/index.md
3 files changed, 68 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Nico Huber: Looks good to me, approved
  Felix Held: Looks good to me, but someone else must approve

diff --git a/Documentation/gfx/display-panel.md b/Documentation/gfx/display-panel.md
new file mode 100644
index 0000000..3bab089
--- /dev/null
+++ b/Documentation/gfx/display-panel.md
@@ -0,0 +1,64 @@
+Display Panel 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                         | eDP |
++-----------------------------+---------------------------------------+-----+
+| 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` | T9  |
++-----------------------------+---------------------------------------+-----+
+| Power Cycle Delay           | `gpu_panel_power_cycle_delay`         | T12 |
++-----------------------------+---------------------------------------+-----+
+```
+
+Intel GPU Tools and VBT
+-----------------------
+
+The Intel GPU tools are in a package called either `intel-gpu-tools` or
+`igt-gpu-tools` in most distributions of Linux-based operating systems.
+In the coreboot `util/` directory, you can find `intelvbttool`.
+
+From a running system, you can dump the register values directly:
+```sh
+$ intel_reg dump --all | grep PCH_PP
+                      PCH_PP_STATUS (0x000c7200): 0x80000008
+                     PCH_PP_CONTROL (0x000c7204): 0x00000007
+                   PCH_PP_ON_DELAYS (0x000c7208): 0x07d00001
+                  PCH_PP_OFF_DELAYS (0x000c720c): 0x01f40001
+                     PCH_PP_DIVISOR (0x000c7210): 0x0004af06
+```
+
+You can obtain the timing values from a VBT (Video BIOS Table), which you can
+dump from a vendor UEFI image:
+```sh
+$ intel_vbt_decode data.vbt | grep T3
+                Power Sequence: T3 2000 T7 10 T9 2000 T10 500 T12 5000
+                T3 optimization: no
+```
diff --git a/Documentation/gfx/libgfxinit.md b/Documentation/gfx/libgfxinit.md
index c50761a..c000f27 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
+[display panel-specific documentation](/gfx/display-panel.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..76faffa 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)
+* [Display panel-specific documentation](gfx/display-panel.md)
 * [Architecture-specific documentation](arch/index.md)
 * [Northbridge-specific documentation](northbridge/index.md)
 * [System on Chip-specific documentation](soc/index.md)