Documentation/mainboard/gigabyte/ga-h61m-s2pv: Expand page

Uniformize the Yes/No in the tables, expand the internal programming
section and explain how to patch a defective flash descriptor.

Change-Id: I972bb8948c29ce0eba46daa92ce6b6052db7b063
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/28833
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

1 files changed, 35 insertions, 5 deletions

diff --git a/Documentation/mainboard/gigabyte/ga-h61m-s2pv.md b/Documentation/mainboard/gigabyte/ga-h61m-s2pv.md
index 54c647eef5..06c0ff7e89 100644
--- a/Documentation/mainboard/gigabyte/ga-h61m-s2pv.md
+++ b/Documentation/mainboard/gigabyte/ga-h61m-s2pv.md
@@ -9,13 +9,13 @@ from [Gigabyte].
 +---------------------+------------+
 | Type                | Value      |
 +=====================+============+
-| Socketed flash      | no         |
+| Socketed flash      | No         |
 +---------------------+------------+
 | Model               | MX25L3206E |
 +---------------------+------------+
 | Size                | 4 MiB      |
 +---------------------+------------+
-| In circuit flashing | yes        |
+| In circuit flashing | Yes        |
 +---------------------+------------+
 | Package             | SOIC-8     |
 +---------------------+------------+
@@ -23,13 +23,43 @@ from [Gigabyte].
 +---------------------+------------+
 | Dual BIOS feature   | Yes        |
 +---------------------+------------+
-| Internal flashing   | yes        |
+| Internal flashing   | Yes        |
 +---------------------+------------+
 ```
 
 ### Internal programming
 
-The main SPI flash can be accessed using [flashrom].
+The main SPI flash can be accessed using [flashrom]. The DualBIOS backup flash
+chip is accessible as well using the `dualbiosindex` programmer parameter.
+Since the flash recovery mechanism works even with coreboot installed on the
+main flash chip (it still restores the vendor UEFI though), it is useful to
+leave the backup chip untouched.
+
+### Notes about the original firmware
+
+The original IFD defines the BIOS region as the whole flash chip. While this is
+not an issue if flashing a complete image, it confuses flashrom and trashes the
+flash chip's contents when using the --ifd option. However, this can be easily
+fixed by reading the IFD with flashrom, editing the correct values into it with
+ifdtool and then reflashing it.
+
+Create a layout.txt with the following contents:
+
+	00000000:00000fff fd
+	00180000:003fffff bios
+	00001000:0017ffff me
+
+After that, simply run:
+
+```bash
+sudo flashrom -p internal --ifd -i fd -r ifd.rom
+ifdtool -n layout.txt ifd.rom
+sudo flashrom -p internal --ifd -i fd -w ifd.rom.new
+```
+
+After flashing, power cycle the computer to ensure the new IFD is being used.
+If only a reboot is done, the old IFD layout is still seen by flashrom, even if
+the IFD on the flash chip is correctly defining the new region layout.
 
 ## Technology
 
@@ -43,7 +73,7 @@ The main SPI flash can be accessed using [flashrom].
 +------------------+--------------------------------------------------+
 | SuperIO          | ITE IT8728F                                      |
 +------------------+--------------------------------------------------+
-| EC               |                                                  |
+| EC               | None                                             |
 +------------------+--------------------------------------------------+
 | Coprocessor      | Intel ME                                         |
 +------------------+--------------------------------------------------+