efi/gop: Allow specifying mode number on command line
Add the ability to choose a video mode for the selected gop by using a
command-line argument of the form
video=efifb:mode=<n>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200320020028.1936003-12-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
diff --git a/Documentation/fb/efifb.rst b/Documentation/fb/efifb.rst
index 04840331a..367fbda 100644
--- a/Documentation/fb/efifb.rst
+++ b/Documentation/fb/efifb.rst
@@ -2,8 +2,10 @@
What is efifb?
==============
-This is a generic EFI platform driver for Intel based Apple computers.
-efifb is only for EFI booted Intel Macs.
+This is a generic EFI platform driver for systems with UEFI firmware. The
+system must be booted via the EFI stub for this to be usable. efifb supports
+both firmware with Graphics Output Protocol (GOP) displays as well as older
+systems with only Universal Graphics Adapter (UGA) displays.
Supported Hardware
==================
@@ -12,11 +14,14 @@
- Macbook
- Macbook Pro 15"/17"
- MacMini
+- ARM/ARM64/X86 systems with UEFI firmware
How to use it?
==============
-efifb does not have any kind of autodetection of your machine.
+For UGA displays, efifb does not have any kind of autodetection of your
+machine.
+
You have to add the following kernel parameters in your elilo.conf::
Macbook :
@@ -28,6 +33,9 @@
Macbook Pro 17", iMac 20" :
video=efifb:i20
+For GOP displays, efifb can autodetect the display's resolution and framebuffer
+address, so these should work out of the box without any special parameters.
+
Accepted options:
======= ===========================================================
@@ -36,4 +44,10 @@
when large amounts of console data are written.
======= ===========================================================
+Options for GOP displays:
+
+mode=n
+ The EFI stub will set the mode of the display to mode number n if
+ possible.
+
Edgar Hucek <gimli@dark-green.com>
