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From 017f788741107824346784a5f342b88013f885d0 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Fri, 19 Apr 2024 11:35:41 +0100
Subject: [PATCH 1038/1085] overlays/README: Document that vc4-(f)kms requires
>=512MB
The firmware stops vc4-kms-v3d and vc4-fkms-v3d loading if the
system has less than 512MB of RAM. It can work if gpu_mem and
CMA heap size are set appropriately, but can't be guaranteed.
Document this restriction.
Also drops Eric's name from the overlay description as it
isn't relevant or accurate anymore.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
arch/arm/boot/dts/overlays/README | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -4864,8 +4864,10 @@ Params: <None>
Name: vc4-fkms-v3d
-Info: Enable Eric Anholt's DRM VC4 V3D driver on top of the dispmanx
+Info: Enable the kernel DRM VC4 V3D driver on top of the dispmanx
display stack.
+ NB The firmware will not allow this overlay to load on a Pi with less
+ than 512MB as memory is too tight.
Load: dtoverlay=vc4-fkms-v3d,<param>
Params: cma-512 CMA is 512MB (needs 1GB)
cma-448 CMA is 448MB (needs 1GB)
@@ -4881,7 +4883,7 @@ Params: cma-512 CMA is 5
Name: vc4-fkms-v3d-pi4
-Info: Enable Eric Anholt's DRM VC4 V3D driver on top of the dispmanx
+Info: Enable the kernel DRM VC4 V3D driver on top of the dispmanx
display stack.
Load: dtoverlay=vc4-fkms-v3d-pi4,<param>
Params: cma-512 CMA is 512MB (needs 1GB)
@@ -5150,7 +5152,9 @@ Load: <Deprecated>
Name: vc4-kms-v3d
-Info: Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver.
+Info: Enable the kernel DRM VC4 HDMI/HVS/V3D driver.
+ NB The firmware will not allow this overlay to load on a Pi with less
+ than 512MB as memory is too tight.
Load: dtoverlay=vc4-kms-v3d,<param>
Params: cma-512 CMA is 512MB (needs 1GB)
cma-448 CMA is 448MB (needs 1GB)
@@ -5171,7 +5175,7 @@ Params: cma-512 CMA is 5
Name: vc4-kms-v3d-pi4
-Info: Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver for Pi4.
+Info: Enable the kernel DRM VC4 HDMI/HVS/V3D driver for Pi4.
Load: dtoverlay=vc4-kms-v3d-pi4,<param>
Params: cma-512 CMA is 512MB
cma-448 CMA is 448MB
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