openwrtv4/target/linux/brcm2708/patches-4.4/0141-BCM270X_DT-Disable-DMA-for-bcm2835-sdhost-on-Pi2.patch
John Crispin b3dc9566a4 brcm2708: switch to linux 4.4 and update patches
As usual these patches were extracted from:
https://github.com/raspberrypi/linux/commits/rpi-4.4.y

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

SVN-Revision: 48765
2016-02-25 10:14:01 +00:00

28 lines
1,008 B
Diff

From 403252ab4bc6c77f2859410e6fa22f3c2bded3e5 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Wed, 3 Feb 2016 16:12:54 +0000
Subject: [PATCH 141/156] BCM270X_DT: Disable DMA for bcm2835-sdhost on Pi2
This is an interim patch to verify that problems seen with
some cards can be worked around at the expense of an increased
CPU load by forcing PIO mode.
Although this could have used the brcm,force-pio attribute, that
is a boolean (true if present, false if absent) and attributes
can't be deleted by overlays. Instead, make brcm,pio-limit
unfeasibly high instead to allow DMA to be re-enabled using the
pio_limit parameter of the sdhost or sdtweak overlays.
---
arch/arm/boot/dts/bcm2709-rpi-2-b.dts | 1 +
1 file changed, 1 insertion(+)
--- a/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
+++ b/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
@@ -43,6 +43,7 @@
pinctrl-names = "default";
pinctrl-0 = <&sdhost_pins>;
bus-width = <4>;
+ brcm,pio-limit = <0x7fffffff>;
status = "okay";
};