1 From 6dcfc3daab7c1c459b36261163b4e1dc15a6e965 Mon Sep 17 00:00:00 2001
2 From: Phil Elwell <phil@raspberrypi.org>
3 Date: Wed, 3 Feb 2016 16:12:54 +0000
4 Subject: [PATCH 141/170] BCM270X_DT: Disable DMA for bcm2835-sdhost on Pi2
6 This is an interim patch to verify that problems seen with
7 some cards can be worked around at the expense of an increased
8 CPU load by forcing PIO mode.
10 Although this could have used the brcm,force-pio attribute, that
11 is a boolean (true if present, false if absent) and attributes
12 can't be deleted by overlays. Instead, make brcm,pio-limit
13 unfeasibly high instead to allow DMA to be re-enabled using the
14 pio_limit parameter of the sdhost or sdtweak overlays.
16 arch/arm/boot/dts/bcm2709-rpi-2-b.dts | 1 +
17 1 file changed, 1 insertion(+)
19 --- a/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
20 +++ b/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
22 pinctrl-names = "default";
23 pinctrl-0 = <&sdhost_pins>;
25 + brcm,pio-limit = <0x7fffffff>;