target/linux/brcm2708/patches-4.4/0141-BCM270X_DT-Disable-DMA-for-bcm2835-sdhost-on-Pi2.patch

   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
   5
   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.
   9
  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.
  15 ---
  16  arch/arm/boot/dts/bcm2709-rpi-2-b.dts | 1 +
  17  1 file changed, 1 insertion(+)
  18
  19 --- a/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
  20 +++ b/arch/arm/boot/dts/bcm2709-rpi-2-b.dts
  21 @@ -43,6 +43,7 @@
  22         pinctrl-names = "default";
  23         pinctrl-0 = <&sdhost_pins>;
  24         bus-width = <4>;
  25 +       brcm,pio-limit = <0x7fffffff>;
  26         status = "okay";
  27  };
  28