target/linux/bcm27xx/patches-5.10/950-0508-overlays-Add-pcie-32bit-dma-overlay.patch

   1 From ce2860020c57a59c543139ad7b260624cd930dff Mon Sep 17 00:00:00 2001
   2 From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
   3 Date: Mon, 15 Mar 2021 17:25:02 +0100
   4 Subject: [PATCH] overlays: Add pcie-32bit-dma overlay
   5
   6 In order to accommodate full PCI DMA access to memory on newer BCM2711
   7 revisions, we're forced to map PCIe's view of physical memory with an
   8 offset. This offset makes DMA addressing dependent on having 64bit
   9 support on the PCI device's side. Which isn't always the case.
  10
  11 In order to mitigate this, introduce the pcie-32bit-dma overlay which
  12 will forbid firmware from updating the default inbound memory window.
  13 The default setting, albeit limited to accessing the lower 3GB of
  14 memory, will allow for 32bit DMA addresses at the expense of having to
  15 bounce buffers.
  16
  17 Link: https://github.com/raspberrypi/linux/issues/4197
  18 Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  19 ---
  20  arch/arm/boot/dts/overlays/Makefile            |  1 +
  21  arch/arm/boot/dts/overlays/README              |  7 +++++++
  22  arch/arm/boot/dts/overlays/overlay_map.dts     |  4 ++++
  23  .../dts/overlays/pcie-32bit-dma-overlay.dts    | 18 ++++++++++++++++++
  24  4 files changed, 30 insertions(+)
  25  create mode 100644 arch/arm/boot/dts/overlays/pcie-32bit-dma-overlay.dts
  26
  27 --- a/arch/arm/boot/dts/overlays/Makefile
  28 +++ b/arch/arm/boot/dts/overlays/Makefile
  29 @@ -128,6 +128,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
  30         ov9281.dtbo \
  31         papirus.dtbo \
  32         pca953x.dtbo \
  33 +       pcie-32bit-dma.dtbo \
  34         pibell.dtbo \
  35         pifacedigital.dtbo \
  36         pifi-40.dtbo \
  37 --- a/arch/arm/boot/dts/overlays/README
  38 +++ b/arch/arm/boot/dts/overlays/README
  39 @@ -2135,6 +2135,13 @@ Params: addr                    I2C addr
  40          xra1202                 Select the Exar XRA1202 (8 bit)
  41
  42
  43 +Name:   pcie-32bit-dma
  44 +Info:   Force PCIe config to support 32bit DMA addresses at the expense of
  45 +        having to bounce buffers.
  46 +Load:   dtoverlay=pcie-32bit-dma
  47 +Params: <None>
  48 +
  49 +
  50  [ The pcf2127-rtc overlay has been deleted. See i2c-rtc. ]
  51
  52
  53 --- a/arch/arm/boot/dts/overlays/overlay_map.dts
  54 +++ b/arch/arm/boot/dts/overlays/overlay_map.dts
  55 @@ -37,6 +37,10 @@
  56                 deprecated = "use gpio-ir";
  57         };
  58
  59 +       pcie-32bit-dma {
  60 +               bcm2711;
  61 +       };
  62 +
  63         pi3-act-led {
  64                 renamed = "act-led";
  65         };
  66 --- /dev/null
  67 +++ b/arch/arm/boot/dts/overlays/pcie-32bit-dma-overlay.dts
  68 @@ -0,0 +1,18 @@
  69 +/*
  70 + * pcie-32bit-dma-overlay.dts
  71 + */
  72 +
  73 +/dts-v1/;
  74 +/plugin/;
  75 +
  76 +/ {
  77 +       compatible = "brcm,bcm2711";
  78 +
  79 +       fragment@0 {
  80 +               target-path = "/aliases";
  81 +               __overlay__ {
  82 +                       pcie0 = "";
  83 +               };
  84 +       };
  85 +
  86 +};