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87 lines
2.5 KiB
Diff
87 lines
2.5 KiB
Diff
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From ce2860020c57a59c543139ad7b260624cd930dff Mon Sep 17 00:00:00 2001
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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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Date: Mon, 15 Mar 2021 17:25:02 +0100
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Subject: [PATCH] overlays: Add pcie-32bit-dma overlay
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In order to accommodate full PCI DMA access to memory on newer BCM2711
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revisions, we're forced to map PCIe's view of physical memory with an
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offset. This offset makes DMA addressing dependent on having 64bit
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support on the PCI device's side. Which isn't always the case.
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In order to mitigate this, introduce the pcie-32bit-dma overlay which
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will forbid firmware from updating the default inbound memory window.
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The default setting, albeit limited to accessing the lower 3GB of
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memory, will allow for 32bit DMA addresses at the expense of having to
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bounce buffers.
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Link: https://github.com/raspberrypi/linux/issues/4197
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Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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---
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arch/arm/boot/dts/overlays/Makefile | 1 +
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arch/arm/boot/dts/overlays/README | 7 +++++++
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arch/arm/boot/dts/overlays/overlay_map.dts | 4 ++++
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.../dts/overlays/pcie-32bit-dma-overlay.dts | 18 ++++++++++++++++++
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4 files changed, 30 insertions(+)
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create mode 100644 arch/arm/boot/dts/overlays/pcie-32bit-dma-overlay.dts
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--- a/arch/arm/boot/dts/overlays/Makefile
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+++ b/arch/arm/boot/dts/overlays/Makefile
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@@ -128,6 +128,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
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ov9281.dtbo \
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papirus.dtbo \
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pca953x.dtbo \
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+ pcie-32bit-dma.dtbo \
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pibell.dtbo \
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pifacedigital.dtbo \
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pifi-40.dtbo \
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--- a/arch/arm/boot/dts/overlays/README
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+++ b/arch/arm/boot/dts/overlays/README
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@@ -2135,6 +2135,13 @@ Params: addr I2C addr
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xra1202 Select the Exar XRA1202 (8 bit)
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+Name: pcie-32bit-dma
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+Info: Force PCIe config to support 32bit DMA addresses at the expense of
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+ having to bounce buffers.
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+Load: dtoverlay=pcie-32bit-dma
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+Params: <None>
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+
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+
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[ The pcf2127-rtc overlay has been deleted. See i2c-rtc. ]
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--- a/arch/arm/boot/dts/overlays/overlay_map.dts
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+++ b/arch/arm/boot/dts/overlays/overlay_map.dts
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@@ -37,6 +37,10 @@
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deprecated = "use gpio-ir";
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};
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+ pcie-32bit-dma {
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+ bcm2711;
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+ };
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+
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pi3-act-led {
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renamed = "act-led";
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};
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--- /dev/null
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+++ b/arch/arm/boot/dts/overlays/pcie-32bit-dma-overlay.dts
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@@ -0,0 +1,18 @@
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+/*
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+ * pcie-32bit-dma-overlay.dts
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+ */
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+
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+/dts-v1/;
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+/plugin/;
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+
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+/ {
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+ compatible = "brcm,bcm2711";
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+
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+ fragment@0 {
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+ target-path = "/aliases";
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+ __overlay__ {
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+ pcie0 = "";
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+ };
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+ };
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+
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+};
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