Re: new SBus related DMA warnings in 4.18+git

Christoph Hellwig
2018-08-28T11:43:58Z

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Updated version including that has survived contact with a sparc cross
compiler below. Note that this is on top of the previous patch adding
a dma_mask to struct platform_device, which I've included as well.

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>From e22d27b9bf48c0e3d6eb106f596972c9357ed24d Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Date: Mon, 27 Aug 2018 17:23:24 +0200
Subject: driver core: initialize a default DMA mask for platform device

We still treat devices without a DMA mask as defaulting to 32-bits for
both mask, but a few releases ago we've started warning about such
cases, as they require special cases to work around this sloppyness.
Add a dma_mask field to struct platform_object so that we can initialize
the dma_mask pointer in struct device and initialize both masks to
32-bits by default. Architectures can still override this in
arch_setup_pdev_archdata if needed.

Note that the code looks a little odd with the various conditionals
because we have to support platform_device structures that are
statically allocated.

Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
---
drivers/base/platform.c | 15 +++++++++++++--
include/linux/platform_device.h | 1 +
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index dff82a3c2caa..baf4b06cf2d9 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -225,6 +225,17 @@ struct platform_object {
char name[];
};

+static void setup_pdev_archdata(struct platform_device *pdev)
+{
+ if (!pdev->dev.coherent_dma_mask)
+ pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+ if (!pdev->dma_mask)
+ pdev->dma_mask = DMA_BIT_MASK(32);
+ if (!pdev->dev.dma_mask)
+ pdev->dev.dma_mask = &pdev->dma_mask;
+ arch_setup_pdev_archdata(pdev);
+};
+
/**
* platform_device_put - destroy a platform device
* @pdev: platform device to free
@@ -271,7 +282,7 @@ struct platform_device *platform_device_alloc(const char *name, int id)
pa->pdev.id = id;
device_initialize(&pa->pdev.dev);
pa->pdev.dev.release = platform_device_release;
- arch_setup_pdev_archdata(&pa->pdev);
+ setup_pdev_archdata(&pa->pdev);
}

return pa ? &pa->pdev : NULL;
@@ -472,7 +483,7 @@ EXPORT_SYMBOL_GPL(platform_device_del);
int platform_device_register(struct platform_device *pdev)
{
device_initialize(&pdev->dev);
- arch_setup_pdev_archdata(pdev);
+ setup_pdev_archdata(pdev);
return platform_device_add(pdev);
}
EXPORT_SYMBOL_GPL(platform_device_register);
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 1a9f38f27f65..d9dc4883d5fb 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -25,6 +25,7 @@ struct platform_device {
int id;
bool id_auto;
struct device dev;
+ u64 dma_mask;
u32 num_resources;
struct resource *resource;

--
2.18.0

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>From b4c6e6779559a1bcda41fad0f2e8b713fcf96446 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Date: Tue, 28 Aug 2018 11:25:51 +0200
Subject: sparc: set a default 32-bit dma mask for OF devices

This keeps the historic default behavior for devices without a DMA mask,
but removes the warning about a lacking DMA mask for doing DMA without
a mask.

Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
---
arch/sparc/kernel/of_device_32.c | 5 +++++
arch/sparc/kernel/of_device_64.c | 4 ++++
2 files changed, 9 insertions(+)

diff --git a/arch/sparc/kernel/of_device_32.c b/arch/sparc/kernel/of_device_32.c
index 3641a294ed54..7f3dec7e1e78 100644
--- a/arch/sparc/kernel/of_device_32.c
+++ b/arch/sparc/kernel/of_device_32.c
@@ -9,6 +9,7 @@
#include <linux/irq.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
+#include <linux/dma-mapping.h>
#include <asm/leon.h>
#include <asm/leon_amba.h>

@@ -381,6 +382,10 @@ static struct platform_device * __init scan_one_device(struct device_node *dp,
else
dev_set_name(&op->dev, "%08x", dp->phandle);

+ op->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+ op->dev.dma_mask = &op->dma_mask;
+ op->dma_mask = DMA_BIT_MASK(32);
+
if (of_device_register(op)) {
printk("%s: Could not register of device.\n",
dp->full_name);
diff --git a/arch/sparc/kernel/of_device_64.c b/arch/sparc/kernel/of_device_64.c
index 44e4d4435bed..d94c31822da1 100644
--- a/arch/sparc/kernel/of_device_64.c
+++ b/arch/sparc/kernel/of_device_64.c
@@ -2,6 +2,7 @@
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/of.h>
+#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/mod_devicetable.h>
@@ -675,6 +676,9 @@ static struct platform_device * __init scan_one_device(struct device_node *dp,
dev_set_name(&op->dev, "root");
else
dev_set_name(&op->dev, "%08x", dp->phandle);
+ op->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+ op->dev.dma_mask = &op->dma_mask;
+ op->dma_mask = DMA_BIT_MASK(32);

if (of_device_register(op)) {
printk("%s: Could not register of device.\n",
--
2.18.0

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