Re: new SBus related DMA warnings in 4.18+git

Christoph Hellwig
2018-08-27T15:47:16Z

On Sun, Aug 26, 2018 at 10:48:44AM +0300, Meelis Roos wrote:
> Tried yesterdays git 4.18.0-12789-gaa5b105 on a Sun Ultra 1 with SBus
> and several SBus connected devicess give DMA mapping related warnings:

This should have been around since the warning was added.

The patch below should fix it:

---
>From 6294e0e330851ee06e66ab85b348f1d92d375d7a 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..d84ec1de6022 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;
+ dma_addr_t dma_mask;
u32 num_resources;
struct resource *resource;

--
2.18.0