Hi Will,
On 14/11/14 18:56, Will Deacon wrote:
of_dma_configure determines the size of the DMA range for a device by
either parsing the dma-ranges property or inspecting the coherent DMA
mask. This same information can be used to initialise the max segment
size and boundary_mask to a default value.
Signed-off-by: Will Deacon <will.dea...@arm.com>
Sadly, NAK on this one. After a thorough investigation and testing,
generic code really shouldn't be touching dma_parms like this, and I
have some corrupted files on my USB filesystem to prove it ;) It seems
it's a bad idea to effectively change the default segment size
universally unless you really want to go through the entire block layer
(and who-knows-what-else) to find and fix everything that relies on it
being 64k.
Simply dropping this patch and letting the existing defaults in
dma_set_max_seg_size and dma_get_seg_boundary stand seems like the
correct action.
Marek, I believe you may have some use case for this - if so, as I
understand it your individual drivers should be setting up their own
dma_parms directly, to tell the IOMMU they can handle it merging
scatterlists into arbitrarily long segments, without affecting the other
drivers that assume they'll never see >64k segments and go wrong if they
do (including the generic USB stack, apparently).
Robin.
---
drivers/of/platform.c | 4 ++++
include/linux/amba/bus.h | 1 +
include/linux/platform_device.h | 2 ++
3 files changed, 7 insertions(+)
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index b89caf8c7586..0a2842d91db4 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -191,6 +191,8 @@ static void of_dma_configure(struct device *dev)
dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
}
dev->dma_pfn_offset = offset;
+ dma_set_max_seg_size(dev, size);
+ dma_set_seg_boundary(dev, size);
coherent = of_dma_is_coherent(dev->of_node);
dev_dbg(dev, "device is%sdma coherent\n",
@@ -236,6 +238,7 @@ static struct platform_device
*of_platform_device_create_pdata(
dev->dev.bus = &platform_bus_type;
dev->dev.platform_data = platform_data;
+ dev->dev.dma_parms = &dev->dma_parms;
of_dma_configure(&dev->dev);
if (of_device_add(dev) != 0) {
@@ -295,6 +298,7 @@ static struct amba_device *of_amba_device_create(struct
device_node *node,
dev->dev.of_node = of_node_get(node);
dev->dev.parent = parent;
dev->dev.platform_data = platform_data;
+ dev->dev.dma_parms = &dev->dma_parms;
if (bus_id)
dev_set_name(&dev->dev, "%s", bus_id);
else
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index c324f5700d1a..9b232eeb6c20 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -32,6 +32,7 @@ struct amba_device {
struct clk *pclk;
unsigned int periphid;
unsigned int irq[AMBA_NR_IRQS];
+ struct device_dma_parameters dma_parms;
};
struct amba_driver {
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 153d303af7eb..8dc48487b34b 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -27,6 +27,8 @@ struct platform_device {
u32 num_resources;
struct resource *resource;
+ struct device_dma_parameters dma_parms;
+
const struct platform_device_id *id_entry;
char *driver_override; /* Driver name to force a match */
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