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Groups > linux.kernel > #1670787 > unrolled thread
| Started by | Christoph Hellwig <hch@infradead.org> |
|---|---|
| First post | 2017-06-20 15:50 +0200 |
| Last post | 2017-06-22 15:00 +0200 |
| Articles | 4 — 3 participants |
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Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Christoph Hellwig <hch@infradead.org> - 2017-06-20 15:50 +0200
Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Robin Murphy <robin.murphy@arm.com> - 2017-06-20 16:00 +0200
Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Christoph Hellwig <hch@infradead.org> - 2017-06-26 11:40 +0200
Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Vladimir Murzin <vladimir.murzin@arm.com> - 2017-06-22 15:00 +0200
| From | Christoph Hellwig <hch@infradead.org> |
|---|---|
| Date | 2017-06-20 15:50 +0200 |
| Subject | Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree |
| Message-ID | <tUrHB-Q2-47@gated-at.bofh.it> |
Wouldn't the smal patch below solve the same issue in a simple way?
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 640a7e63c453..e8f8447d705b 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -290,9 +290,11 @@ EXPORT_SYMBOL(dma_mmap_from_coherent);
static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
{
struct dma_coherent_mem *mem = rmem->priv;
+ dma_addr_t dev_addr = ((rmem->base >> PAGE_SHIFT) -
+ dev->dma_pfn_offset) << PAGE_SHIFT;
if (!mem &&
- !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
+ !dma_init_coherent_memory(rmem->base, dev_addr, rmem->size,
DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
&mem)) {
pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
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| From | Robin Murphy <robin.murphy@arm.com> |
|---|---|
| Date | 2017-06-20 16:00 +0200 |
| Subject | Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree |
| Message-ID | <tUrRg-Tl-19@gated-at.bofh.it> |
| In reply to | #1670787 |
On 20/06/17 14:42, Christoph Hellwig wrote:
> Wouldn't the smal patch below solve the same issue in a simple way?
That assumes that all devices accessing a shared pool will have the same
dma_pfn_offset as the first one, which cannot strictly be relied upon
(even if it is highly likely in practice).
Robin.
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index 640a7e63c453..e8f8447d705b 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -290,9 +290,11 @@ EXPORT_SYMBOL(dma_mmap_from_coherent);
> static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
> {
> struct dma_coherent_mem *mem = rmem->priv;
> + dma_addr_t dev_addr = ((rmem->base >> PAGE_SHIFT) -
> + dev->dma_pfn_offset) << PAGE_SHIFT;
>
> if (!mem &&
> - !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
> + !dma_init_coherent_memory(rmem->base, dev_addr, rmem->size,
> DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
> &mem)) {
> pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
>
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| From | Christoph Hellwig <hch@infradead.org> |
|---|---|
| Date | 2017-06-26 11:40 +0200 |
| Message-ID | <tWyEX-Ba-35@gated-at.bofh.it> |
| In reply to | #1670791 |
On Tue, Jun 20, 2017 at 02:50:34PM +0100, Robin Murphy wrote: > On 20/06/17 14:42, Christoph Hellwig wrote: > > Wouldn't the smal patch below solve the same issue in a simple way? > > That assumes that all devices accessing a shared pool will have the same > dma_pfn_offset as the first one, which cannot strictly be relied upon > (even if it is highly likely in practice). Which seems like another argument why the global pool should be a different implementation / interface than the per-device dma mapping helpers..
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| From | Vladimir Murzin <vladimir.murzin@arm.com> |
|---|---|
| Date | 2017-06-22 15:00 +0200 |
| Subject | Re: [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree |
| Message-ID | <tV9Si-4Ry-15@gated-at.bofh.it> |
| In reply to | #1670787 |
On 20/06/17 14:42, Christoph Hellwig wrote:
> Wouldn't the smal patch below solve the same issue in a simple way?
>
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index 640a7e63c453..e8f8447d705b 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -290,9 +290,11 @@ EXPORT_SYMBOL(dma_mmap_from_coherent);
> static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
> {
> struct dma_coherent_mem *mem = rmem->priv;
> + dma_addr_t dev_addr = ((rmem->base >> PAGE_SHIFT) -
> + dev->dma_pfn_offset) << PAGE_SHIFT;
>
> if (!mem &&
> - !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
> + !dma_init_coherent_memory(rmem->base, dev_addr, rmem->size,
> DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
> &mem)) {
> pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
>
Robin has already commented on this - dma_pfn_offset may vary across devices
and reserved memory region may be shared between them.
Cheers
Vladimir
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