[PATCH] xtensa: implement arch_dma_coherent_to_pfn

[PATCH] xtensa: implement arch_dma_coherent_to_pfn

[Max Filippov]

Add trivial implementation for arch_dma_coherent_to_pfn.
This change enables communication with PCI ALSA devices through mmapped
buffers.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/Kconfig          | 1 +
 arch/xtensa/kernel/pci-dma.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index bf492f9e1f75..f78e6b6f8b6f 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -3,6 +3,7 @@ config XTENSA
 	def_bool y
 	select ARCH_32BIT_OFF_T
 	select ARCH_HAS_BINFMT_FLAT if !MMU
+	select ARCH_HAS_DMA_COHERENT_TO_PFN
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select ARCH_USE_QUEUED_RWLOCKS
diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index 154979d62b73..6a114ce23084 100644
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -200,3 +200,9 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 	if (!dma_release_from_contiguous(dev, page, count))
 		__free_pages(page, get_order(size));
 }
+
+long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
+			      dma_addr_t dma_addr)
+{
+	return __phys_to_pfn(dma_to_phys(dev, dma_addr));
+}
-- 
2.20.1

Re: [PATCH] xtensa: implement arch_dma_coherent_to_pfn

[Christoph Hellwig]

On Tue, Oct 15, 2019 at 02:25:26PM -0700, Max Filippov wrote:
> Add trivial implementation for arch_dma_coherent_to_pfn.
> This change enables communication with PCI ALSA devices through mmapped
> buffers.

This looks fine, although I'd much rather convert xtensa to the
generic DMA remap / uncached segment support.

Do you want this fix for 5.4?  If so please queue it up ASAP so that
I can do the proper thing for 5.5.  If you don't need it that urgent
I'd rather go straight to the generic code.

Re: [PATCH] xtensa: implement arch_dma_coherent_to_pfn

[Max Filippov]

Hi Christoph,

On Wed, Oct 16, 2019 at 12:08 AM Christoph Hellwig <hch@lst.de> wrote:
> On Tue, Oct 15, 2019 at 02:25:26PM -0700, Max Filippov wrote:
> > Add trivial implementation for arch_dma_coherent_to_pfn.
> > This change enables communication with PCI ALSA devices through mmapped
> > buffers.
>
> This looks fine, although I'd much rather convert xtensa to the
> generic DMA remap / uncached segment support.

Thanks for the review.

> Do you want this fix for 5.4?  If so please queue it up ASAP so that
> I can do the proper thing for 5.5.  If you don't need it that urgent
> I'd rather go straight to the generic code.

There's no rush, I'll keep my version privately and will switch to the
generic version once it's available.

-- 
Thanks.
-- Max