Hi Arnd,
On Mon, Mar 27, 2023 at 2:16 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>
The arm version of the arch_sync_dma_for_cpu() function annotates pages as
PG_dcache_clean after a DMA, but no other architecture does this here. On
ia64, the same thing is done in arch_sync_dma_for_cpu(), so it makes sense
to use the same hook in order to have identical arch_sync_dma_for_cpu()
semantics as all other architectures.
Splitting this out has multiple effects:
- for dma-direct, this now gets called after arch_sync_dma_for_cpu()
for DMA_FROM_DEVICE mappings, but not for DMA_BIDIRECTIONAL. While
it would not be harmful to keep doing it for bidirectional mappings,
those are apparently not used in any callers that care about the flag.
- Since arm has its own dma-iommu abstraction, this now also needs to
call the same function, so the calls are added there to mirror the
dma-direct version.
- Like dma-direct, the dma-iommu version now marks the dcache clean
for both coherent and noncoherent devices after a DMA, but it only
does this for DMA_FROM_DEVICE, not DMA_BIDIRECTIONAL.
[ HELP NEEDED: can anyone confirm that it is a correct assumption
on arm that a cache-coherent device writing to a page always results
in it being in a PG_dcache_clean state like on ia64, or can a device
write directly into the dcache?]
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Thanks for your patch, which is now commit 322dbe898f82fd8a
("ARM: dma-mapping: split out arch_dma_mark_clean() helper") in
esmil/jh7100-dmapool.
If CONFIG_ARM_DMA_USE_IOMMU=y, the build fails.
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1294,6 +1298,17 @@ static int arm_iommu_map_sg(struct device *dev, struct scatterlist *sg,
return -EINVAL;
}
+static void arm_iommu_sync_dma_for_cpu(phys_addr_t phys, size_t len,
+ enum dma_data_direction dir,
+ bool dma_coherent)
+{
+ if (!dma_coherent)
+ arch_sync_dma_for_cpu(phys, s->length, dir);
s/s->length/len/
+
+ if (dir == DMA_FROM_DEVICE)
+ arch_dma_mark_clean(phys, s->length);
Likewise.
+}
+
/**
* arm_iommu_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
* @dev: valid struct device pointer
@@ -1425,9 +1438,9 @@ static void arm_iommu_unmap_page(struct device *dev, dma_addr_t handle,
if (!iova)
return;
- if (!dev->dma_coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) {
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
Missing opening curly brace.
phys = iommu_iova_to_phys(mapping->domain, handle);
- arch_sync_dma_for_cpu(phys, size, dir);
+ arm_iommu_sync_dma_for_cpu(phys, size, dir, dev->dma_coherent);
}
iommu_unmap(mapping->domain, iova, len);
With the above fixed, it builds and boots fine (on R-Car M2-W).
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
