[PATCH AUTOSEL 4.19 08/13] parisc: Improve cache flushing for PCXL in arch_sync_dma_for_cpu()

Sasha Levin
2023-05-31T13:53:20Z

From: Helge Deller <deller@gmx.de>

[ Upstream commit 59fa12646d9f56c842b4d5b6418ed77af625c588 ]

Add comment in arch_sync_dma_for_device() and handle the direction flag in
arch_sync_dma_for_cpu().

When receiving data from the device (DMA_FROM_DEVICE) unconditionally
purge the data cache in arch_sync_dma_for_cpu().

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/parisc/kernel/pci-dma.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index 04c48f1ef3fbd..20084336704fc 100644
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -464,13 +464,29 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
size_t size, enum dma_data_direction dir)
{
+ /*
+ * fdc: The data cache line is written back to memory, if and only if
+ * it is dirty, and then invalidated from the data cache.
+ */
flush_kernel_dcache_range((unsigned long)phys_to_virt(paddr), size);
}

void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
size_t size, enum dma_data_direction dir)
{
- flush_kernel_dcache_range((unsigned long)phys_to_virt(paddr), size);
+ unsigned long addr = (unsigned long) phys_to_virt(paddr);
+
+ switch (dir) {
+ case DMA_TO_DEVICE:
+ case DMA_BIDIRECTIONAL:
+ flush_kernel_dcache_range(addr, size);
+ return;
+ case DMA_FROM_DEVICE:
+ purge_kernel_dcache_range_asm(addr, addr + size);
+ return;
+ default:
+ BUG();
+ }
}

void arch_dma_cache_sync(struct device *dev, void *vaddr, size_t size,
--
2.39.2