parisc: Improve cache flushing for PCXL in arch_sync_dma_for_cpu()

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>

diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index ba87f791323be008d1e6abfcfbe846a55575cbf5..71ed5391f29d6f00ec85168b02cce2fe4eccb097 100644 (file)
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -446,11 +446,27 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 void arch_sync_dma_for_device(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(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();
+       }
 }