MIPS: Alchemy: Determine cohereny at runtime based on cpu type

All Alchemy chips have coherent DMA, but for example the USB or AC97
peripherals on the Au1000/1500/1100 are not.
This patch uses DMA_MAYBE_COHERENT on Alchemy and sets coherentio based
on CPU type.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/6576/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/mips/pci/pci-alchemy.c b/arch/mips/pci/pci-alchemy.c
index d1faece21b6a..563d1f61d6ee 100644
--- a/arch/mips/pci/pci-alchemy.c
+++ b/arch/mips/pci/pci-alchemy.c
@@ -16,6 +16,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/vmalloc.h>
 
+#include <asm/dma-coherence.h>
 #include <asm/mach-au1x00/au1000.h>
 #include <asm/tlbmisc.h>
 
@@ -411,17 +412,15 @@ static int alchemy_pci_probe(struct platform_device *pdev)
         }
         ctx->alchemy_pci_ctrl.io_map_base = (unsigned long)virt_io;
 
-#ifdef CONFIG_DMA_NONCOHERENT
         /* Au1500 revisions older than AD have borked coherent PCI */
         if ((alchemy_get_cputype() == ALCHEMY_CPU_AU1500) &&
-            (read_c0_prid() < 0x01030202)) {
+            (read_c0_prid() < 0x01030202) && !coherentio) {
                 val = __raw_readl(ctx->regs + PCI_REG_CONFIG);
                 val |= PCI_CONFIG_NC;
                 __raw_writel(val, ctx->regs + PCI_REG_CONFIG);
                 wmb();
                 dev_info(&pdev->dev, "non-coherent PCI on Au1500 AA/AB/AC\n");
         }
-#endif
 
         if (pd->board_map_irq)
                 ctx->board_map_irq = pd->board_map_irq;