sh: pci: Disable MWI and make pci_dma_burst_advice() a bit more accurate.

None of the SH PCI controllers support MWI, it is always treated as a
direct memory write, so simply disable it outright. In the case of the
PCI cache line size, consult that for the pci_dma_burst_advice()
strategy, and switch over to PCI_DMA_BURST_MULTIPLE, as PPC64.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/pci.h

@@ -89,12 +89,28 @@ static inline void pcibios_penalize_isa_irq(int irq, int active)
 #endif
 
 #ifdef CONFIG_PCI
+/*
+ * None of the SH PCI controllers support MWI, it is always treated as a
+ * direct memory write.
+ */
+#define PCI_DISABLE_MWI
+
 static inline void pci_dma_burst_advice(struct pci_dev *pdev,
 					enum pci_dma_burst_strategy *strat,
 					unsigned long *strategy_parameter)
 {
-	*strat = PCI_DMA_BURST_INFINITY;
-	*strategy_parameter = ~0UL;
+	unsigned long cacheline_size;
+	u8 byte;
+
+	pci_read_config_byte(pdev, PCI_CACHE_LINE_SIZE, &byte);
+
+	if (byte == 0)
+		cacheline_size = L1_CACHE_BYTES;
+	else
+		cacheline_size = byte << 2;
+
+	*strat = PCI_DMA_BURST_MULTIPLE;
+	*strategy_parameter = cacheline_size;
 }
 #endif