add quirk for armv7/sunxi ahci, this is the 'less MD' flavour of the

diff using a flag in softc, instead of at compile-time with #ifdef.

sys/dev/ic/ahci.c

@@ -832,6 +832,14 @@ ahci_port_start(struct ahci_port *ap, int fre_only)
 {
 	u_int32_t			r;
 
+	if (ap->ap_sc->sc_flags & AHCI_F_SUNXI_QUIRK) {
+		/* Setup DMA */
+		r = ahci_pread(ap, AHCI_PREG_SUNXI_DMA);
+		r &= ~AHCI_PREG_SUNXI_DMA_MASK;
+		r |= AHCI_PREG_SUNXI_DMA_INIT; /* XXX if fre_only? */
+		ahci_pwrite(ap, AHCI_PREG_SUNXI_DMA, r);
+	}
+
 	/* XXX FBS: possibly turn FBS on here */
 
 	/* Turn on FRE (and ST) */

sys/dev/ic/ahcireg.h

@@ -224,3 +224,7 @@
 #define AHCI_PREG_FBS_SDE	(1<<2)	/* Single Device Error */
 #define AHCI_PREG_FBS_DEC	(1<<1)	/* Device Error Clear */
 #define AHCI_PREG_FBS_EN	(1<<0)	/* Enable */
+
+#define AHCI_PREG_SUNXI_DMA	0x70 /* Vendor Spec Port DMA for armv7/sunxi */
+#define  AHCI_PREG_SUNXI_DMA_MASK	(0xff<<8)
+#define  AHCI_PREG_SUNXI_DMA_INIT	(0x44<<8)

sys/dev/ic/ahcivar.h

@@ -177,6 +177,7 @@ struct ahci_softc {
 #define AHCI_F_IPMS_PROBE		(1<<1)	/* IPMS on failed PMP probe */
 #define AHCI_F_NO_PMP			(1<<2)	/* ignore PMP capability */
 #define AHCI_F_NO_MSI			(1<<3)	/* disable MSI */
+#define AHCI_F_SUNXI_QUIRK		(1<<4)	/* quirk for armv7/sunxi */
 
 	u_int			sc_ncmds;