From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Mon, 19 Jan 2015 17:09:05 +0000 (-0800)
Subject: kernel - limit DMA for older ALI chips to 256KB
X-Git-Tag: v4.2.0rc~1040
X-Git-Url: https://gitweb.dragonflybsd.org/~tuxillo/dragonfly.git/commitdiff_plain/44de769701873813cb3ad7234931903522533e9f

kernel - limit DMA for older ALI chips to 256KB

* For ancient machines using old ALI chipsets which do
  not support 48-bit DMA, also limit the maximum DMA
  size to 256KB.
---

diff --git a/sys/dev/disk/nata/ata-chipset.c b/sys/dev/disk/nata/ata-chipset.c
index 4401053092..954858000b 100644
--- a/sys/dev/disk/nata/ata-chipset.c
+++ b/sys/dev/disk/nata/ata-chipset.c
@@ -1166,8 +1166,11 @@ ata_ali_allocate(device_t dev)
 	return ENXIO;
 
     /* older chips can't do 48bit DMA transfers */
-    if (ctlr->chip->chiprev <= 0xc4)
+    if (ctlr->chip->chiprev <= 0xc4) {
 	ch->flags |= ATA_NO_48BIT_DMA;
+	if (ch->dma->max_iosize > 256 * 512)
+		ch->dma->max_iosize = 256 * 512;
+    }
 
     return 0;
 }