X-Git-Url: https://git.stricted.de/?a=blobdiff_plain;f=drivers%2Fdma%2Fioat_dca.c;h=78705ca7d36a9e27caf103a0a45ce5cbb4fadd1c;hb=8b794b141c633083408d0bfb2229b3406d0ebf99;hp=6cf622da0286481fccb32a73285c72c83fb6a57b;hpb=f68ec0c24755e5cdb779be6240925f2175311d84;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git

diff --git a/drivers/dma/ioat_dca.c b/drivers/dma/ioat_dca.c
index 6cf622da0286..78705ca7d36a 100644
--- a/drivers/dma/ioat_dca.c
+++ b/drivers/dma/ioat_dca.c
@@ -49,6 +49,23 @@
 
 #define DCA_TAG_MAP_MASK 0xDF
 
+/* expected tag map bytes for I/OAT ver.2 */
+#define DCA2_TAG_MAP_BYTE0 0x80
+#define DCA2_TAG_MAP_BYTE1 0x0
+#define DCA2_TAG_MAP_BYTE2 0x81
+#define DCA2_TAG_MAP_BYTE3 0x82
+#define DCA2_TAG_MAP_BYTE4 0x82
+
+/* verify if tag map matches expected values */
+static inline int dca2_tag_map_valid(u8 *tag_map)
+{
+	return ((tag_map[0] == DCA2_TAG_MAP_BYTE0) &&
+		(tag_map[1] == DCA2_TAG_MAP_BYTE1) &&
+		(tag_map[2] == DCA2_TAG_MAP_BYTE2) &&
+		(tag_map[3] == DCA2_TAG_MAP_BYTE3) &&
+		(tag_map[4] == DCA2_TAG_MAP_BYTE4));
+}
+
 /*
  * "Legacy" DCA systems do not implement the DCA register set in the
  * I/OAT device.  Software needs direct support for their tag mappings.
@@ -452,6 +469,13 @@ struct dca_provider *ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 			ioatdca->tag_map[i] = 0;
 	}
 
+	if (!dca2_tag_map_valid(ioatdca->tag_map)) {
+		dev_err(&pdev->dev, "APICID_TAG_MAP set incorrectly by BIOS, "
+			"disabling DCA\n");
+		free_dca_provider(dca);
+		return NULL;
+	}
+
 	err = register_dca_provider(dca, &pdev->dev);
 	if (err) {
 		free_dca_provider(dca);