pata_cs5536: add quirk for broken udma

I am working on a device which uses the cs5536 pata driver. There
are some broken hardware revisions out in the field, which can be
detected via DMI. On older versions with an embedded BIOS I
used libata.dma=0 to disable dma completely.
Now we are switching to a coreboot/seabios based BIOS where we
have DMI support and so I think its a good idea to get rid of
all those hacky kernel parameters as the same image
is used other devices where libata.dma=0 is not a good idea.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/ata/pata_cs5536.c b/drivers/ata/pata_cs5536.c
index dec1b6c4b351244b4da8326d982f4c3bd859fec4..0448860a2077526cea30354fc60b6c6c3cacada9 100644 (file)
--- a/drivers/ata/pata_cs5536.c
+++ b/drivers/ata/pata_cs5536.c
@@ -38,6 +38,7 @@
 #include <linux/delay.h>
 #include <linux/libata.h>
 #include <scsi/scsi_host.h>
+#include <linux/dmi.h>
 
 #ifdef CONFIG_X86_32
 #include <asm/msr.h>
@@ -80,6 +81,21 @@ enum {
        IDE_ETC_UDMA_MASK       = 0xc0,
 };
 
+/* Some Bachmann OT200 devices have a non working UDMA support due a
+ * missing resistor.
+ */
+static const struct dmi_system_id udma_quirk_dmi_table[] = {
+       {
+               .ident = "Bachmann electronic OT200",
+               .matches = {
+                       DMI_MATCH(DMI_SYS_VENDOR, "Bachmann electronic"),
+                       DMI_MATCH(DMI_PRODUCT_NAME, "OT200"),
+                       DMI_MATCH(DMI_PRODUCT_VERSION, "1")
+               },
+       },
+       { }
+};
+
 static int cs5536_read(struct pci_dev *pdev, int reg, u32 *val)
 {
        if (unlikely(use_msr)) {
@@ -242,9 +258,23 @@ static int cs5536_init_one(struct pci_dev *dev, const struct pci_device_id *id)
                .port_ops = &cs5536_port_ops,
        };
 
-       const struct ata_port_info *ppi[] = { &info, &ata_dummy_port_info };
+       static const struct ata_port_info no_udma_info = {
+               .flags = ATA_FLAG_SLAVE_POSS,
+               .pio_mask = ATA_PIO4,
+               .port_ops = &cs5536_port_ops,
+       };
+
+
+       const struct ata_port_info *ppi[2];
        u32 cfg;
 
+       if (dmi_check_system(udma_quirk_dmi_table))
+               ppi[0] = &no_udma_info;
+       else
+               ppi[0] = &info;
+
+       ppi[1] = &ata_dummy_port_info;
+
        if (use_msr)
                printk(KERN_ERR DRV_NAME ": Using MSR regs instead of PCI\n");