linux-kernel - [PATCH] pata_cs5536: add quirk for broken udma

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Date:	Thu, 15 Nov 2012 23:03:22 +0100
From:	Christian Gmeiner <christian.gmeiner@...il.com>
To:	linux-ide@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	mkp@....net, jgarzik@...ox.com
Subject: [PATCH] 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@...il.com>
---
 drivers/ata/pata_cs5536.c | 32 ++++++++++++++++++++++++++++++
+-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/pata_cs5536.c b/drivers/ata/pata_cs5536.c
index dec1b6c..0448860 100644
--- 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");


--
1.7.12.2.421.g261b511
--
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