Hi all.
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. I am
looking for a way now to get
this quirk upstream. On older versions with an embedded BIOS and 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 so a good idea.
I came up with this patch. I am not sure if it would be better to
patch libata-core.c
Thanks,
---
Christian Gmeiner, MSc
--- linux-3.2.24___OK/drivers/ata/pata_cs5536.c 2012-07-25
05:11:50.000000000 +0200
+++ linux-3.2.24/drivers/ata/pata_cs5536.c 2012-07-26 15:38:27.674909884 +0200
@@ -37,6 +37,7 @@
#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>
@@ -95,6 +96,21 @@
PCI_IDE_CFG, PCI_IDE_DTC, PCI_IDE_CAST, PCI_IDE_ETC,
};
+/* 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 inline int cs5536_read(struct pci_dev *pdev, int reg, u32 *val)
{
if (unlikely(use_msr)) {
@@ -257,9 +273,22 @@
.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");
--
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