Some devices raise irq early before clearing the BSY.
This patch waits up to 10 microseconds to workaround the early irq problem.
Signed-off-by: Albert Lee <albertcc@xxxxxxxxxx>
---
In additional to the pata_via SET FEATURES XFER problem reported by Matthieu,
we also see the early irq problem with ICH4 + AOpen CD-936E on READ under PIO mode 4.
The following is a port of the pata_via_fix to the libata core.
Patch against 2.6.19-rc6. For your review, thanks.
--- linux-2.6.19-rc6/include/linux/libata.h 2006-11-28 11:14:52.000000000 +0800
+++ linux-2.6.19-rc6-early_irq/include/linux/libata.h 2006-11-28 13:31:07.565194648 +0800
@@ -1039,6 +1039,30 @@ static inline void ata_pause(struct ata_
ndelay(400);
}
+/**
+ * ata_busy_wait_alt - Wait for a port alt status register
+ * @ap: Port to wait for.
+ *
+ * Waits up to max microseconds for the selected bits in the port's
+ * alt status register to be cleared.
+ * Returns final value of alt status register.
+ *
+ * LOCKING:
+ * Inherited from caller.
+ */
+static inline u8 ata_busy_wait_alt(struct ata_port *ap, unsigned int bits,
+ unsigned int max)
+{
+ u8 status = ata_altstatus(ap);
+
+ while ((status & bits) && (max > 0)) {
+ udelay(1);
+ status = ata_altstatus(ap);
+ max--;
+ };
+
+ return status;
+}
/**
* ata_busy_wait - Wait for a port status register
--- linux-2.6.19-rc6/drivers/ata/libata-core.c 2006-11-28 11:14:38.000000000 +0800
+++ linux-2.6.19-rc6-early_irq/drivers/ata/libata-core.c 2006-11-28 13:31:31.275590120 +0800
@@ -4828,8 +4828,10 @@ inline unsigned int ata_host_intr (struc
goto idle_irq;
}
- /* check altstatus */
- status = ata_altstatus(ap);
+ /* check altstatus.
+ * Waits up to 10 microseconds for early irq.
+ */
+ status = ata_busy_wait_alt(ap, ATA_BUSY, 10);
if (status & ATA_BUSY)
goto idle_irq;
-
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