During S3 resume, AHCI driver sleeps 1 second to wait for the HBA reset
to finish. This is luxurious, :)
According to the AHCI 1.2 spec, We should poll the HOST_CTL register,
and return error if the host reset is not finished within 1 second.
Test results show that the HBA reset can be done quickly(in usecs).
And this patch may save nearly 1 second during resume.
Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
--
drivers/ata/ahci.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/ata/ahci.c
===================================================================
--- linux-2.6.orig/drivers/ata/ahci.c 2007-05-03 11:06:33.000000000 +0800
+++ linux-2.6/drivers/ata/ahci.c 2008-07-02 16:25:54.000000000 +0800
@@ -1073,18 +1073,29 @@
/* global controller reset */
if (!ahci_skip_host_reset) {
+ int delay = msecs_to_jiffies(1000);
+ int timeout;
+
tmp = readl(mmio + HOST_CTL);
if ((tmp & HOST_RESET) == 0) {
writel(tmp | HOST_RESET, mmio + HOST_CTL);
readl(mmio + HOST_CTL); /* flush */
}
- /* reset must complete within 1 second, or
+ /*
+ * to perform host reset, OS should set HOST_RESET
+ * and poll until this bit is read to be "0"
+ * reset must complete within 1 second, or
* the hardware should be considered fried.
*/
- ssleep(1);
+ timeout = jiffies + delay;
+ while (jiffies < timeout) {
+ tmp = readl(mmio + HOST_CTL);
+ if (!(tmp & HOST_RESET))
+ break;
+ cpu_relax();
+ }
- tmp = readl(mmio + HOST_CTL);
if (tmp & HOST_RESET) {
dev_printk(KERN_ERR, host->dev,
"controller reset failed (0x%x)\n", tmp);
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