Zhang Rui wrote:
> On Fri, 2008-07-04 at 10:48 +0800, Tejun Heo wrote:
>> Hello, Zhang.
>>
>> Zhang Rui wrote:
>>> 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();
>>> + }
>> Looks good in principle. Just two things...
>>
>> 1. Please don't busy-loop. e.g. No one would notice 10ms delay
>> between
>> polls.
>>
>> 2. Please use ata_wait_register().
>>
> Thanks for review, refreshed patch attached. :)
>
> From: Zhang Rui <rui.zhang@xxxxxxxxx>
>
> During resume, sleep 1 second to wait for the HBA reset
> to finish is a waste of time.
>
> 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 | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/drivers/ata/ahci.c
> ===================================================================
> --- linux-2.6.orig/drivers/ata/ahci.c 2008-07-04 09:49:05.000000000 +0800
> +++ linux-2.6/drivers/ata/ahci.c 2008-07-04 11:31:30.000000000 +0800
> @@ -1079,12 +1079,15 @@
> 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);
> + tmp = ata_wait_register(mmio + HOST_CTL, HOST_RESET,
> + HOST_RESET, 10, 1000);
>
> - tmp = readl(mmio + HOST_CTL);
> if (tmp & HOST_RESET) {
> dev_printk(KERN_ERR, host->dev,
> "controller reset failed (0x%x)\n", tmp);
>
applied
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