Re: [PATCH 1/1] AHCI: disabled FBS prior to issuing software reset

[xiangliang yu]

hi, Tejun
i had tested the patch with Marvell 88se9235. And driver can find disk
if FBS disabled, or can't find disk.
Please see chapter 9.3.9 and 9.3.8 of AHCI spec. Thanks.


2013/9/28 Tejun Heo <tj@xxxxxxxxxx>:
> Hello,
>
> On Sat, Sep 28, 2013 at 07:13:36PM +0800, Xiangliang Yu wrote:
>> If device is attached to port multiplier, the detection process
>> look like this:
>>       ahci_hardreset(link, class, deadline)
>>       if (class == ATA_DEV_PMP) {
>>               sata_pmp_attach(dev)    /* will enable FBS */
>>               sata_pmp_init_links(ap, nr_ports);
>>               ata_for_each_link(link, ap, EDGE) {
>>                       sata_std_hardreset(link, class, deadline);
>>                       if (link_is_online)
>>                               ahci_softreset(link, class, deadline);
>>               }
>>       }
>> But, according to chapter 9.3.9 in AHCI spec: Prior to issuing software reset,
>> software shall clear PxCMD.ST to '0' and then clear PxFBS.EN to '0'.
>
> How was this tested?  Do you observe any behavior difference?  At this
> point, we are not using SRST on PMP ports anyway, so I can't see how
> this would make any difference.
>
> Thanks.
>
> --
> tejun
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