Re: [PATCH 2.6.22-rc5 2/2] sata_promise: SATA hotplug support

[Tejun Heo <htejun@gmail.com>]

Mikael Pettersson wrote:
> This patch enables hotplugging of SATA devices in the
> sata_promise driver. It's been tested successfully on
> both first- and second-generation Promise SATA chips:
> SATA150 TX2plus, SATAII150 TX2plus, SATA300 TX2plus,
> and SATA300 TX4.
> 
> The only quirk I've seen is that hotplugging (insertion)
> on the first-generation SATA150 TX2plus requires a lengthier
> EH sequence than on the second-generation chips.
> On the second-generation chips a simple soft reset seems
> to suffice, but on the first-generation chip there's a
> "port is slow to respond" after the initial soft reset,
> after which libata issues a hard reset, and then the
> device is recognised.
> 
> The hotplug checks are high up in the interrupt handling
> path, not deep down in error_intr as in ahci/sata_sil24.
> That's because the chip doesn't signal hotplug status changes
> in the per-port status register: instead a global register
> contains hotplug control and status flags for all ports.
> I considered following the ahci/sata_sil24 structure, but
> that would have required non-trivial changes to the interrupt
> handling path, so I chose to keep the hotplug changes simple
> and unobtrusive.
> 
> Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>

Some unlikely()'s might be helpful here and there but other than that.

Acked-by: Tejun Heo <htejun@gmail.com>

-- 
tejun