Re: [PATCH 10/15] libata: add dev->sata_spd_limit and helpers

[Tejun Heo <htejun@gmail.com>]

Jeff Garzik wrote:
> Tejun Heo wrote:
>> dev->sata_spd_limit contrains SATA PHY speed of the device and is
>> initialized to the configured value on probing.
>>
>> Currently, This is only valid for dev[0] but still put into ata_device
>> instead of ata_port.  This is because 1. it's device constraints
>> (ie. when hotpluggin, it should be cleared with other device info)
>> 2. for port multiplier, link actually belongs to each device.
>>
>> Three helper functions - ata_down_sata_spd_limit(),
>> ata_set_sata_spd_needed() and ata_set_sata_spd() - are implemented.
>> They will be used by ata_bus_probe() rewrite and later by EH.
>>
>> Signed-off-by: Tejun Heo <htejun@gmail.com>
> 
> NAK, I definitely don't want to closely associate phy and device 
> parameters, because they are fundamentally two different things.
> 
> We program and address PHYs, so perhaps a sata_phy struct is needed.
> 
> Port multipliers also get interesting because we need to use ATA-ish 
> commands to talk to the PM phys.  Perhaps a struct ata_port_mult inside 
> ata_device is warranted, where one stores an array of sata_phy structs, 
> and other PM-specific details.
> 

Hmmm... Yeah I also thought about extracting out PHY related information 
out such that PATAs share them, SATA and PM have their own maybe marked 
to indicate how they are connected. But that looked like going too far 
especially because we don't have PM support yet. So, sticking it into 
dev was sorta middle-ground.

How about putting it into ata_port around ap->cbl? This fits the current 
model better and should work the same.

-- 
tejun