linux-kernel - Re: [PATCH v12 1/4] PHY: Add function set

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Message-ID: <20140227205039.GE5375@saruman.home>
Date:	Thu, 27 Feb 2014 14:50:39 -0600
From:	Felipe Balbi <balbi@...com>
To:	Loc Ho <lho@....com>
CC:	<balbi@...com>, Kishon Vijay Abraham I <kishon@...com>,
	Tejun Heo <tj@...nel.org>, Olof Johansson <olof@...om.net>,
	Arnd Bergmann <arnd@...db.de>, <linux-kernel@...r.kernel.org>,
	Linux SCSI List <linux-scsi@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Don Dutile <ddutile@...hat.com>, Jon Masters <jcm@...hat.com>,
	"patches@....com" <patches@....com>
Subject: Re: [PATCH v12 1/4] PHY: Add function set_speed to generic PHY
 framework

Hi,

On Thu, Feb 27, 2014 at 11:57:44AM -0800, Loc Ho wrote:
> > On Thu, Feb 27, 2014 at 11:14:05AM -0700, Loc Ho wrote:
> >> This patch adds function set_speed to the generic PHY framework operation
> >> structure. This function can be called to instruct the PHY underlying layer
> >> at specified lane to configure for specified speed in hertz.
> >
> > why ? looks like clk_set_rate() is your friend here. Can you be more
> > descriptive of the use case ? When will this be used ?
> >
> 
> The phy_set_speed is used to configure the operation speed of the PHY
> at run-time. The clock interface in general is used to configure the
> clock input to the IP. I don't believe they are the same thing. Maybe
> it will be clear in my response to your second email

The problem with this is that you end up adding SATA-specific details to
something which is supposed to be generic. After negoatiation, don't you
get any interrupt from your PHY indicating that link speed negotiation
is done ? Or is that IRQ only on AHCI IP ?


cheers

-- 
balbi

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