Subject: [PATCH v7 1/7] phy: add a driver for the Berlin SATA PHY

From: [email-masked] (Sebastian Hesselbarth)
Date: Mon, 30 Jun 2014 16:40:49 +0200

On 06/30/2014 11:59 AM, Antoine T?nart wrote:
> On Wed, Jun 25, 2014 at 11:03:25PM +0400, Sergei Shtylyov wrote:
>> On 06/23/2014 05:39 PM, Antoine T?nart wrote:
>>> +	/* set the controller speed */
>>> +	writel(0x31, ctrl_reg + PORT_SCR_CTL);
>>
>>     Value undocumented? Or is this the SATA SControl register by chance?
>
> Some magic is still there...

Antoine,

I guess Sergei was referring to AHCI spec here. PORT_SCR bits are
documented in AHCI spec as:

7:4 = 0x3 Limit speed negotiation to a rate not greater than Gen3
           communication rate.

3:0 = 0x1 Perform interface communication sequence [...]. This is
           functionally equivalent to a hard reset [...].

So, the question is: Should we really need to reset controller in the
PHY driver or is it already done in AHCI common code? At least we
should change the comment to something like
/* set Gen3 controller speed and perform hard reset */

Sebastian