linux-kernel - Re: [PATCH v6 4/4] phy: exynos5-usbdrd: Calibrate LOS levels for exynos5420/5800

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Message-ID: <CAFp+6iHMhbi4V4LAkNsgzDc192ihT2a1mZHgLbia=K2U8+x=2w@mail.gmail.com>
Date:	Wed, 10 Sep 2014 10:53:23 +0530
From:	Vivek Gautam <gautam.vivek@...sung.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Julius Werner <jwerner@...gle.com>,
	Julius Werner <jwerner@...omium.org>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Greg KH <gregkh@...uxfoundation.org>, kishon <kishon@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Jingoo Han <jg1.han@...sung.com>
Subject: Re: [PATCH v6 4/4] phy: exynos5-usbdrd: Calibrate LOS levels for exynos5420/5800

On Wed, Sep 10, 2014 at 10:23 AM, Felipe Balbi <balbi@...com> wrote:
> On Wed, Sep 10, 2014 at 09:09:57AM +0530, Vivek Gautam wrote:
>> On Wed, Sep 10, 2014 at 9:07 AM, Vivek Gautam <gautam.vivek@...sung.com> wrote:
>> > adding Julius here,
>>
>> i think i had missed adding Julius for this entire series :-(
>> I should be more careful with the CC list in future.
>> Added his chromium id, since that seems to be more active.
>>
>> >
>> >
>> > On Tue, Sep 9, 2014 at 8:12 PM, Felipe Balbi <balbi@...com> wrote:
>> >> On Tue, Sep 09, 2014 at 07:19:50AM +0530, Vivek Gautam wrote:
>> >>> Hi,
>> >>>
>> >>>
>> >>> On Mon, Sep 8, 2014 at 7:14 PM, Felipe Balbi <balbi@...com> wrote:
>> >>> > Hi,
>> >>> >
>> >>> > On Mon, Sep 08, 2014 at 09:53:09AM +0530, Vivek Gautam wrote:
>> >>> >> On Fri, Sep 5, 2014 at 11:26 PM, Felipe Balbi <balbi@...com> wrote:
>> >>> >> > On Thu, Sep 04, 2014 at 12:01:19PM +0530, Vivek Gautam wrote:
>> >>> >> >> > Don't we have phy_power_on()
>> >>> >> >> > for that ? It looks like you could just as well do this from
>> >>> >> >> > phy_power_on() ?
>> >>> >> >>
>> >>> >> >> No, unfortunately keeping these calibration settings in phy_power_on()
>> >>> >> >> doesn't help, since we need to do this after XHCI reset has happened.
>> >>> >> >
>> >>> >> > teach xHCI about PHYs ?
>> >>> >>
>> >>> >> sorry i couldn't understand you here.
>> >>> >> Aren't we trying to do the same with Heikki's patch about dwc3 :
>> >>> >> [PATCH 6/6] usb: dwc3: host: convey the PHYs to xhci
>> >>> >>
>> >>> >> and the 2nd patch in this series :
>> >>> >> [PATCH v6 2/4] usb: host: xhci-plat: Get PHYs for xhci's hcds
>> >>> >>
>> >>> >> Is there something else that is expected ?
>> >>> >
>> >>> > right, use that to call phy_init() at the right time, then you need to
>> >>> > add a new ->calibrate() method which, likely, will only be used by you
>> >>> > ;-)
>> >>>
>> >>> so you mean, the xhci should itself call phy_init() at a time suitable,
>> >>> so that ->calibrate() is not required at all ?
>> >>>
>> >>> i think you meant there - "then you __do not__ need to
>> >>
>> >> right :-)
>> >
>> > alright, i will prepare a patch for the suggested change.
>> >
>> > But AFAI remember we had discussion for this patch in earlier
>> > version, and Julius suggested to use a generic approach for such
>> > change wherein other users in future may be able to use the
>> > facility.
>
> right, and what's more generic than adding the support for PHYs straight
> into xHCI ?
>
> What I fear is that we end up opening the doors for every odd
> platform-specific operation to be added to the framework without really
> considering what needs to be done. That would defeat the idea of having
> a generic framework altogether.

Ok, i will prepare the patch series as suggested and post it
to gather opinion from you. :-)

>
> cheers
>
> --
> balbi



-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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