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

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Date:	Thu, 11 Sep 2014 11:54:28 -0500
From:	Felipe Balbi <balbi@...com>
To:	Kishon Vijay Abraham I <kishon@...com>
CC:	Vivek Gautam <gautam.vivek@...sung.com>,
	Felipe Balbi <balbi@...com>,
	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>,
	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

Hi,

On Thu, Sep 11, 2014 at 09:10:21PM +0530, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Wednesday 10 September 2014 01:26 PM, Vivek Gautam wrote:
> > On Wed, Sep 10, 2014 at 10:53 AM, Vivek Gautam <gautam.vivek@...sung.com> wrote:
> >> 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 ?
> > 
> > but wait, dwc3 does a phy_init() already, then how xhci will be able to
> > do that again. We can't do phy_init() multiple times right ?
> 
> right. I think we should split and do phy ops separately for dwc3 host
> and gadget?

no, don't do that. We need a better way of handling this. As of now we
don't support dual-role, so we can just reinitialize the PHY once we
reach xhci.

Once we start supporting dual-role, we will need more inteligence in the
algorithm.

-- 
balbi

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