linux-kernel - RE: [PATCH v2 1/5] phy: Add new Exynos USB PHY driver

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Date:	Tue, 29 Oct 2013 11:16:07 +0100
From:	Kamil Debski <k.debski@...sung.com>
To:	'Tomasz Figa' <tomasz.figa@...il.com>
Cc:	'Kishon Vijay Abraham I' <kishon@...com>,
	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
	linux-arm@...r.kernel.org, kyungmin.park@...sung.com,
	Tomasz Figa <t.figa@...sung.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	gautam.vivek@...sung.com, mat.krawczuk@...il.com
Subject: RE: [PATCH v2 1/5] phy: Add new Exynos USB PHY driver

Hi,

> From: Tomasz Figa [mailto:tomasz.figa@...il.com]
> Sent: Monday, October 28, 2013 9:00 PM
> 
> Hi Kamil,
> 
> On Monday 28 of October 2013 14:52:19 Kamil Debski wrote:
> > Hi Kishon,
> >
> > Thank you for your review! I will answer your comments below.
> [snip]
> > > > +
> > > > +	switch (drv->cfg->cpu) {
> > > > +	case TYPE_EXYNOS4210:
> > >
> > > > +	case TYPE_EXYNOS4212:
> > > Lets not add such cpu checks inside driver.
> >
> > Some SoC have a special register, which switches the OTG lines
> between
> > device and host modes. I understand that it might not be the
> prettiest
> > code. I see this as a good compromise between having a single huge
> > driver for all Exynos SoCs and having a multiple drivers for each SoC
> > version. PHY IPs in these chips very are similar but have to be
> > handled differently. Any other ideas to solve this issue?
> 
> Maybe adding a flag in drv->cfg called, for example, .has_mode_switch
> could solve this problem without having to check the SoC type
> explicitly?

Sounds like a good idea.
 
> [snip]
> > > > +#ifdef CONFIG_PHY_EXYNOS4210_USB
> > >
> > > Do we really need this?
> >
> > No we don't. The driver can always support all Exynos SoC versions.
> > These config options were added for flexibility.
> >
> > > > +extern const struct uphy_config exynos4210_uphy_config; #endif
> > > > +
> > > > +#ifdef CONFIG_PHY_EXYNOS4212_USB
> > >
> > > Same here.
> > >
> > > > +extern const struct uphy_config exynos4212_uphy_config; #endif
> > > > +
> > > > +static const struct of_device_id exynos_uphy_of_match[] = {
> > > > +#ifdef CONFIG_PHY_EXYNOS4210_USB
> > >
> > > #if not needed here.
> >
> > If the #ifdef CONFIG_PHY_EXYNOS4210_USB is removed then yes.
> Otherwise
> > it is necessary - exynos4210_uphy_config may be undefined.
> 
> I believe this and other ifdefs below are needed, otherwise, with
> support for one of the SoCs disabled, the driver could still bind to
> its compatible value.
> 

Best wishes,
-- 
Kamil Debski
Samsung R&D Institute Poland


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