linux-kernel - Re: [PATCH v2 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC

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Date:   Mon, 20 Apr 2020 13:41:28 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Boris Brezillon <boris.brezillon@...labora.com>
Cc:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:MEMORY TECHNOLOGY..." <linux-mtd@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh R <vigneshr@...com>, Arnd Bergmann <arnd@...db.de>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Anders Roxell <anders.roxell@...aro.org>,
        masonccyang@...c.com.tw, piotrs@...ence.com,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        "hauke.mehrtens" <hauke.mehrtens@...el.com>, qi-ming.wu@...el.com,
        cheol.yong.kim@...el.com
Subject: Re: [PATCH v2 2/2] mtd: rawnand: Add NAND controller support on
 Intel LGM SoC

On Mon, Apr 20, 2020 at 12:28:59PM +0200, Boris Brezillon wrote:
> On Mon, 20 Apr 2020 13:14:42 +0300
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> > On Mon, Apr 20, 2020 at 12:53 PM Boris Brezillon
> > <boris.brezillon@...labora.com> wrote:
> > > On Mon, 20 Apr 2020 12:44:51 +0300
> > > Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> > > > On Mon, Apr 20, 2020 at 12:21 PM Boris Brezillon
> > > > <boris.brezillon@...labora.com> wrote:  
> > > > > On Mon, 20 Apr 2020 01:20:40 +0300
> > > > > Andy Shevchenko <andriy.shevchenko@...el.com> wrote:  
> > > > > > On Sat, Apr 18, 2020 at 10:55:33AM +0200, Boris Brezillon wrote:  
> > > > > > > On Fri, 17 Apr 2020 16:21:47 +0800
> > > > > > > "Ramuthevar,Vadivel MuruganX"
> > > > > > > <vadivel.muruganx.ramuthevar@...ux.intel.com> wrote:

...

> > > > > > > > +static const struct of_device_id lgm_nand_match[] = {
> > > > > > > > + { .compatible = "intel,lgm-nand", },
> > > > > > > > + {}
> > > > > > > > +};
> > > > > > > > +MODULE_DEVICE_TABLE(of, lgm_nand_match);  
> > > > > > >
> > > > > > > You probably have a missing "depends on OF" in your Kconfig.  
> > > > > >
> > > > > > Since it's using device property API, dependency is not needed.
> > > > > >  
> > > > >
> > > > > There's no compile-time dependency, but this driver will be pretty
> > > > > useless if all its users have the NAND controller node defined in their
> > > > > DT and CONFIG_OF is not enabled.  
> > > >
> > > > No, it's not.
> > > > See [1] for the details how ACPI may utilize this table.
> > > >
> > > > [1]: https://www.kernel.org/doc/html/latest/firmware-guide/acpi/enumeration.html#device-tree-namespace-link-device-id  
> > >
> > > Except the NAND framework does use the OF lib when parsing common DT
> > > properties (like nand-ecc-mode, etc), so it does depend on OF if you
> > > want those props to be parsed, which, according to the DT binding patch,
> > > is the case.  
> > 
> > I see, so, NAND framework can be transformed at some point. In any
> > case, from driver perspective it's OF independent.
> > 
> 
> Well, it uses it only if the driver passes an OF node which this driver
> does (see the nand_set_flash_node() call), so no, it's really a driver
> dependency.

Look like still it's framework dependency which driver has to rely on.
Means more work would be needed in case NAND to convert to fwnode API.

-- 
With Best Regards,
Andy Shevchenko