linux-kernel - Re: [PATCH v6] rtc: isl12026: Add driver.

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Message-ID: <20180302234311.GE1479@piout.net>
Date:   Sat, 3 Mar 2018 00:43:11 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     David Daney <ddaney.cavm@...il.com>
Cc:     David Daney <david.daney@...ium.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-rtc@...r.kernel.org,
        devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v6] rtc: isl12026: Add driver.

On 02/03/2018 at 08:22:22 -0800, David Daney wrote:
> I am no longer able to test this patch as I lost access to the hardware.
> 

Ah, too bad. I will take your patch as-is and then add a small patch to
fixup the nvmem registration.

> If someone else wants to take charge of the patch, that would be great.
> 
> Sorry I couldn't drive this to completion,
> David Daney
> 
> On Wed, Feb 28, 2018 at 7:17 AM, Alexandre Belloni <
> alexandre.belloni@...e-electrons.com> wrote:
> 
> > Hi,
> >
> > That's mostly good
> >
> > On 22/02/2018 at 12:04:32 -0800, David Daney wrote:
> > > +     priv->rtc->ops = &isl12026_rtc_ops;
> > > +     priv->rtc->nvram_old_abi = false;
> >
> > This allocation is not necessary and I would refer not having t so when
> > the ABI goes away, it is not necessary to change this driver.
> >
> > > +     ret = rtc_register_device(priv->rtc);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     memset(&nvm_cfg, 0, sizeof(nvm_cfg));
> > > +     nvm_cfg.name = "eeprom";
> >
> > You probably need something more descriptive, usually the rtc model name
> > else, it is difficult (but not impossible) to find where this nvmem is
> > actually located when using /sys/bus/nvmem/devices
> > isl12026- would be a good choice.
> >
> > > +     nvm_cfg.read_only = false;
> > > +     nvm_cfg.root_only = true;
> >
> > any reason to have it root only?
> >
> > > +     nvm_cfg.base_dev = &client->dev;
> > > +     nvm_cfg.priv = priv;
> > > +     nvm_cfg.stride = 1;
> > > +     nvm_cfg.word_size = 1;
> > > +     nvm_cfg.size = 512;
> > > +     nvm_cfg.reg_read = isl12026_nvm_read;
> > > +     nvm_cfg.reg_write = isl12026_nvm_write;
> > > +
> > > +     return rtc_nvmem_register(priv->rtc, &nvm_cfg);
> >
> > The probe function must not fail after rtc_register_device has been
> > called so you must return 0 here.
> >
> > It is not currently possible to call rtc_nvmem_register before
> > rtc_register_device unless we move the nvmem to the parent device:
> >
> > diff --git a/drivers/rtc/nvmem.c b/drivers/rtc/nvmem.c
> > index 3a02357eb783..17ec4c8d0fad 100644
> > --- a/drivers/rtc/nvmem.c
> > +++ b/drivers/rtc/nvmem.c
> > @@ -91,7 +91,7 @@ int rtc_nvmem_register(struct rtc_device *rtc,
> >         if (!nvmem_config)
> >                 return -ENODEV;
> >
> > -       nvmem_config->dev = &rtc->dev;
> > +       nvmem_config->dev = rtc->dev.parent;
> >         nvmem_config->owner = rtc->owner;
> >         rtc->nvmem = nvmem_register(nvmem_config);
> >         if (IS_ERR_OR_NULL(rtc->nvmem))
> >
> > I'll submit this patch for this cycle before there are many users of the
> > interface (converted drivers are still exposing the old ABI).
> >
> > If you prefer, you can depend on it.
> >
> > --
> > Alexandre Belloni, Bootlin (formerly Free Electrons)
> > Embedded Linux and Kernel engineering
> > https://bootlin.com
> > --
> > To unsubscribe from this list: send the line "unsubscribe devicetree" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com