linux-kernel - Re: [PATCH 1/5] iTCO_wdt: Expose watchdog properties using platform data

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Message-ID: <20150729073841.GF2284@x1>
Date:	Wed, 29 Jul 2015 08:38:41 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Aaron Sierra <asierra@...-inc.com>
Cc:	Matt Fleming <matt@...eblueprint.co.uk>,
	Wim Van Sebroeck <wim@...ana.be>,
	linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Jean Delvare <jdelvare@...e.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Matt Fleming <matt.fleming@...el.com>,
	Peter Tyser <ptyser@...-inc.com>,
	Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH 1/5] iTCO_wdt: Expose watchdog properties using platform
 data

On Tue, 28 Jul 2015, Aaron Sierra wrote:

> > > > > @@ -933,7 +956,7 @@ gpe0_done:
> > > > >  	lpc_chipset_info[priv->chipset].use_gpio = ret;
> > > > >  	lpc_ich_enable_gpio_space(dev);
> > > > >  
> > > > > -	lpc_ich_finalize_cell(dev, &lpc_ich_cells[LPC_GPIO]);
> > > > > +	lpc_ich_finalize_gpio_cell(dev);
> > > > >  	ret = mfd_add_devices(&dev->dev, PLATFORM_DEVID_AUTO,
> > > > >  			      &lpc_ich_cells[LPC_GPIO], 1, NULL, 0, NULL);
> > > > >  
> > > > > @@ -1007,7 +1030,10 @@ static int lpc_ich_init_wdt(struct pci_dev *dev)
> > > > >  		res->end = base_addr + ACPIBASE_PMC_END;
> > > > >  	}
> > > > >  
> > > > > -	lpc_ich_finalize_cell(dev, &lpc_ich_cells[LPC_WDT]);
> > > > > +	ret = lpc_ich_finalize_wdt_cell(dev);
> > > > > +	if (ret)
> > > > > +		goto wdt_done;
> > > > > +
> > > > >  	ret = mfd_add_devices(&dev->dev, PLATFORM_DEVID_AUTO,
> > > > >  			      &lpc_ich_cells[LPC_WDT], 1, NULL, 0, NULL);
> > > > 
> > > > Why do you have an mfd_add_devices() call for each device?
> > >  
> > > Good question. This call has been present since March 2012 when support
> > > was first added for iTCO_wdt in commit 887c8ec7219f ("watchdog: Convert
> > > iTCO_wdt driver to mfd model").
> > > 
> > > There's no good reason that I can see. Aaron?
> 
> I chose to call mfd_add_devices() in each device init function
> because I thought it was the easiest way to avoid registering an
> incomplete/invalid MFD cell should an error occur during init.
> 
> That way device registration wouldn't be an all-or-nothing affair.
> 
> Doesn't mfd_add_devices() bail out after the first unsuccessful
> mfd to platform device translation?

Right, as it should.

Under what circumstance would an error occur and you'd wish to carry
on registering devices?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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