From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH v3 2/3] i2c: iproc: Add Broadcom iProc I2C Driver Date: Wed, 14 Jan 2015 08:51:37 +0100 Message-ID: <20150114075137.GL22880@pengutronix.de> References: <1418183832-24793-1-git-send-email-rjui@broadcom.com> <1418183832-24793-3-git-send-email-rjui@broadcom.com> <20150113225012.GK22880@pengutronix.de> <54B5D0F9.8030902@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <54B5D0F9.8030902@broadcom.com> Sender: linux-kernel-owner@vger.kernel.org To: Ray Jui Cc: Wolfram Sang , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Grant Likely , Christian Daudt , Matt Porter , Florian Fainelli , Russell King , Scott Branden , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, devicetree@vger.kernel.org List-Id: devicetree@vger.kernel.org Hello, On Tue, Jan 13, 2015 at 06:14:17PM -0800, Ray Jui wrote: > >> + irq =3D platform_get_irq(pdev, 0); > >> + if (irq < 0) { > > irq =3D=3D 0 should be handled as error, too. > >=20 > Ah. I thought zero is a valid global interrupt number, and I see othe= r > drivers checking against < 0 as well. Is my understanding incorrect? These are wrong, too. 0 should never be a valid interrupt number. There are some exceptions but mostly for historic reasons. The right handling is used for example in drivers/i2c/busses/i2c-efm32.c. > >> + dev_err(dev->device, "no irq resource\n"); > >> + return irq; > >> + } > [...] > >> +static int bcm_iproc_i2c_remove(struct platform_device *pdev) > >> +{ > >> + struct bcm_iproc_i2c_dev *dev =3D platform_get_drvdata(pdev); > >> + > >> + i2c_del_adapter(&dev->adapter); > >> + bcm_iproc_i2c_disable(dev); > > I think you have a problem here if bcm_iproc_i2c_remove is called w= hile > > an irq is still being serviced. I'm not sure how to prevent this > > properly for a shared interrupt. > >=20 > Can I grab i2c_lock_adapter to ensure the bus is locked (so there's n= o > outstanding transactions or IRQs by the time we remove the adapter)? = But > I see no I2C bus driver does this in their remove function... The problem I pointed out is the reason for some driver authors not to use devm_request_irq. If you use plain request_irq and the matching free_irq in the .remove callback you can be sure that the irq isn't running any more as soon as free_irq returns. BTW, if you use vim, you can add set cinoptions=3D(,: if has("autocmd") filetype plugin indent on endif to your .vimrc. Then while typing vim does the indention right and consistent, and with the =3D command you can reindent. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= |