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[82.203.185.45]) by smtp.gmail.com with ESMTPSA id p20-v6sm526952lji.37.2018.07.04.02.52.59 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 04 Jul 2018 02:53:01 -0700 (PDT) Date: Wed, 4 Jul 2018 12:52:57 +0300 From: Matti Vaittinen To: Enric Balletbo Serra Cc: Michael Turquette , Rob Herring , Mark Rutland , Lee Jones , Liam Girdwood , Mark Brown , Matti Vaittinen , Arnd Bergmann , Dmitry Torokhov , Sebastian Reichel , chenjh@rock-chips.com, Andrey Smirnov , Linus Walleij , Kate Stewart , Heiko =?iso-8859-1?Q?St=FCbner?= , Greg Kroah-Hartman , sboyd@kernel.org, linux-clk@vger.kernel.org, "devicetree@vger.kernel.org" , linux-kernel , linux-input@vger.kernel.org, mikko.mutanen@fi.rohmeurope.com, heikki.haikola@fi.rohmeurope.com Subject: Re: [PATCH v8 1/2] mfd: bd71837: mfd driver for ROHM BD71837 PMIC Message-ID: <20180704095257.GJ2118@localhost.localdomain> References: <18a04e42debb2a23aec855cac3bcf3d6ab6c55fd.1530259815.git.matti.vaittinen@fi.rohmeurope.com> <20180704083911.GH2118@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180704083911.GH2118@localhost.localdomain> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 04, 2018 at 11:39:11AM +0300, Matti Vaittinen wrote: > On Tue, Jul 03, 2018 at 11:26:00AM +0200, Enric Balletbo Serra wrote: > > Missatge de Matti Vaittinen del > > dia dv., 29 de juny 2018 a les 11:47: > > > > Now that you use devm calls and you don't need to unwind things I > > think is better to use plain returns. So, > > > > return -ENOMEM; > > I have never really understood why use of gotos in error handling is > discouraged. Personally I would always choose single point of exit from > a function when it is simple enough to achieve (like in this case). I've > written and fixed way too many functions which leak resources or > accidentally keep a lock when exiting from error branches. But I know > many colleagues like you who prefer not to have gotos but in place returns > instead. So I guess I'll leave the final call on this to the one who is > maintainer for this code. And it is true there is no things to unwind > now - which does not mean that next updater won't add such. But as I > said, I know plenty of people share your view - and even though I rather > maintain code with only one exit the final call is on subsystem maintainer > here. Actually, If it was completely my call the probe would look something like this: +static int bd71837_i2c_probe(struct i2c_client *i2c, + const struct i2c_device_id *id) +{ + struct bd71837 *bd71837; + struct bd71837_board *board_info; + int gpio_intr = 0; + + const char *errstr = "No IRQ configured"; + int ret = -EINVAL; + + bd71837 = devm_kzalloc(&i2c->dev, sizeof(struct bd71837), GFP_KERNEL); + + if (bd71837 == NULL) + return -ENOMEM; + + board_info = dev_get_platdata(&i2c->dev); + + if (!board_info) + gpio_intr = i2c->irq; + else + gpio_intr = board_info->gpio_intr; + + if (!gpio_intr) + goto err_out; + + i2c_set_clientdata(i2c, bd71837); + bd71837->dev = &i2c->dev; + bd71837->i2c_client = i2c; + bd71837->chip_irq = gpio_intr; + + errstr = "regmap initialization failed"; + + bd71837->regmap = devm_regmap_init_i2c(i2c, &bd71837_regmap_config); + ret = PTR_ERR(bd71837->regmap); + if (IS_ERR(bd71837->regmap)) + goto err_out; + + errstr = "Read BD71837_REG_DEVICE failed"; + ret = bd71837_reg_read(bd71837, BD71837_REG_REV); + if (ret < 0) + goto err_out; + + errstr = "Failed to add irq_chip"; + ret = devm_regmap_add_irq_chip(&i2c->dev, bd71837->regmap, + bd71837->chip_irq, IRQF_ONESHOT, 0, + &bd71837_irq_chip, &bd71837->irq_data); + if (ret < 0) + goto err_out; + + errstr = "Failed to configure button short press timeout"; + ret = regmap_update_bits(bd71837->regmap, + BD71837_REG_PWRONCONFIG0, + BD718XX_PWRBTN_PRESS_DURATION_MASK, + BD718XX_PWRBTN_SHORT_PRESS_10MS); + if (ret < 0) + goto err_out; + + /* According to BD71847 datasheet the HW default for long press + * detection is 10ms. So lets change it to 10 sec so we can actually + * get the short push and allow gracefull shut down + */ + ret = regmap_update_bits(bd71837->regmap, + BD71837_REG_PWRONCONFIG1, + BD718XX_PWRBTN_PRESS_DURATION_MASK, + BD718XX_PWRBTN_LONG_PRESS_10S); + + errstr = "Failed to configure button long press timeout"; + if (ret < 0) + goto err_out; + + btns[0].irq = regmap_irq_get_virq(bd71837->irq_data, + BD71837_INT_PWRBTN_S); + + errstr = "Failed to get the IRQ"; + ret = btns[0].irq; + if (btns[0].irq < 0) + goto err_out; + + errstr = "Failed to create subdevices"; + ret = devm_mfd_add_devices(bd71837->dev, PLATFORM_DEVID_AUTO, + bd71837_mfd_cells, + ARRAY_SIZE(bd71837_mfd_cells), NULL, 0, + regmap_irq_get_domain(bd71837->irq_data)); + if (ret) { +err_out: + if (errstr) + dev_err(&i2c->dev, "%s (%d)\n", errstr, ret); + } + + return ret; +} What do you think of this? To my eye it is nice. It keeps single point of exit and introduces only simple if-statements without the need of curly brackets. And finally the error prints string works as a comment too. I've seen bunch of constructs like this on the networking side but I have no idea if this is frowned on this subsystem =) Oh, and probe abowe is just to illustrate the idea, I did not even try compiling it yet. Best Regards Matti Vaittinen