From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753311AbbEGHTa (ORCPT ); Thu, 7 May 2015 03:19:30 -0400 Received: from mail-qk0-f170.google.com ([209.85.220.170]:34344 "EHLO mail-qk0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752681AbbEGHT1 (ORCPT ); Thu, 7 May 2015 03:19:27 -0400 MIME-Version: 1.0 In-Reply-To: <20150506121455.GB9421@ulmo> References: <1430316005-16480-7-git-send-email-shobhit.kumar@intel.com> <1430818716-27287-1-git-send-email-shobhit.kumar@intel.com> <20150506121455.GB9421@ulmo> Date: Thu, 7 May 2015 12:49:26 +0530 Message-ID: Subject: Re: [Intel-gfx] [PATCH 6/8] pwm: crc: Add Crystalcove (CRC) PWM driver From: Shobhit Kumar To: Thierry Reding Cc: Shobhit Kumar , linux-pwm , Jani Nikula , Samuel Ortiz , Alexandre Courbot , David Airlie , Povilas Staniulis , intel-gfx , linux-kernel , dri-devel , linux-gpio , Chih-Wei Huang , Daniel Vetter , Lee Jones , Linus Walleij Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 6, 2015 at 5:44 PM, Thierry Reding wrote: > On Tue, May 05, 2015 at 03:08:36PM +0530, Shobhit Kumar wrote: >> The Crystalcove PMIC controls PWM signals and this driver exports that > > You say signal_s_ here, but you only expose a single PWM device. Does > the PMIC really control more than one? If it isn't, this should probably > become: "controls a PWM output and this driver...". Actually it does support 3 of them but on the platform only one is being used and I exported only that as of now. Probably I should expand a little in the commit message indicating this. will re-post after fixing based on your other comments. Regards Shobhit > >> capability as a PWM chip driver. This is platform device implementtaion > > "implementation" > >> of the drivers/mfd cell device for CRC PMIC > > Sentences should end with a full stop. > >> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig >> index b1541f4..954da3e 100644 >> --- a/drivers/pwm/Kconfig >> +++ b/drivers/pwm/Kconfig >> @@ -183,6 +183,13 @@ config PWM_LPC32XX >> To compile this driver as a module, choose M here: the module >> will be called pwm-lpc32xx. >> >> +config PWM_CRC >> + bool "Intel Crystalcove (CRC) PWM support" >> + depends on X86 && INTEL_SOC_PMIC >> + help >> + Generic PWM framework driver for Crystalcove (CRC) PMIC based PWM >> + control. >> + > > This is badly sorted. Please keep the list sorted alphabetically. > >> config PWM_LPSS >> tristate "Intel LPSS PWM support" >> depends on X86 >> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile >> index ec50eb5..3d38fed 100644 >> --- a/drivers/pwm/Makefile >> +++ b/drivers/pwm/Makefile >> @@ -35,3 +35,4 @@ obj-$(CONFIG_PWM_TIPWMSS) += pwm-tipwmss.o >> obj-$(CONFIG_PWM_TWL) += pwm-twl.o >> obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o >> obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o >> +obj-$(CONFIG_PWM_CRC) += pwm-crc.o > > This too. > >> diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c >> new file mode 100644 >> index 0000000..987f3b4 >> --- /dev/null >> +++ b/drivers/pwm/pwm-crc.c >> @@ -0,0 +1,171 @@ >> +/* >> + * pwm-crc.c - Intel Crystal Cove PWM Driver > > I think you can safely remove this line. You already know what file it > is when you open it in your editor, and the description is in the > MODULE_DESCRIPTION string already. > >> + * >> + * Copyright (C) 2015 Intel Corporation. All rights reserved. >> + * >> + * This program is free software; you can redistribute it and/or >> + * modify it under the terms of the GNU General Public License version >> + * 2 as published by the Free Software Foundation. >> + * >> + * This program is distributed in the hope that it will be useful, >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >> + * GNU General Public License for more details. >> + * >> + * Author: Shobhit Kumar >> + */ >> + >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +#define PWM0_CLK_DIV 0x4B >> +#define PWM_OUTPUT_ENABLE (1<<7) > > Should have spaces around <<. > >> +#define PWM_DIV_CLK_0 0x00 /* DIVIDECLK = BASECLK */ >> +#define PWM_DIV_CLK_100 0x63 /* DIVIDECLK = BASECLK/100 */ >> +#define PWM_DIV_CLK_128 0x7F /* DIVIDECLK = BASECLK/128 */ >> + >> +#define PWM0_DUTY_CYCLE 0x4E >> +#define BACKLIGHT_EN 0x51 >> + >> +#define PWM_MAX_LEVEL 0xFF >> + >> +#define PWM_BASE_CLK 6000 /* 6 MHz */ > > This number is actually 6 KHz. I think it'd be better if you stuck with > one unit here. Or perhaps there's some other reason why you can't use > 6000000 here instead? > >> +#define PWM_MAX_PERIOD_NS 21333 /* 46.875KHz */ >> + >> +/** >> + * struct crystalcove_pwm - Crystal Cove PWM controller >> + * @chip: the abstract pwm_chip structure. >> + * @regmap: the regmap from the parent device. >> + */ >> +struct crystalcove_pwm { >> + struct pwm_chip chip; >> + struct platform_device *pdev; > > I think I had at some point requested that you get rid of this and use > the chip.dev member instead. There's no kerneldoc for it and it isn't > (well, almost, see below) used anywhere else, so perhaps you forgot to > remove it here? > >> + struct regmap *regmap; >> +}; >> + >> +static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc) >> +{ >> + return container_of(pc, struct crystalcove_pwm, chip); >> +} >> + >> +static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm) >> +{ >> + struct crystalcove_pwm *crc_pwm = to_crc_pwm(c); >> + >> + regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1); >> + >> + return 0; >> +} >> + >> +static void crc_pwm_disable(struct pwm_chip *c, struct pwm_device *pwm) >> +{ >> + struct crystalcove_pwm *crc_pwm = to_crc_pwm(c); >> + >> + regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0); >> +} >> + >> +static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm, >> + int duty_ns, int period_ns) > > Please align arguments on subsequent lines with the first argument of > the first line. > >> +{ >> + struct crystalcove_pwm *crc_pwm = to_crc_pwm(c); >> + struct device *dev = &crc_pwm->pdev->dev; > > Did you test reconfiguring the PWM? I don't see crc_pwm->pdev getting > initialized anywhere, so this should crash trying to dereference a NULL > pointer. > > Of course if you get rid of the pdev field as I suggested you can simply > get the struct device * from c->dev. > >> + int level, percent; >> + >> + if (period_ns > PWM_MAX_PERIOD_NS) { >> + dev_err(dev, "un-supported period_ns\n"); >> + return -1; > > You should return -EINVAL here. Besides being a literal and therefore a > bad idea, -1 == -EPERM and doesn't match the error condition. > >> + } >> + >> + if (pwm->period != period_ns) { >> + int clk_div; >> + >> + /* changing the clk divisor, need to disable fisrt */ >> + crc_pwm_disable(c, pwm); >> + clk_div = PWM_BASE_CLK * period_ns / 1000000; > > Similar to the above, this is confusing because you're mixing up > different scales here. period_ns is in nanoseconds, so it'd be natural > to divide by 1000000000 (though you should really be using NSEC_PER_SEC > instead). If you counterweight that by expressing PWM_BASE_CLK in Hz > (6000000) you get much nicer symmetry and make the code a lot easier to > understand. > >> + >> + regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, >> + clk_div | PWM_OUTPUT_ENABLE); >> + >> + /* enable back */ >> + crc_pwm_enable(c, pwm); >> + } >> + >> + if (duty_ns > period_ns) { >> + dev_err(dev, "duty cycle cannot be greater than cycle period\n"); >> + return -1; >> + } > > The PWM core already performs this check, so you'll never get here in > case this condition is true. > >> + >> + /* change the pwm duty cycle */ >> + percent = duty_ns * 100 / period_ns; >> + level = percent * PWM_MAX_LEVEL / 100; > > Why do you need to apply the rule of three twice here? Doesn't > > level = duty_ns * PWM_MAX_LEVEL / period_ns; > > give you what you want? > >> + regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level); >> + >> + return 0; >> +} >> + >> +static const struct pwm_ops crc_pwm_ops = { >> + .config = crc_pwm_config, >> + .enable = crc_pwm_enable, >> + .disable = crc_pwm_disable, >> + .owner = THIS_MODULE, >> +}; >> + >> +static int crystalcove_pwm_probe(struct platform_device *pdev) >> +{ >> + struct crystalcove_pwm *pwm; >> + int retval; >> + struct device *dev = pdev->dev.parent; >> + struct intel_soc_pmic *pmic = dev_get_drvdata(dev); >> + >> + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); >> + if (!pwm) >> + return -ENOMEM; >> + >> + pwm->chip.dev = &pdev->dev; >> + pwm->chip.ops = &crc_pwm_ops; >> + pwm->chip.base = -1; >> + pwm->chip.npwm = 1; >> + >> + /* get the PMIC regmap */ >> + pwm->regmap = pmic->regmap; >> + >> + retval = pwmchip_add(&pwm->chip); >> + if (retval < 0) >> + return retval; >> + >> + dev_dbg(&pdev->dev, "crc-pwm probe successful\n"); > > Do you really want this? The driver core will complain in any of the > above failures, so what use is there to be chatty when probing > succeeds? > >> +static struct platform_driver crystalcove_pwm_driver = { >> + .probe = crystalcove_pwm_probe, >> + .remove = crystalcove_pwm_remove, >> + .driver = { >> + .name = "crystal_cove_pwm", > > I'd prefer this to be "crystal-cove-pwm" for consistency with other > drivers, but since the MFD part already uses underscores in names it'd > introduce an inconsistency there. So I'm fine with this one as-is. > > Thierry > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx >