From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753646AbeBZOYe (ORCPT ); Mon, 26 Feb 2018 09:24:34 -0500 Received: from esa4.microchip.iphmx.com ([68.232.154.123]:26276 "EHLO esa4.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753325AbeBZOY1 (ORCPT ); Mon, 26 Feb 2018 09:24:27 -0500 X-IronPort-AV: E=Sophos;i="5.47,396,1515481200"; d="scan'208";a="11497802" Subject: Re: [PATCH v3 05/10] pwm: add PWM mode to pwm_config() To: Jani Nikula , Daniel Thompson CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <1519300881-8136-1-git-send-email-claudiu.beznea@microchip.com> <1519300881-8136-6-git-send-email-claudiu.beznea@microchip.com> <20180222123308.mypx2r7n6o63mj5z@oak.lan> <87po4s2hve.fsf@intel.com> From: Claudiu Beznea Message-ID: <3a70b89c-b470-3723-760c-5294d0a75230@microchip.com> Date: Mon, 26 Feb 2018 16:24:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <87po4s2hve.fsf@intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26.02.2018 11:57, Jani Nikula wrote: > On Thu, 22 Feb 2018, Daniel Thompson wrote: >> On Thu, Feb 22, 2018 at 02:01:16PM +0200, Claudiu Beznea wrote: >>> Add PWM mode to pwm_config() function. The drivers which uses pwm_config() >>> were adapted to this change. >>> >>> Signed-off-by: Claudiu Beznea >>> --- >>> arch/arm/mach-s3c24xx/mach-rx1950.c | 11 +++++++++-- >>> drivers/bus/ts-nbus.c | 2 +- >>> drivers/clk/clk-pwm.c | 3 ++- >>> drivers/gpu/drm/i915/intel_panel.c | 17 ++++++++++++++--- >>> drivers/hwmon/pwm-fan.c | 2 +- >>> drivers/input/misc/max77693-haptic.c | 2 +- >>> drivers/input/misc/max8997_haptic.c | 6 +++++- >>> drivers/leds/leds-pwm.c | 5 ++++- >>> drivers/media/rc/ir-rx51.c | 5 ++++- >>> drivers/media/rc/pwm-ir-tx.c | 5 ++++- >>> drivers/video/backlight/lm3630a_bl.c | 4 +++- >>> drivers/video/backlight/lp855x_bl.c | 4 +++- >>> drivers/video/backlight/lp8788_bl.c | 5 ++++- >>> drivers/video/backlight/pwm_bl.c | 11 +++++++++-- >>> drivers/video/fbdev/ssd1307fb.c | 3 ++- >>> include/linux/pwm.h | 6 ++++-- >>> 16 files changed, 70 insertions(+), 21 deletions(-) >>> >>> diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c >>> index 2030a6b77a09..696fa25dafd2 100644 >>> --- a/drivers/video/backlight/lm3630a_bl.c >>> +++ b/drivers/video/backlight/lm3630a_bl.c >>> @@ -165,8 +165,10 @@ static void lm3630a_pwm_ctrl(struct lm3630a_chip *pchip, int br, int br_max) >>> { >>> unsigned int period = pchip->pdata->pwm_period; >>> unsigned int duty = br * period / br_max; >>> + struct pwm_caps caps = { }; >>> >>> - pwm_config(pchip->pwmd, duty, period); >>> + pwm_get_caps(pchip->pwmd->chip, pchip->pwmd, &caps); >>> + pwm_config(pchip->pwmd, duty, period, BIT(ffs(caps.modes) - 1)); >> >> Well... I admit I've only really looked at the patches that impact >> backlight but dispersing this really odd looking bit twiddling >> throughout the kernel doesn't strike me a great API design. >> >> IMHO callers should not be required to find the first set bit in >> some specially crafted set of capability bits simply to get sane >> default behaviour. > > Agreed. IMHO the regular use case becomes rather tedious, ugly, and > error prone. Using simply PWM_MODE(NORMAL) instead of BIT(ffs(caps.modes) - 1) would be OK from your side? Or, what about using a function like pwm_mode_first() to get the first supported mode by PWM channel? Or, would you prefer to solve this inside pwm_config() function, let's say, in case an invalid mode is passed as argument, to let pwm_config() to choose the first available PWM mode for PWM channel passed as argument? Thank you, Claudiu Beznea > > BR, > Jani. > >