From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Zapolskiy Date: Mon, 12 Oct 2015 15:32:18 +0000 Subject: Re: [PATCH v2] backlight: pwm: reject legacy pwm request for device defined in dt Message-Id: <561BD282.70305@mentor.com> List-Id: References: <1444652943-19712-1-git-send-email-vladimir_zapolskiy@mentor.com> <561BB2BC.9090907@atmel.com> <20151012153029.62f948d2@bbrezillon> <561BBB9F.6060808@mentor.com> <20151012160608.41f04553@bbrezillon> <561BC177.2050000@mentor.com> <20151012171931.3fb922d2@bbrezillon> In-Reply-To: <20151012171931.3fb922d2@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Boris Brezillon , Robert Jarzmik Cc: Nicolas Ferre , Thierry Reding , Lee Jones , Jingoo Han , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org On 12.10.2015 18:19, Boris Brezillon wrote: > On Mon, 12 Oct 2015 17:19:35 +0300 > Vladimir Zapolskiy wrote: >> >>> Thierry's patch makes sure that EPROBE_DEFER is not returned when the >>> PWM device definition is not found using in the PWM lookup tables or >>> the DT definition, >> >> This is okay, but I'm interested in proper handling of cases other than >> EPROBE_DEFER. EPROBE_DEFER and the related issues are on your balance >> and I'm attempting to avoid interfering with it here :) > > I keep thinking we should fix all platforms using the ->pwm_id pdata > field to attach a PWM device to a PWM backlight instead of trying to > guess when falling back to the legacy API is acceptable... > >> >>> and in this case the pwm_bl code will fallback to >>> the legacy PWM API, which AFAICT is what you're trying to solve. >> >> Fallback must happen exclusively under (IS_ERR(pb->pwm) && >> PTR_ERR(pb->pwm) != -EPROBE_DEFER && !pdev->dev.of_node) condition IMHO. >> >> Before EPROBE_DEFER appeared on the scene the condition was >> (IS_ERR(pb->pwm) && !pdev->dev.of_node). >> >> So, the question is if my change requires any updates or not from your >> point of view. > > ... but from a functional point of view your patch seems correct. Sounds good, thank you for review. Robert, because you found a regression in the related area of code on a platform, which uses legacy PWM API, could you please confirm that three patches applied in a row don't break anything for you, the changes are: * Nicolas' 68feaca0b1 ("backlight: pwm: Handle EPROBE_DEFER while requesting the PWM") * Thierry' https://lkml.org/lkml/2015/10/5/319 * and this one is the last in the series: http://thread.gmane.org/gmane.linux.pwm/2813 -- With best wishes, Vladimir