From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe() Date: Tue, 3 Jan 2017 08:30:32 +0000 Message-ID: <20170103083032.GA2977@dell> References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <1482790896-29202-1-git-send-email-l.majewski@majess.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Received: from mail-wm0-f49.google.com ([74.125.82.49]:36164 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934292AbdACI0w (ORCPT ); Tue, 3 Jan 2017 03:26:52 -0500 Received: by mail-wm0-f49.google.com with SMTP id c85so193932596wmi.1 for ; Tue, 03 Jan 2017 00:26:51 -0800 (PST) Content-Disposition: inline In-Reply-To: <1482790896-29202-1-git-send-email-l.majewski@majess.pl> Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: Lukasz Majewski Cc: Thierry Reding , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, Liu Ying , Fabio Estevam , Fabio Estevam , Jingoo Han , Tomi Valkeinen Thierry, Jingoo, Please respond to Lukasz. On Mon, 26 Dec 2016, Lukasz Majewski wrote: > The commit a55944ca82d2 > ("backlight: update bd state & fb_blank properties when necessary") > has posed some extra restrictions on blanking and unblanking frame buffer > device. > > Unfortunately, pwm_bl driver's probe did not initialize members of > struct backlight_device necessary for further blank/unblank operation. > > This code in case of initial unblank of backlight device (default > behaviour) sets use_count to 1 and marks this particular backlight device > as used by all available fb devices (since it is not known during probe > how much and which fb devices will be assigned). > > Without this code, the backlight works properly until one tries to blank it > manually from sysfs with "echo 1 > /sys/class/graphics/fb0/blank". > Since fb_bl_on[0] and use_count were both set to 0, the logic at > fb_notifier_callback (@backlight.c) thought that we didn't turn on > (unblanked) the backlight device and refuses to disable (blank) it. > As a result we see garbage from fb displayed. > > Signed-off-by: Lukasz Majewski > --- > The patch has been tested on i.MX6q with vanilla 4.9 kernel. > It applies on 4.10-rc1. > --- > drivers/video/backlight/pwm_bl.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c > index 1261400..6859ba0 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -202,7 +202,7 @@ static int pwm_backlight_probe(struct platform_device *pdev) > struct pwm_bl_data *pb; > int initial_blank = FB_BLANK_UNBLANK; > struct pwm_args pargs; > - int ret; > + int ret, i; > > if (!data) { > ret = pwm_backlight_parse_dt(&pdev->dev, &defdata); > @@ -348,6 +348,14 @@ static int pwm_backlight_probe(struct platform_device *pdev) > > bl->props.brightness = data->dft_brightness; > bl->props.power = initial_blank; > + > + if (initial_blank == FB_BLANK_UNBLANK) { > + for (i = 0; i < FB_MAX; i++) > + bl->fb_bl_on[i] = true; > + > + bl->use_count = 1; > + } > + > backlight_update_status(bl); > > platform_set_drvdata(pdev, bl); -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog