From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Date: Tue, 24 Jan 2017 09:37:08 +0000 Subject: Re: [PATCH v2 RESEND] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_back Message-Id: <20170124093708.GV16020@dell> List-Id: References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <1482790896-29202-1-git-send-email-l.majewski@majess.pl> In-Reply-To: <1482790896-29202-1-git-send-email-l.majewski@majess.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable 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 On Mon, 26 Dec 2016, Lukasz Majewski wrote: > The commit a55944ca82d2=20 > ("backlight: update bd state & fb_blank properties when necessary") > has posed some extra restrictions on blanking and unblanking frame buffer > device. >=20 > Unfortunately, pwm_bl driver's probe did not initialize members of > struct backlight_device necessary for further blank/unblank operation. >=20 > This code in case of initial unblank of backlight device (default=20 > 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=20 > how much and which fb devices will be assigned). >=20 > 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. >=20 > 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(-) Applied with Thierry's crazy Ack. > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/p= wm_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 =3D FB_BLANK_UNBLANK; > struct pwm_args pargs; > - int ret; > + int ret, i; > =20 > if (!data) { > ret =3D pwm_backlight_parse_dt(&pdev->dev, &defdata); > @@ -348,6 +348,14 @@ static int pwm_backlight_probe(struct platform_devic= e *pdev) > =20 > bl->props.brightness =3D data->dft_brightness; > bl->props.power =3D initial_blank; > + > + if (initial_blank =3D FB_BLANK_UNBLANK) { > + for (i =3D 0; i < FB_MAX; i++) > + bl->fb_bl_on[i] =3D true; > + > + bl->use_count =3D 1; > + } > + > backlight_update_status(bl); > =20 > platform_set_drvdata(pdev, bl); --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog