From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Date: Thu, 10 Nov 2016 08:16:15 +0000 Subject: Re: [PATCH v2] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_p Message-Id: <20161110081615.GO13127@dell> List-Id: References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <1477985147-18835-1-git-send-email-l.majewski@majess.pl> <20161108232525.639ea49f@jawa> In-Reply-To: <20161108232525.639ea49f@jawa> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: Lukasz Majewski Cc: Thierry Reding , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, Fabio Estevam , Fabio Estevam , linux-fbdev@vger.kernel.org, Liu Ying On Tue, 08 Nov 2016, Lukasz Majewski wrote: > Dear All, >=20 > > The commit a55944ca82d2 ("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 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 > COmments/acks are more than welcome :-) Ah, it looks like you dropped Jingoo from the list! I'll reply to the original mail with him in CC. > > Signed-off-by: Lukasz Majewski > > --- > > The patch has been tested on i.MX6q with 4.9-rc3 > > SHA1: a909d3e636995ba7c349e2ca5dbb528154d4ac30 > > --- > > Changes for v2: > > - Update commit message with proper other commit reference > >=20 > > --- > > drivers/video/backlight/pwm_bl.c | 10 +++++++++- > > 1 file changed, 9 insertions(+), 1 deletion(-) > >=20 > > 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 =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_device *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 --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog