From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Date: Tue, 08 Nov 2016 22:25:25 +0000 Subject: Re: [PATCH v2] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_p Message-Id: <20161108232525.639ea49f@jawa> MIME-Version: 1 Content-Type: multipart/mixed; boundary="Sig_/NyEX8F8KHl9JxWarQvsi.WO" List-Id: References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <1477985147-18835-1-git-send-email-l.majewski@majess.pl> In-Reply-To: <1477985147-18835-1-git-send-email-l.majewski@majess.pl> To: Thierry Reding , Lee Jones , Jean-Christophe Plagniol-Villard , Tomi Valkeinen Cc: linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, Fabio Estevam , Fabio Estevam , linux-fbdev@vger.kernel.org, Liu Ying --Sig_/NyEX8F8KHl9JxWarQvsi.WO Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Dear All, > 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. COmments/acks are more than welcome :-) Best regards, =C5=81ukasz Majewski >=20 > 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=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); --Sig_/NyEX8F8KHl9JxWarQvsi.WO Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlgiUNwACgkQf9/hG2YwgjHfgwCggyLwAKP8bo3UD/ZFlqWJTzYX rnwAoKjiSoTaRrAXB3uXPwJUpCRcUs2g =RiCW -----END PGP SIGNATURE----- --Sig_/NyEX8F8KHl9JxWarQvsi.WO--