From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jingoo Han" Date: Tue, 25 Oct 2016 22:47:00 +0000 Subject: Re: [PATCH] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_prob Message-Id: <000d01d22f11$b333ed80$199bc880$@gmail.com> List-Id: References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <000201d22d9f$22acb6c0$68062440$@gmail.com> <20161024230041.41959e5e@jawa> In-Reply-To: <20161024230041.41959e5e@jawa> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1254" Content-Transfer-Encoding: base64 To: 'Lukasz Majewski' Cc: 'Thierry Reding' , 'Lee Jones' , 'Jean-Christophe Plagniol-Villard' , 'Tomi Valkeinen' , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, 'Fabio Estevam' , 'Fabio Estevam' , 'Liu Ying' T24gTW9uZGF5LCBPY3RvYmVyIDI0LCAyMDE2LCBMdWthc3ogTWFqZXdza2kgd3JvdGU6Cj4gCj4g SGkgSmluZ29vLAo+IAo+ID4gT24gU2F0dXJkYXksIE9jdG9iZXIgMjIsIDIwMTYsIEx1a2FzeiBN 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"Jingoo Han" Subject: Re: [PATCH] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe() Date: Tue, 25 Oct 2016 18:47:00 -0400 Message-ID: <000d01d22f11$b333ed80$199bc880$@gmail.com> References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <000201d22d9f$22acb6c0$68062440$@gmail.com> <20161024230041.41959e5e@jawa> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mail-qk0-f193.google.com ([209.85.220.193]:35311 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbcJYWrD (ORCPT ); Tue, 25 Oct 2016 18:47:03 -0400 In-Reply-To: <20161024230041.41959e5e@jawa> Content-Language: ko Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: 'Lukasz Majewski' Cc: 'Thierry Reding' , 'Lee Jones' , 'Jean-Christophe Plagniol-Villard' , 'Tomi Valkeinen' , linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, 'Fabio Estevam' , 'Fabio Estevam' , 'Liu Ying' On Monday, October 24, 2016, Lukasz Majewski wrote: >=20 > Hi Jingoo, >=20 > > On Saturday, October 22, 2016, Lukasz Majewski wrote: > > > > > > The commit: a55944ca82d287ca099ca90413af857af9086773 has posed = some > > > extra Please add the 'subject' of patch as below. The commit a55944ca82d2 ("backlight: update bd state & fb_blank = properties when necessary ") has posted some extra. Best regards, Jingoo Han > > > > Please add the subject of the patch, in order to let people know > > which patch you mention exactly. Please loot at other commits that > > fixed bugs or behavior > > of other patches. >=20 > Thanks for the tip. >=20 > The mentioned patch: >=20 > commit a55944ca82d287ca099ca90413af857af9086773 > Author: Liu Ying > Date: Thu Apr 3 14:48:54 2014 -0700 >=20 > backlight: update bd state & fb_blank properties when necessary >=20 > We don't have to update the state and fb_blank properties of a > backlight > device every time a blanking or unblanking event comes because = they > may > have already been what we want. Another thought is that one = backlight > device may be shared by multiple framebuffers. The backlight = driver > should take the backlight device as a resource shared by all the > associated framebuffers. >=20 > This patch adds some logic to record each framebuffer's backlight > usage > to determine the backlight device use count and whether the two > properties should be updated or not. To be more specific, only = one > unblank operation on a certain blanked framebuffer may increase = the > backlight device's use count by one, while one blank operation on = a > certain unblanked framebuffer may decrease the use count by one, > because > the userspace is likely to unblank an unblanked framebuffer or = blank a > blanked framebuffer. >=20 >=20 > Could you provide more feedback regarding provided fix? >=20 > Thanks in advance, >=20 > =C5=81ukasz Majewski >=20 > > > > > 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 4.7 and 4.8 > > > kernels. It applies on 4.9-rcX SHA1: > > > dcd4693cf47801b7d988ea897519de90dfd25d17. > > > > > > --- > > > 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 8040fd6..def39e8 100644 > > > --- a/drivers/video/backlight/pwm_bl.c > > > +++ b/drivers/video/backlight/pwm_bl.c > > > @@ -203,7 +203,7 @@ 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; > > > > > > if (!data) { > > > ret =3D pwm_backlight_parse_dt(&pdev->dev, > > > &defdata); @@ - 349,6 +349,14 @@ static int > > > pwm_backlight_probe(struct platform_device *pdev) > > > > > > 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); > > > > > > platform_set_drvdata(pdev, bl); > > > -- > > > 2.1.4 > > > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755398AbcJYWrG (ORCPT ); Tue, 25 Oct 2016 18:47:06 -0400 Received: from mail-qk0-f193.google.com ([209.85.220.193]:35311 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbcJYWrD (ORCPT ); Tue, 25 Oct 2016 18:47:03 -0400 From: "Jingoo Han" To: "'Lukasz Majewski'" Cc: "'Thierry Reding'" , "'Lee Jones'" , "'Jean-Christophe Plagniol-Villard'" , "'Tomi Valkeinen'" , , , , "'Fabio Estevam'" , "'Fabio Estevam'" , "'Liu Ying'" References: <1477169904-14997-1-git-send-email-l.majewski@majess.pl> <000201d22d9f$22acb6c0$68062440$@gmail.com> <20161024230041.41959e5e@jawa> In-Reply-To: <20161024230041.41959e5e@jawa> Subject: Re: [PATCH] video: backlight: pwm_bl: Initialize fb_bl_on[x] and use_count during pwm_backlight_probe() Date: Tue, 25 Oct 2016 18:47:00 -0400 Message-ID: <000d01d22f11$b333ed80$199bc880$@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQFuVu1LFZrUmS0lbSNwmb65HVLaMQGkNKeGAdndrZShZYQi0A== Content-Language: ko Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id u9PMlEch025866 On Monday, October 24, 2016, Lukasz Majewski wrote: > > Hi Jingoo, > > > On Saturday, October 22, 2016, Lukasz Majewski wrote: > > > > > > The commit: a55944ca82d287ca099ca90413af857af9086773 has posed some > > > extra Please add the 'subject' of patch as below. The commit a55944ca82d2 ("backlight: update bd state & fb_blank properties when necessary ") has posted some extra. Best regards, Jingoo Han > > > > Please add the subject of the patch, in order to let people know > > which patch you mention exactly. Please loot at other commits that > > fixed bugs or behavior > > of other patches. > > Thanks for the tip. > > The mentioned patch: > > commit a55944ca82d287ca099ca90413af857af9086773 > Author: Liu Ying > Date: Thu Apr 3 14:48:54 2014 -0700 > > backlight: update bd state & fb_blank properties when necessary > > We don't have to update the state and fb_blank properties of a > backlight > device every time a blanking or unblanking event comes because they > may > have already been what we want. Another thought is that one backlight > device may be shared by multiple framebuffers. The backlight driver > should take the backlight device as a resource shared by all the > associated framebuffers. > > This patch adds some logic to record each framebuffer's backlight > usage > to determine the backlight device use count and whether the two > properties should be updated or not. To be more specific, only one > unblank operation on a certain blanked framebuffer may increase the > backlight device's use count by one, while one blank operation on a > certain unblanked framebuffer may decrease the use count by one, > because > the userspace is likely to unblank an unblanked framebuffer or blank a > blanked framebuffer. > > > Could you provide more feedback regarding provided fix? > > Thanks in advance, > > Łukasz Majewski > > > > > > 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 4.7 and 4.8 > > > kernels. It applies on 4.9-rcX SHA1: > > > dcd4693cf47801b7d988ea897519de90dfd25d17. > > > > > > --- > > > 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 8040fd6..def39e8 100644 > > > --- a/drivers/video/backlight/pwm_bl.c > > > +++ b/drivers/video/backlight/pwm_bl.c > > > @@ -203,7 +203,7 @@ 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); @@ - 349,6 +349,14 @@ 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); > > > -- > > > 2.1.4 > > > >