From: "Noralf Trønnes" <email@example.com> To: Marek Vasut <firstname.lastname@example.org>, Daniel Thompson <email@example.com> Cc: firstname.lastname@example.org, email@example.com, Meghana Madhyastha <firstname.lastname@example.org>, Sean Paul <email@example.com>, Thierry Reding <firstname.lastname@example.org> Subject: Re: [PATCH] video: backlight: Only set maximum brightness for gpio-backlight Date: Fri, 9 Jul 2021 15:25:29 +0200 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> Den 09.07.2021 15.19, skrev Marek Vasut: > On 7/9/21 1:03 PM, Daniel Thompson wrote: >> On Thu, Jul 08, 2021 at 11:10:58AM +0200, Marek Vasut wrote: >>> The note in c2adda27d202f ("video: backlight: Add of_find_backlight >>> helper >>> in backlight.c") says that gpio-backlight uses brightness as power >>> state. >>> Other backlight drivers do not, so limit this workaround to >>> gpio-backlight. >>> >>> This fixes the case where e.g. pwm-backlight can perfectly well be >>> set to >>> brightness 0 on boot in DT, which without this patch leads to the >>> display >>> brightness to be max instead of off. >>> >>> Fixes: c2adda27d202f ("video: backlight: Add of_find_backlight helper >>> in backlight.c") >>> Signed-off-by: Marek Vasut <email@example.com> >>> Cc: Daniel Thompson <firstname.lastname@example.org> >>> Cc: Meghana Madhyastha <email@example.com> >>> Cc: Noralf Trønnes <firstname.lastname@example.org> >>> Cc: Sean Paul <email@example.com> >>> Cc: Thierry Reding <firstname.lastname@example.org> >> >> I have to admit that this patch really does makes it clear just how >> nasty the hack in of_find_backlight() currently is. >> >> Moreover I think it is also be obsolete. gpio-backlight power mode >> handling was pretty broken when this code was introduced. It was fixed >> in 2019 by ec665b756e6f ("backlight: gpio backlight: Correct initial >> power state handling") by trying to match the behaviour of PWM >> backlight. The new code always sets the brightness to 1 so I think we >> can just remove the hack from of_find_backlight() since I think it is >> unreachable. > > I assume by "new code" you mean the fixed gpio-backlight driver ? > > Dropping the whole code after the Note: is fine by me. I haven't actually tested it, but when I saw the patch that Daniel points to, it looked like this work around could be removed. I haven't got time to tests it, but I will ack a patch that removes the hack. Noralf.
prev parent reply other threads:[~2021-07-09 13:25 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-08 9:10 Marek Vasut 2021-07-09 11:03 ` Daniel Thompson 2021-07-09 13:19 ` Marek Vasut 2021-07-09 13:25 ` Noralf Trønnes [this message]
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