From: Enric Balletbo Serra <eballetbo@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>,
Lee Jones <lee.jones@linaro.org>,
Daniel Thompson <daniel.thompson@linaro.org>,
Jingoo Han <jingoohan1@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Heiko Stuebner <heiko@sntech.de>,
Thierry Reding <thierry.reding@gmail.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Richard Purdie <rpurdie@rpsys.net>,
Jacek Anaszewski <jacek.anaszewski@gmail.com>,
Linux PWM List <linux-pwm@vger.kernel.org>,
linux-fbdev@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Guenter Roeck <groeck@chromium.org>,
"open list:ARM/Rockchip SoC..."
<linux-rockchip@lists.infradead.org>,
linux-leds@vger.kernel.org,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
kernel@collabora.com
Subject: Re: [PATCH v6 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle.
Date: Mon, 26 Mar 2018 16:40:21 +0200 [thread overview]
Message-ID: <CAFqH_52fFLhuj6gkRNJsPozNfLSAKd0OpQKMjrdhqHRYU4xZ3Q@mail.gmail.com> (raw)
In-Reply-To: <20180326104205.GA12425@amd>
Hi Pavel,
2018-03-26 12:42 GMT+02:00 Pavel Machek <pavel@ucw.cz>:
> On Mon 2018-03-26 11:52:09, Enric Balletbo i Serra wrote:
>> Before this patch the enable signal was set before the PWM signal and
>> vice-versa on power off. This sequence is wrong, at least, it is on
>> the different panels datasheets that I checked, so I inverted the sequence
>> to follow the specs.
>>
>> For reference the following panels have the mentioned sequence:
>> - N133HSE-EA1 (Innolux)
>> - N116BGE (Innolux)
>> - N156BGE-L21 (Innolux)
>> - B101EAN0 (Auo)
>> - B101AW03 (Auo)
>> - LTN101NT05 (Samsung)
>> - CLAA101WA01A (Chunghwa)
>
> Ok, but this changes behaviour for other panels, too. Are you sure you
> are not breaking one of those?
I can't say that I am 100% sure because I didn't find all the
datasheets of all the panels supported in the kernel. But all the
datasheets I checked specifies this sequence as valid. In general I
think that doesn't really matter, but I know that at least the
B116XTN02 panel requires enable first the PWM, wait 10ms and then
enable BL_EN to avoid garbage. So the other way around is not valid
for this panel. That's the reason for this patchset.
If anyone knows a panel that says the contrary, please let me know and
I'll try to rework the patches to satisfy both requirements.
Regards,
Enric
> Pavel
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2018-03-26 14:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 9:52 [PATCH v6 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle Enric Balletbo i Serra
[not found] ` <20180326095213.18362-1-enric.balletbo-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
2018-03-26 9:52 ` [PATCH v6 2/5] dt-bindings: pwm-backlight: add PWM delay proprieties Enric Balletbo i Serra
2018-03-26 15:07 ` Daniel Thompson
2018-03-27 15:08 ` Rob Herring
2018-03-26 9:52 ` [PATCH v6 3/5] pwm-backlight: add support for PWM delays proprieties Enric Balletbo i Serra
2018-03-26 9:52 ` [PATCH v6 5/5] ARM: dts: rockchip: set PWM delay backlight settings for Minnie Enric Balletbo i Serra
2018-03-26 9:52 ` [PATCH v6 4/5] ARM: dts: rockchip: set PWM delay backlight settings for Veyron Enric Balletbo i Serra
2018-03-26 10:42 ` [PATCH v6 1/5] pwm-backlight: enable/disable the PWM before/after LCD enable toggle Pavel Machek
2018-03-26 14:40 ` Enric Balletbo Serra [this message]
2018-03-26 15:18 ` Daniel Thompson
2018-03-28 11:12 ` Lee Jones
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