From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Date: Mon, 02 Sep 2019 09:11:30 +0000 Subject: Re: [PATCH v3] backlight: gpio-backlight: Correct initial power state handling Message-Id: <20190902091130.GG32232@dell> List-Id: References: <20190731084018.5318-1-peter.ujfalusi@ti.com> In-Reply-To: <20190731084018.5318-1-peter.ujfalusi@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Peter Ujfalusi Cc: daniel.thompson@linaro.org, jingoohan1@gmail.com, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, paul.kocialkowski@bootlin.com On Wed, 31 Jul 2019, Peter Ujfalusi wrote: > The default-on property - or the def_value via legacy pdata) should be > handled as: > if it is 1, the backlight must be enabled (kept enabled) > if it is 0, the backlight must be disabled (kept disabled) > > This only works for the case when default-on is set. If it is not set then > the brightness of the backlight is set to 0. Now if the backlight is > enabled by external driver (graphics) the backlight will stay disabled since > the brightness is configured as 0. The backlight will not turn on. > > In order to minimize screen flickering during device boot: > > The initial brightness should be set to 1. > > If booted in non DT mode or no phandle link to the backlight node: > follow the def_value/default-on to select UNBLANK or POWERDOWN > > If in DT boot we have phandle link then leave the GPIO in a state which the > bootloader left it and let the user of the backlight to configure it > further. > > Signed-off-by: Peter Ujfalusi > --- > Hi, > > sorry for the delay, but got distracted a bit with the resend of this... > Let's try again ;) > > Changes since v2 (https://lore.kernel.org/patchwork/patch/1002359/): > - Rebased on drm-next > > Changes since v1: > - Implement similiar initial power state handling as pwm backlight have > > Regards, > Peter > > drivers/video/backlight/gpio_backlight.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) Applied, thanks. -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog