From: Daniel Thompson <daniel.thompson@linaro.org>
To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: "Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Lee Jones" <lee@kernel.org>, "Jingoo Han" <jingoohan1@gmail.com>,
"Helge Deller" <deller@gmx.de>,
linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] backlight: pwm_bl: Avoid backlight flicker applying initial PWM state
Date: Mon, 26 Jun 2023 16:05:14 +0100 [thread overview]
Message-ID: <20230626150514.GD95170@aspen.lan> (raw)
In-Reply-To: <20230608-backlight-pwm-avoid-flicker-v1-1-afd380d50174@pengutronix.de>
On Thu, Jun 08, 2023 at 04:11:14PM +0200, Philipp Zabel wrote:
> The initial PWM state returned by pwm_init_state() has a duty cycle
> of 0 ns. To avoid backlight flicker when taking over an enabled
> display from the bootloader, skip the initial pwm_apply_state()
> and leave the PWM be until backlight_update_state() will apply the
> state with the desired brightness.
backlight_update_state() uses pwm_get_state() to update the PWM.
Without applying something that came from pwm_init_state() then
we will never adopt the reference values from pwm->args.
Daniel.
next prev parent reply other threads:[~2023-06-26 15:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 14:11 [PATCH] backlight: pwm_bl: Avoid backlight flicker applying initial PWM state Philipp Zabel
2023-06-26 15:05 ` Daniel Thompson [this message]
2023-10-18 21:07 ` Uwe Kleine-König
2023-10-20 11:27 ` Daniel Thompson
2023-10-20 12:11 ` Uwe Kleine-König
2023-10-23 12:49 ` Daniel Thompson
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