Re: [PATCH v4 4/7] drm/panel: simple: Use display_timing for Innolux n116bge

From: "Heiko Stübner" <heiko@sntech.de>
To: Douglas Anderson <dianders@chromium.org>
Cc: "Rob Herring" <robh+dt@kernel.org>,
	"David Airlie" <airlied@linux.ie>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-rockchip@lists.infradead.org,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Sean Paul" <seanpaul@chromium.org>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Boris Brezillon" <boris.brezillon@collabora.com>,
	"Enric Balletbò" <enric.balletbo@collabora.com>,
	"Ezequiel Garcia" <ezequiel@collabora.com>,
	mka@chromium.org
Subject: Re: [PATCH v4 4/7] drm/panel: simple: Use display_timing for Innolux n116bge
Date: Fri, 29 Mar 2019 20:17:57 +0100	[thread overview]
Message-ID: <4434574.6rqfZtZq1D@diego> (raw)
In-Reply-To: <20190328171710.31949-5-dianders@chromium.org>

Am Donnerstag, 28. März 2019, 18:17:07 CET schrieb Douglas Anderson:
> Convert the Innolux n116bge from using a fixed mode to specifying a
> display timing with min/typ/max values.
> 
> Note that the n116bge's datasheet doesn't fit too well into DRM's way
> of specifying things.  Specifically the panel's datasheet just
> specifies the vertical blanking period and horizontal blanking period
> and doesn't break things out.  For now we'll leave everything as a
> fixed value but just allow adjusting the pixel clock.  I've added a
> comment on what the datasheet claims so someone could later expand
> things to fit their needs if they wanted to test other blanking
> periods.
> 
> The goal here is to be able to specify the panel timings in the device
> tree for several rk3288 Chromebooks (like rk3288-veryon-jerry).  These
> Chromebooks have all been running in the downstream kernel with the
> standard porches and sync lengths but just with a slightly slower
> pixel clock because the 76.42 MHz clock is not achievable from the
> fixed PLL that was available.  These Chromebooks only achieve a
> refresh rate of ~58 Hz.  While it's probable that we could adjust the
> timings to achieve 60 Hz it's probably wisest to match what's been
> running on these devices all these years.
> 
> I'll note that though the upstream kernel has always tried to achieve
> 76.42 MHz, it has actually been running at 74.25 MHz also since the
> video processor is parented off the same fixed PLL.
> 
> Changes in v4:
>  - display_timing for Innolux n116bge new for v4.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

on a rk3288-jerry and rk3288-pinky
Tested-by: Heiko Stuebner <heiko@sntech.de>


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