Messages in this thread | | | Date | Thu, 19 Jul 2018 17:37:06 +0200 | From | Maxime Ripard <> | Subject | Re: [PATCH] drm/sun4i: Handle DRM_BUS_FLAG_PIXDATA_*EDGE checking if panel is used. |
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On Wed, Jul 18, 2018 at 04:23:57PM +0200, Giulio Benetti wrote: > Handle both positive and negative dclk polarity, > according to bus_flags, taking care of this: > > On A20 and similar SoCs, the only way to achieve Positive Edge > (Rising Edge), is setting dclk clock phase to 2/3(240°). > By default TCON works in Negative Edge(Falling Edge), this is why phase > is set to 0 in that case. > Unfortunately there's no way to logically invert dclk through IO_POL > register. > The only acceptable way to work, triple checked with scope, > is using clock phase set to 0° for Negative Edge and set to 240° for > Positive Edge. > On A33 and similar SoCs there would be a 90° phase option, but it divides > also dclk by 2. > This patch is a way to avoid quirks all around TCON and DOTCLOCK drivers > for using A33 90° phase divided by 2 and consequently increase code > complexity. > > Check if panel is used. TCON can also handle VGA DAC, then panel could > be empty. > > Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Applied, thanks
Maxime
-- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com [unhandled content-type:application/pgp-signature] | |