Messages in this thread | | | Date | Fri, 8 Jan 2021 10:23:55 +0100 | From | Maxime Ripard <> | Subject | Re: [PATCH v2 2/2] drm/sun4i: tcon: improve DCLK polarity handling |
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Hi,
Thanks for those patches
On Thu, Jan 07, 2021 at 03:30:32AM +0100, Giulio Benetti wrote: > From: Giulio Benetti <giulio.benetti@micronovasrl.com> > > It turned out(Maxime suggestion) that bit 26 of SUN4I_TCON0_IO_POL_REG is > dedicated to invert DCLK polarity and this makes thing really easier than > before. So let's handle DCLK polarity by adding > SUN4I_TCON0_IO_POL_DCLK_POSITIVE as bit 26 and activating according to > bus_flags the same way is done for all the other signals. > > Cc: Maxime Ripard <maxime@cerno.tech>
Suggested-by would be nice here :)
> Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com> > --- > drivers/gpu/drm/sun4i/sun4i_tcon.c | 20 +------------------- > drivers/gpu/drm/sun4i/sun4i_tcon.h | 1 + > 2 files changed, 2 insertions(+), 19 deletions(-) > > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c > index 52598bb0fb0b..30171ccd87e5 100644 > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c > @@ -569,26 +569,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon, > if (info->bus_flags & DRM_BUS_FLAG_DE_LOW) > val |= SUN4I_TCON0_IO_POL_DE_NEGATIVE; > > - /* > - * 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. > - * Following code is a way to avoid quirks all around TCON > - * and DOTCLOCK drivers. > - */ > if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE) > - clk_set_phase(tcon->dclk, 0); > - > - if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) > - clk_set_phase(tcon->dclk, 240); > + val |= SUN4I_TCON0_IO_POL_DCLK_POSITIVE;
I'm not really sure why we need the first patch of this series here? That patch only seem to undo what you did in patch 1
Maxime
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