Hi Marjan,
On 1/8/21 10:32 AM, Marjan Pascolo wrote:
Hi,
please don't top post, answer in-line as we do, and please use plain-test instead of HTML. These are the standards in Mailing Lists(ML).
Quote "
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
"
Already answered to Maxime
And another question (probably could be a stupid one):
in "/[PATCH v2 2/2] drm/sun4i: tcon: improve DCLK polarity handling/" I see you deleted:
clk_set_phase(tcon->dclk, 0);Is safe to assume that phase register will be always set to 0?
We always assumed it is set to 0 by default.
Or maybe will be safer manually set it to 0 in every condition to avoid surprises (dirt values due to previous condition)?
That would be a good idea, so something like this:
''' int phase = 0;
if (info->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) phase = 240;
clk_set_phase(tcon->dclk, phase); '''
because now DRM_BUS_FLAG_PIXDATA_SAMPLE_ and DRM_BUS_FLAG_PIXDATA_DRIVE_ are exclusive, while before not.
But then if bit 26 solution works everything gets easier.
Best Regards Giulio
Marjan
Il 08/01/2021 10:23, Maxime Ripard ha scritto:
Hi,
Thanks for those patches
On Thu, Jan 07, 2021 at 03:30:32AM +0100, Giulio Benetti wrote:
From: Giulio Benettigiulio.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 Ripardmaxime@cerno.tech
Suggested-by would be nice here :)
Signed-off-by: Giulio Benettigiulio.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.*/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