Re: [PATCH 2/2] drm/panel: correct minimum hsync length of the HannStar HSD070PWW1 panel

[Lucas Stach <l.stach@pengutronix.de>]

Am Freitag, den 07.08.2015, 14:43 +0200 schrieb Thierry Reding:
> On Fri, Jun 26, 2015 at 12:27:09PM +0200, Lucas Stach wrote:
> > From: Philipp Zabel <p.zabel@pengutronix.de>
> > 
> > According to the data sheet, the minimum horizontal blanking interval
> > is 54 clocks (1 + 52 + 1), but tests with a Nitrogen6X have shown the
> > minimum working horizontal blanking interval to be 60 clocks.
> > 
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> > ---
> >  drivers/gpu/drm/panel/panel-simple.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> > index dc6a923c89d7..7196b940a928 100644
> > --- a/drivers/gpu/drm/panel/panel-simple.c
> > +++ b/drivers/gpu/drm/panel/panel-simple.c
> > @@ -713,7 +713,12 @@ static const struct display_timing hannstar_hsd070pww1_timing = {
> >  	.hactive = { 1280, 1280, 1280 },
> >  	.hfront_porch = { 1, 1, 10 },
> >  	.hback_porch = { 1, 1, 10 },
> > -	.hsync_len = { 52, 158, 661 },
> > +	/*
> > +	 * According to the data sheet, the minimum horizontal blanking interval
> > +	 * is 54 clocks (1 + 52 + 1), but tests with a Nitrogen6X have shown the
> > +	 * minimum working horizontal blanking interval to be 60 clocks.
> > +	 */
> > +	.hsync_len = { 58, 158, 661 },
> 
> 58 != 60, so which one is the truth here?
> 
The comment says blanking interval must be at least 60 clocks. Blanking
interval = front_porch + hsync_len + back_porch. Both minimum front and
back porch for this panel are 1 clock, so the values match the comment.

Regards,
Lucas

-- 
Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |

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