Re: [PATCH v2 11/11] drm/rockchip/dsi: fix insufficient bandwidth of some panel

[Chris Zhong]

Hi John

On 01/17/2017 06:54 PM, John Keeping wrote:
> On Tue, 17 Jan 2017 17:31:53 +0800, Chris Zhong wrote:
>
> > On 01/16/2017 08:44 PM, John Keeping wrote:
> > > On Mon, 16 Jan 2017 18:08:31 +0800, Chris Zhong wrote:
> > >   
> > > > Set the lanes bps to 1 / 0.9 times of pclk, the margin is not enough
> > > > for some panel, it will cause the screen display is not normal, so
> > > > increases the badnwidth to 1 / 0.8.
> > > >
> > > > Signed-off-by: Chris Zhong <zyw@xxxxxxxxxxxxxx>
> > > >
> > > > ---
> > > >
> > > >    drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 4 ++--
> > > >    1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> > > > index 9dfa73d..5a973fe 100644
> > > > --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> > > > +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> > > > @@ -501,8 +501,8 @@ static int dw_mipi_dsi_get_lane_bps(struct dw_mipi_dsi *dsi)
> > > >    
> > > >    	mpclk = DIV_ROUND_UP(dsi->mode->clock, MSEC_PER_SEC);
> > > >    	if (mpclk) {
> > > > -		/* take 1 / 0.9, since mbps must big than bandwidth of RGB */
> > > > -		tmp = mpclk * (bpp / dsi->lanes) * 10 / 9;
> > > > +		/* take 1 / 0.8, since mbps must big than bandwidth of RGB */
> > > > +		tmp = mpclk * (bpp / dsi->lanes) * 10 / 8;
> > > This and patch 9 are just hacking around the underlying problem in order
> > > to make particular panels work.  I'm pretty sure the actual issue is the
> > > use of hardcoded values when configuring the PHY, since the PHY
> > > parameters are specified in clock cycles but the MIPI spec requires
> > > absolute time durations.
> > >
> > > I posted a series addressing this a while ago, although I screwed up
> > > sending it so some patches were included twice and since no one
> > > expressed any interest I didn't post a cleaned up version.
> > >
> > > The relevant patch is here:
> > >
> > > https://patchwork.kernel.org/patch/9340193/
> > Thanks very much, your patches are very useful for me. It looks your
> > method is correct.
> > And I am very confused why Mark Yao and me did not receive your patches
> > before,
> > although we have subscribed the <linux-rockchip@xxxxxxxxxxxxxxxxxxx>.
> >
> > In addition, could you tell me which device ware you testing with these
> > mipi patches.
> > I going to test them these day.
> I'm using RK3288 and I tested my patches with three different MIPI
> displays, two of which require commands to be sent in order to set up
> the panel.
>
> Thanks for testing the patches.
>
>
> John
I think we really need this patch, one mipi panel hit this problem 
again, with all your 24 patches
and my 6 MIPI DSI patches
So I will update my series to v7, and add this patch into it.

>