[PATCH v3, 1/4] drm/mediatek: Adjust the timing of mipi signal from LP00 to LP11

[xinlei.lee]

On Mon, 2022-03-21 at 17:36 +0800, CK Hu wrote:
> Hi, Xinlei:
> 
> On Thu, 2022-03-17 at 15:53 +0800, xinlei.lee at mediatek.com wrote:
> > From: Jitao Shi <jitao.shi at mediatek.com>
> > 
> > Old sequence:
> > 1. Pull the MIPI signal high
> > 2. Delay & Dsi_reset
> > 3. Set the dsi timing register
> > 4. dsi clk & lanes leave ulp mode and enter hs mode
> > 
> > New sequence:
> > 1. Set the dsi timing register
> > 2. Pull the MIPI signal high
> > 3. Delay & Dsi_reset
> > 4. dsi clk & lanes leave ulp mode and enter hs mode
> > 
> > In the new sequence 2 & 3 & 4 will be moved to dsi_enbale in later
> > patch.
> 
> I think there would be one patch in 5.9 make the wrong sequence, so
> add
> 'Fixes' tag to indicate which patch make the wrong sequence. Use the
> term correct/wrong instead old/new sequence.
> 
> I still do not understand what is the sequence after apply this
> patch?
> 
> Does the sequence is this after apply this patch?
> 1. Set the dsi timing register
> 2. Pull the MIPI signal high
> 3. Delay & Dsi_reset
> 4. dsi clk & lanes leave ulp mode and enter hs mode
> 
> Regards,
> CK
> 
> > 
> > Signed-off-by: Jitao Shi <jitao.shi at mediatek.com>
> > Signed-off-by: Xinlei Lee <xinlei.lee at mediatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dsi.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index ccb0511b9cd5..262c027d8c2f 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -649,14 +649,14 @@ static int mtk_dsi_poweron(struct mtk_dsi
> > *dsi)
> >  	mtk_dsi_reset_engine(dsi);
> >  	mtk_dsi_phy_timconfig(dsi);
> >  
> > -	mtk_dsi_rxtx_control(dsi);
> > -	usleep_range(30, 100);
> > -	mtk_dsi_reset_dphy(dsi);
> >  	mtk_dsi_ps_control_vact(dsi);
> >  	mtk_dsi_set_vm_cmd(dsi);
> >  	mtk_dsi_config_vdo_timing(dsi);
> >  	mtk_dsi_set_interrupt_enable(dsi);
> >  
> > +	mtk_dsi_rxtx_control(dsi);
> > +	usleep_range(30, 100);
> > +	mtk_dsi_reset_dphy(dsi);
> >  	mtk_dsi_clk_ulp_mode_leave(dsi);
> >  	mtk_dsi_lane0_ulp_mode_leave(dsi);
> >  	mtk_dsi_clk_hs_mode(dsi, 0);
> 
> 

Hi CK:

Thanks for your review!

You are right, the sequence after patching is:
1. Set the dsi timing register
2. Pull the MIPI signal high
3. Delay & Dsi_reset
4. dsi clk & lanes leave ulp mode and enter hs mode

This modification will not affect the dsi function, just to put the
operation of pulling up the mipi signal in poweron together to
facilitate the separation from the poweron function later.

I will add the "Fixes" tag here as well.

BR!
xinlei