Re: [PATCH v4, 1/4] drm/mediatek: Adjust the timing of mipi signal from LP00 to LP11

[xinlei.lee <xinlei.lee@mediatek.com>]

On Wed, 2022-04-13 at 09:59 +0800, CK Hu wrote:
> Hi, Xinlei:
> 
> On Mon, 2022-04-11 at 10:31 +0800, xinlei.lee@mediatek.com wrote:
> > From: Jitao Shi <jitao.shi@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
> > 
> > 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
> 
> You just describe WHAT this patch do, but WHY this patch do? Does
> this
> patch reorder sequence to follow any spec?
> 
> > 
> > Fixes: 2dd8075d2185 ("drm/mediatek: mtk_dsi: Use the
> > drm_panel_bridge
> > API")
> > 
> > Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> > Signed-off-by: Xinlei Lee <xinlei.lee@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);
> 
> The original sequence is done by patch [1] not the patch in the Fixes
> tag. So modify the Fixes tag.
> 
> [1] 
> 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/mediatek/mtk_dsi.c?h=v5.18-rc2&id=75374fc2c152ef42c45c6bf716743d5f5bb6d24d
> 
> Regards,
> CK
> 
> >  	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!
This modification does not violate the spec. The main purpose is to
move 2, 3, 4 of the new sequece to the lane_ready function.
I will modify this Fixes tag in the next version.

Best Regards!
xinlei