[PATCH v3,3/4] drm/mediatek: keep dsi as LP00 before dcs cmds transfer

[xinlei.lee]

On Thu, 2022-03-17 at 20:06 +0800, Rex-BC Chen wrote:
> Hello Xinlei,
> 
> On Thu, 2022-03-17 at 15:53 +0800, xinlei.lee at mediatek.com wrote:
> > From: Jitao Shi <jitao.shi at mediatek.com>
> > 
> > To comply with the panel sequence, hold the mipi signal to LP00 
> 
> Could you provide a example panel power sequence to let me understand
> that?
> Maybe you can put them in commit message.
> 
> > before the dcs cmds transmission,
> > and pull the mipi signal high from LP00 to LP11 until the start of
> > the dcs cmds transmission.
> 
> Maybe you can try to write as:
> To comply with...
> - Hold the mipi signal...
> - Pul the miip signal high....
> 
> > If dsi is not in cmd mode, then dsi will pull the mipi signal high
> > in
> > the mtk_output_dsi_enable function.
> > 
> > Fixes: 2dd8075d2185 ("drm/mediatek: mtk_dsi: Use the
> > drm_panel_bridge
> > API")
> > 
> 
> Can you remove this blank line?
> 
> > 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 | 31 +++++++++++++++++++++++---
> > --
> > --
> >  1 file changed, 24 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index e33caaca11a7..b509d59235e2 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -203,6 +203,7 @@ struct mtk_dsi {
> >  	struct mtk_phy_timing phy_timing;
> >  	int refcount;
> >  	bool enabled;
> > +	bool lanes_ready;
> >  	u32 irq_data;
> >  	wait_queue_head_t irq_wait_queue;
> >  	const struct mtk_dsi_driver_data *driver_data;
> > @@ -654,13 +655,6 @@ static int mtk_dsi_poweron(struct mtk_dsi
> > *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);
> > -
> >  	return 0;
> >  err_disable_engine_clk:
> >  	clk_disable_unprepare(dsi->engine_clk);
> > @@ -689,6 +683,8 @@ static void mtk_dsi_poweroff(struct mtk_dsi
> > *dsi)
> >  	clk_disable_unprepare(dsi->digital_clk);
> >  
> >  	phy_power_off(dsi->phy);
> > +
> > +	dsi->lanes_ready = false;
> >  }
> >  
> >  static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
> > @@ -696,6 +692,16 @@ static void mtk_output_dsi_enable(struct
> > mtk_dsi
> > *dsi)
> >  	if (dsi->enabled)
> >  		return;
> >  
> > +	if (!dsi->lanes_ready) {
> > +		dsi->lanes_ready = true;
> > +		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);
> > +	}
> > +
> >  	mtk_dsi_set_mode(dsi);
> >  	mtk_dsi_clk_hs_mode(dsi, 1);
> >  
> > @@ -995,6 +1001,17 @@ static ssize_t mtk_dsi_host_transfer(struct
> > mipi_dsi_host *host,
> >  	if (MTK_DSI_HOST_IS_READ(msg->type))
> >  		irq_flag |= LPRX_RD_RDY_INT_FLAG;
> >  
> > +	if (!dsi->lanes_ready) {
> > +		dsi->lanes_ready = true;
> > +		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);
> 
> The drivers are the same with previous modification.
> I think you can use a funtion for them?
> 
> > +		msleep(20);
> 
> Why delay 20ms but not in mtk_output_dsi_enable?
> 
> BRs,
> Rex
> > +	}
> > +
> >  	ret = mtk_dsi_host_send_cmd(dsi, msg, irq_flag);
> >  	if (ret)
> >  		goto restore_dsi_mode;
> 
> 

Hi rex:

Thanks for your review.

1.The normal panel timing is as follows (I will add to the commit
message in the next version):
(1) pp1800 DC pull up
(2) avdd & avee AC pull high
(3) lcm_reset pull high -> pull low -> pull high
(4) Pull MIPI signal high (LP11) -> initial code -> send video data(HS
mode)
The power-off sequence is reversed.

2.
The 20ms delay in dsi_host_transfer is because dsi needs to give
dsi_rx(panel) a reaction time after pulling up the mipi signal.
If you suggest encapsulating it as a function I will add a delay to
mtk_output_dsi_enable in the next version as well.
Best Regards!
xinlei