[PATCH v4, 3/4] drm/mediatek: keep dsi as LP00 before dcs cmds transfer

[CK Hu]

Hi, Xinlei:

On Fri, 2022-04-15 at 09:58 +0800, xinlei.lee wrote:
> On Wed, 2022-04-13 at 16:31 +0800, CK Hu wrote:
> > Hi, Xinlei:
> > 
> > On Mon, 2022-04-11 at 10:31 +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
> > > before the dcs cmds transmission,
> > > and pull the mipi signal high from LP00 to LP11 until the start
> > > of
> > > the dcs cmds transmission.
> > > The normal panel timing is :
> > > (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.
> > > 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")
> > > 
> > > 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 | 28 +++++++++++++++++++++---
> > > --
> > > --
> > >  1 file changed, 21 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > > index cf76c53a1af6..9ad6f08c8bfe 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 +683,23 @@ 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_dsi_lane_ready(struct mtk_dsi *dsi)
> > > +{
> > > +	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);
> > > +		msleep(20);
> > > +	} else
> > > +		DRM_DEBUG("The dsi_lane is ready\n");

Once mtk_dsi_host_transfer() call this function first, then
mtk_output_dsi_enable() would call again. This function would be called
twice in normal sequence, so I think this debug information is not
necessary.

> > >  }
> > >  
> > >  static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
> > > @@ -696,6 +707,7 @@ static void mtk_output_dsi_enable(struct
> > > mtk_dsi
> > > *dsi)
> > >  	if (dsi->enabled)
> > >  		return;
> > >  
> > > +	mtk_dsi_lane_ready(dsi);
> > >  	mtk_dsi_set_mode(dsi);
> > >  	mtk_dsi_clk_hs_mode(dsi, 1);
> > >  
> > > @@ -1001,6 +1013,8 @@ 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;
> > >  
> > > +	mtk_dsi_lane_ready(dsi);
> > 
> > In [1], YT has move mtk_dsi_lane_ready() before panel prepare for
> > dsi-
> > > panel case. Now you move mtk_dsi_lane_ready() after panel
> > > prepare,
> > 
> > this may break dsi->panel case. Please provide a solution for both
> > case.
> > 
> > [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=0707632b5bacc490f58dfbad741d586c06595ff3
> > 
> > Regards,
> > CK
> > 
> > > +
> > >  	ret = mtk_dsi_host_send_cmd(dsi, msg, irq_flag);
> > >  	if (ret)
> > >  		goto restore_dsi_mode;
> > 
> > 
> 
> Hi CK:
> 
> Because the order of dsi->panel in [1] is as follows (tv101 panel as
> an
> example):
> 1. dsi_poweron (lane_ready)
> 2. panel_prepare
> 3. panel_prepare_power
> 4. panel_init_cmd
> 5. dsi_host_transfer (actually send panel initial code)
> 
> This modified order:
> 1. dsi_poweron
> 2. panel_prepare
> 3. panel_prepare_power
> 4. panel_init_cmd
> 5. dsi_host_transfer (lane_ready)
> 
> It can be seen that the lane_ready is delayed closer to before
> sending
> the initial code, which is necessary for some panels with stricter
> timing requirements.
> And if this screen does not need to send initial code, it will also
> do
> lane_ready in output_dsi_enable, so that dsi can complete LP00->LP11-
> > HS mode.

Understand. You call mtk_dsi_lane_ready() in both
mtk_output_dsi_enable() and mtk_dsi_host_transfer(). The panel prepare
may call mtk_dsi_host_transfer() and mtk_dsi_lane_ready() would be
called.

Regards,
CK

> 
> [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=0707632b5bacc490f58dfbad741d586c06595ff3
> 
> Best Regards!
> xinlei
>