Re: [PATCH 3/4] drm/mediatek: fine tune the dsi panel's power sequence

[Jitao Shi <jitao.shi@mediatek.com>]

On Sat, 2021-04-24 at 00:36 +0800, Chun-Kuang Hu wrote:
> Hi, Jitao:
> 
> Jitao Shi <jitao.shi@mediatek.com> 於 2021年4月20日 週二 下午9:26寫道：
> >
> > Add the drm_panel_prepare_power and drm_panel_unprepare_power control.
> > Turn on panel power(drm_panel_prepare_power) and control before dsi
> > enable. And then dsi enable, send dcs cmd in drm_panel_prepare, last
> > turn on backlight.
> 
> Please describe WHY do you need this patch? Fix any bug?

Most panels, have five steps when poweron.

1. turn on dsi signal to LP11   --> dsi host's action
2. turn on the power supplies,  --> panel's action
3. send the DCS  cmd to panel   --> panel's action
4. start send video stream      --> dsi host's action
5. turn on backlight.           --> panel's action

we put "turn on the power supplies" and "send the DCS  cmd to panel" in
panel_prepare. And "turn on backlight" in panel_enable.

But some other panels has a special poweron sequence as the following.

1. turn on the power supplies,  --> panel's action
2. turn on dsi signal to LP11   --> dsi host's action
3. send the DCS  cmd to panel   --> panel's action
4. start send video stream      --> dsi host's action
5. turn on backlight.           --> panel's action

panel's actions are divided into three parts.

So I add a new api "drm_panel_prepare_power/rm_panel_unprepare_power" to
control the sequence.


Best Regards
Jitao

> 
> >
> > Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dsi.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index a1ff152ef468..455fe582c6b5 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -615,10 +615,13 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
> >         dsi->data_rate = DIV_ROUND_UP_ULL(dsi->vm.pixelclock * bit_per_pixel,
> >                                           dsi->lanes);
> >
> > +       if (panel_bridge_prepare_power(dsi->next_bridge))
> 
> ret = panel_bridge_prepare_power(dsi->next_bridge);
> if (ret)
> 
> > +               DRM_INFO("can't prepare power the panel\n");
> 
> I think you should goto err_refcount;

Thanks for your review. I'll fix it next patch.

> 
> > +
> >         ret = clk_set_rate(dsi->hs_clk, dsi->data_rate);
> >         if (ret < 0) {
> >                 dev_err(dev, "Failed to set data rate: %d\n", ret);
> > -               goto err_refcount;
> > +               goto err_prepare_power;
> >         }
> >
> >         phy_power_on(dsi->phy);
> > @@ -661,7 +664,9 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
> >         clk_disable_unprepare(dsi->engine_clk);
> >  err_phy_power_off:
> >         phy_power_off(dsi->phy);
> > -err_refcount:
> > +err_prepare_power:
> > +       if (panel_bridge_unprepare_power(dsi->next_bridge))
> 
> ret = panel_bridge_unprepare_power(dsi->next_bridge);
> 
> > +               DRM_INFO("Can't unprepare power the panel\n");
> >         dsi->refcount--;
> >         return ret;
> >  }
> > @@ -694,6 +699,9 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
> >         clk_disable_unprepare(dsi->digital_clk);
> >
> >         phy_power_off(dsi->phy);
> > +
> > +       if (panel_bridge_unprepare_power(dsi->next_bridge))
> 
> ret = panel_bridge_unprepare_power(dsi->next_bridge);
> 
> > +               DRM_INFO("Can't unprepare power the panel\n");
> >  }
> >
> >  static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
> > --
> > 2.25.1
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