linux-kernel - Re: [v2,PATCH 1/3] drm/mediatek: dpi dual edge sample mode support

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Date:   Thu, 29 Apr 2021 10:23:46 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     Neil Armstrong <narmstrong@...libre.com>,
        <chunkuang.hu@...nel.org>, <matthias.bgg@...il.com>
CC:     <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        Jitao Shi <jitao.shi@...iatek.com>
Subject: Re: [v2,PATCH 1/3] drm/mediatek: dpi dual edge sample mode support

On Mon, 2021-04-19 at 09:36 +0200, Neil Armstrong wrote:
> Hi,
> 
> On 14/04/2021 15:35, Rex-BC Chen wrote:
> > DPI can sample on falling, rising or both edge.
> > When DPI sample the data both rising and falling edge.
> > It can reduce half data io pins.
> > 
> > Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> > Signed-off-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dpi.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > index b05f900d9322..21a3a7b78835 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > @@ -83,6 +83,7 @@ struct mtk_dpi {
> >  	struct pinctrl *pinctrl;
> >  	struct pinctrl_state *pins_gpio;
> >  	struct pinctrl_state *pins_dpi;
> > +	bool ddr_edge_sel;
> >  	int refcount;
> >  };
> >  
> > @@ -121,6 +122,7 @@ struct mtk_dpi_conf {
> >  	unsigned int (*cal_factor)(int clock);
> >  	u32 reg_h_fre_con;
> >  	bool edge_sel_en;
> > +	bool dual_edge;
> >  };
> >  
> >  static void mtk_dpi_mask(struct mtk_dpi *dpi, u32 offset, u32 val,
> > u32 mask)
> > @@ -380,6 +382,15 @@ static void mtk_dpi_config_color_format(struct
> > mtk_dpi *dpi,
> >  	}
> >  }
> >  
> > +static void mtk_dpi_dual_edge(struct mtk_dpi *dpi)
> > +{
> > +	if (dpi->conf->dual_edge) {
> > +		mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN | DDR_4PHASE,
> > +			     DDR_EN | DDR_4PHASE);
> > +		mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING, dpi->ddr_edge_sel 
> > ? EDGE_SEL : 0, EDGE_SEL);
> > +	}
> > +}
> > +
> 
> By using the downstream code as reference:
> 
> -       clk_set_rate(dpi->pixel_clk, vm.pixelclock);
> +       clk_set_rate(dpi->pixel_clk, vm.pixelclock * (dpi->conf-
> >dual_edge ? 2 : 1));
> 
> is missing in mtk_dpi_set_display_mode()
> 
Hello Neil,

Thanks for helping checking this.
I will add this modification for next patch.

BRs,
Rex-BC Chen
> >  static void mtk_dpi_power_off(struct mtk_dpi *dpi)
> >  {
> >  	if (WARN_ON(dpi->refcount == 0))
> > @@ -518,6 +529,7 @@ static int mtk_dpi_set_display_mode(struct
> > mtk_dpi *dpi,
> >  	mtk_dpi_config_yc_map(dpi, dpi->yc_map);
> >  	mtk_dpi_config_color_format(dpi, dpi->color_format);
> >  	mtk_dpi_config_2n_h_fre(dpi);
> > +	mtk_dpi_dual_edge(dpi);
> >  	mtk_dpi_config_disable_edge(dpi);
> >  	mtk_dpi_sw_reset(dpi, false);
> >  
> > 
> 
> Neil