linux-kernel - Re: [PATCH v8 5/7] drm/mediatek: dpi sample mode support

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Date:   Wed, 26 Feb 2020 10:08:53 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Jitao Shi <jitao.shi@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <yingjoe.chen@...iatek.com>,
        <eddie.huang@...iatek.com>, <cawa.cheng@...iatek.com>,
        <bibby.hsieh@...iatek.com>, <stonea168@....com>,
        <huijuan.xie@...iatek.com>
Subject: Re: [PATCH v8 5/7] drm/mediatek: dpi sample mode support

On Tue, 2020-02-25 at 17:40 +0800, Jitao Shi 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.
> 

Reviewed-by: CK Hu <ck.hu@...iatek.com>

> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 01fa8b8d763d..df598f87a40f 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -75,6 +75,7 @@ struct mtk_dpi {
>  	enum mtk_dpi_out_bit_num bit_num;
>  	enum mtk_dpi_out_channel_swap channel_swap;
>  	int refcount;
> +	u32 pclk_sample;
>  };
>  
>  static inline struct mtk_dpi *mtk_dpi_from_encoder(struct drm_encoder *e)
> @@ -348,6 +349,13 @@ static void mtk_dpi_config_disable_edge(struct mtk_dpi *dpi)
>  		mtk_dpi_mask(dpi, dpi->conf->reg_h_fre_con, 0, EDGE_SEL_EN);
>  }
>  
> +static void mtk_dpi_enable_pclk_sample_dual_edge(struct mtk_dpi *dpi)
> +{
> +	mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN | DDR_4PHASE,
> +		     DDR_EN | DDR_4PHASE);
> +	mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING, EDGE_SEL, EDGE_SEL);
> +}
> +
>  static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  					enum mtk_dpi_out_color_format format)
>  {
> @@ -439,7 +447,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  	pll_rate = clk_get_rate(dpi->tvd_clk);
>  
>  	vm.pixelclock = pll_rate / factor;
> -	clk_set_rate(dpi->pixel_clk, vm.pixelclock);
> +	clk_set_rate(dpi->pixel_clk,
> +		     vm.pixelclock * (dpi->pclk_sample > 1 ? 2 : 1));
>  	vm.pixelclock = clk_get_rate(dpi->pixel_clk);
>  
>  	dev_dbg(dpi->dev, "Got  PLL %lu Hz, pixel clock %lu Hz\n",
> @@ -450,7 +459,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  	limit.y_bottom = 0x0010;
>  	limit.y_top = 0x0FE0;
>  
> -	dpi_pol.ck_pol = MTK_DPI_POLARITY_FALLING;
> +	dpi_pol.ck_pol = dpi->pclk_sample == 1 ?
> +			 MTK_DPI_POLARITY_RISING : MTK_DPI_POLARITY_FALLING;
>  	dpi_pol.de_pol = MTK_DPI_POLARITY_RISING;
>  	dpi_pol.hsync_pol = vm.flags & DISPLAY_FLAGS_HSYNC_HIGH ?
>  			    MTK_DPI_POLARITY_FALLING : MTK_DPI_POLARITY_RISING;
> @@ -504,6 +514,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  	mtk_dpi_config_color_format(dpi, dpi->color_format);
>  	mtk_dpi_config_2n_h_fre(dpi);
>  	mtk_dpi_config_disable_edge(dpi);
> +	if (dpi->pclk_sample > 1)
> +		mtk_dpi_enable_pclk_sample_dual_edge(dpi);
>  	mtk_dpi_sw_reset(dpi, false);
>  
>  	return 0;
> @@ -689,6 +701,8 @@ static int mtk_dpi_probe(struct platform_device *pdev)
>  
>  	dpi->dev = dev;
>  	dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);
> +	of_property_read_u32_index(dev->of_node, "pclk-sample", 1,
> +				   &dpi->pclk_sample);
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	dpi->regs = devm_ioremap_resource(dev, mem);