linux-kernel - Re: [PATCH v12 10/14] drm/mediatek: dpi: Add dpintf support

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Date:   Tue, 21 Jun 2022 10:32:30 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Bo-Chen Chen <rex-bc.chen@...iatek.com>, <chunkuang.hu@...nel.org>,
        <p.zabel@...gutronix.de>, <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <matthias.bgg@...il.com>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <angelogioacchino.delregno@...labora.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v12 10/14] drm/mediatek: dpi: Add dpintf support

Hi, Bo-Chen:

On Mon, 2022-06-20 at 20:10 +0800, Bo-Chen Chen wrote:
> From: Guillaume Ranquet <granquet@...libre.com>
> 
> dpintf is the displayport interface hardware unit. This unit is
> similar
> to dpi and can reuse most of the code.
> 
> This patch adds support for mt8195-dpintf to this dpi driver. Main
> differences are:
>  - 4 pixels for one round for dp_intf while dpi is 1 pixel for one
> round.
>    Therefore, pixel clock and timing parameter should be divided by 4
> for
>    dp_intf.
>  - Some features/functional components are not available for dpintf
>    which are now excluded from code execution once is_dpintf is set.
>    The main difference is some parts of hardware design between
> dp_intf
>    and dpi.
>  - Some register contents differ slightly between the two components.
> To
>    work around this I added register bits/masks with a DPINTF_ prefix
>    and use them where different.
> 
> Based on a separate driver for dpintf created by
> Jitao shi <jitao.shi@...iatek.com>.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> [Bo-Chen: Modify reviewers' comments.]
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c          | 65
> +++++++++++++++++++--
>  drivers/gpu/drm/mediatek/mtk_dpi_regs.h     | 13 +++++
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c |  4 ++
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |  1 +
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c      |  3 +
>  5 files changed, 82 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index e186870ba3bc..2717b1741b7a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -126,6 +126,7 @@ struct mtk_dpi_conf {
>  	const u32 *output_fmts;
>  	u32 num_output_fmts;
>  	bool is_ck_de_pol;
> +	bool is_dpintf;
>  	bool swap_input_support;
>  	/* Mask used for HWIDTH, HPORCH, VSYNC_WIDTH and VSYNC_PORCH
> (no shift) */
>  	u32 dimension_mask;
> @@ -513,6 +514,14 @@ static int mtk_dpi_set_display_mode(struct
> mtk_dpi *dpi,
>  	pll_rate = clk_get_rate(dpi->tvd_clk);
>  
>  	vm.pixelclock = pll_rate / factor;
> +
> +	/*
> +	 * For dp_intf, we need to divide clock by 4 because it's
> +	 * 4 pixels for one round while dpi is 1 pixel for one round.
> +	 */
> +	if (dpi->conf->is_dpintf)
> +		vm.pixelclock /= 4;

I this this should define dpi->conf->round_pixels rather than dpi-
>conf->is_dpintf.

> +
>  	if ((dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_LE) ||
>  	    (dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_BE))
>  		clk_set_rate(dpi->pixel_clk, vm.pixelclock * 2);
> @@ -534,6 +543,17 @@ static int mtk_dpi_set_display_mode(struct
> mtk_dpi *dpi,
>  	hsync.sync_width = vm.hsync_len;
>  	hsync.back_porch = vm.hback_porch;
>  	hsync.front_porch = vm.hfront_porch;
> +
> +	/*
> +	 * For dp_intf, we need to divide everything by 4 because it's
> +	 * 4 pixels for one round while dpi is 1 pixel for one round.
> +	 */
> +	if (dpi->conf->is_dpintf) {
> +		hsync.sync_width = vm.hsync_len / 4;
> +		hsync.back_porch = vm.hback_porch / 4;
> +		hsync.front_porch = vm.hfront_porch / 4;
> +	}

Ditto.

> +
>  	hsync.shift_half_line = false;
>  	vsync_lodd.sync_width = vm.vsync_len;
>  	vsync_lodd.back_porch = vm.vback_porch;
> @@ -575,11 +595,16 @@ static int mtk_dpi_set_display_mode(struct
> mtk_dpi *dpi,
>  	mtk_dpi_config_channel_limit(dpi);
>  	mtk_dpi_config_bit_num(dpi, dpi->bit_num);
>  	mtk_dpi_config_channel_swap(dpi, dpi->channel_swap);
> -	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);
> +	if (dpi->conf->is_dpintf) {

Separate this to an independent patch and give a better config name
rather than dpi->conf->is_dpintf.

> +		mtk_dpi_mask(dpi, DPI_CON, DPINTF_INPUT_2P_EN,
> +			     DPINTF_INPUT_2P_EN);
> +	} else {
> +		mtk_dpi_config_yc_map(dpi, dpi->yc_map);
> +		mtk_dpi_config_2n_h_fre(dpi);
> +		mtk_dpi_dual_edge(dpi);
> +		mtk_dpi_config_disable_edge(dpi);
> +	}
>  	mtk_dpi_sw_reset(dpi, false);
>  
>  	return 0;
> @@ -817,6 +842,16 @@ static unsigned int mt8183_calculate_factor(int
> clock)
>  		return 2;
>  }
>  

[snip]

>  
>  #define EDGE_SEL_EN			BIT(5)
>  #define H_FRE_2N			BIT(25)
> +

This seems not related to dpintf support.

Regards,
CK

>  #endif /* __MTK_DPI_REGS_H */
>