Re: [PATCH v13 13/14] drm/mediatek: dpi: Add dp_intf support

[AngeloGioacchino Del Regno]

Il 21/06/22 13:37, Bo-Chen Chen ha scritto:
> From: Guillaume Ranquet <granquet@xxxxxxxxxxxx>
>
> 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, we add a new config "round_pixels" to control setting of

Okay, I like where this is going, but "round_pixels" explains itself like
"the pixels are round" (which doesn't make sense).

So... is this "4 pixels per iteration" (computation of 4 pixels per iteration),
or "outputs 4 pixels at a time"?
I can give you some ideas about a better name for this struct member, I think...
...something like "output_4pixel"?

Alternatively, we can do something even cleaner here:
u8 pixels_per_round;

...where we define it like...

static const struct mtk_dpi_conf mt8195_dpintf_conf = {
	.pixels_per_round = 4,
	..........
}

static const struct mtk_dpi_conf mt8192_conf = {
	.pixels_per_round = 1,
	.........
}

... and then, in function mtk_dpi_set_display_mode(), we would have something like

	/*

	 * Depending on the IP version, we may output a different amount

	 * of pixels for each (choose: round/iteration): divide the clock

	 * by this number and adjust the display porches accordingly.

	 */

   	vm.pixelclock = pll_rate / factor;

	vm.pixelclock /= dpi->conf->pixels_per_round;



	......



   	hsync.sync_width = vm.hsync_len / dpi->conf->pixels_per_round;

   	hsync.back_porch = vm.hback_porch / dpi->conf->pixels_per_round;

   	hsync.front_porch = vm.hfront_porch / dpi->conf->pixels_per_round;

This would also eliminate any need to check if the IP has 4 pixels per round
or if it has just 1, as in the latter case, we'd be dividing by 1 (hence, we
would not be dividing anything).

Do you like this solution? :-)

Cheers,
Angelo

>     pixel clock and timing parameter for dp_intf.
>   - Input of dp_intf is two pixels per round, so we add a new config
>     "input_2pixel" to control this.
>   - 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@xxxxxxxxxxxx>.
>
> Signed-off-by: Markus Schneider-Pargmann <msp@xxxxxxxxxxxx>
> Signed-off-by: Guillaume Ranquet <granquet@xxxxxxxxxxxx>
> [Bo-Chen: Modify reviewers' comments.]
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@xxxxxxxxxxxx>
> ---
>   drivers/gpu/drm/mediatek/mtk_dpi.c          | 62 +++++++++++++++++++++
>   drivers/gpu/drm/mediatek/mtk_dpi_regs.h     | 12 ++++
>   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(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index ef7f828a4b1e..e562f0d55cc2 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -131,6 +131,11 @@ struct mtk_dpi_yc_limit {
>    * @color_fmt_trans_support: Enable color format transfer.
>    * @support_direct_pin: Dpi can directly connect pins, and enable this config
>    *			to do this.
> + * @round_pixels: Dp_intf is 4 pixels for one round while dpi is one pixel for
> + *		  one round, so we need to enable this config for dp_intf to do
> + *		  corresponding settings.
> + * @input_2pixel: Input pixel of dp_intf is 2 pixel per round, so enable this
> + *		  config to enable this feature.
>    * @dimension_mask: Mask used for HWIDTH, HPORCH, VSYNC_WIDTH and VSYNC_PORCH
>    *		    (no shift).
>    * @hvsize_mask: Mask of HSIZE and VSIZE mask (no shift).
> @@ -149,6 +154,8 @@ struct mtk_dpi_conf {
>   	bool swap_input_support;
>   	bool color_fmt_trans_support;
>   	bool support_direct_pin;
> +	bool round_pixels;
> +	bool input_2pixel;
>   	u32 dimension_mask;
>   	u32 hvsize_mask;
>   	u32 channel_swap_shift;
> @@ -560,6 +567,14 @@ 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->round_pixels)
> +		vm.pixelclock /= 4;
> +
>   	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);
> @@ -581,6 +596,17 @@ 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->round_pixels) {
> +		hsync.sync_width = vm.hsync_len / 4;
> +		hsync.back_porch = vm.hback_porch / 4;
> +		hsync.front_porch = vm.hfront_porch / 4;
> +	}
> +
>   	hsync.shift_half_line = false;
>   	vsync_lodd.sync_width = vm.vsync_len;
>   	vsync_lodd.back_porch = vm.vback_porch;
> @@ -629,6 +655,10 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>   		mtk_dpi_dual_edge(dpi);
>   		mtk_dpi_config_disable_edge(dpi);
>   	}
> +	if (dpi->conf->input_2pixel) {
> +		mtk_dpi_mask(dpi, DPI_CON, DPINTF_INPUT_2P_EN,
> +			     DPINTF_INPUT_2P_EN);
> +	}
>   	mtk_dpi_sw_reset(dpi, false);
>   
>   	return 0;
> @@ -869,6 +899,16 @@ static unsigned int mt8183_calculate_factor(int clock)
>   		return 2;
>   }
>   
> +static unsigned int mt8195_dpintf_calculate_factor(int clock)
> +{
> +	if (clock < 70000)
> +		return 4;
> +	else if (clock < 200000)
> +		return 2;
> +	else
> +		return 1;
> +}
> +
>   static const u32 mt8173_output_fmts[] = {
>   	MEDIA_BUS_FMT_RGB888_1X24,
>   };
> @@ -878,6 +918,11 @@ static const u32 mt8183_output_fmts[] = {
>   	MEDIA_BUS_FMT_RGB888_2X12_BE,
>   };
>   
> +static const u32 mt8195_output_fmts[] = {
> +	MEDIA_BUS_FMT_RGB888_1X24,
> +	MEDIA_BUS_FMT_YUYV8_1X16,
> +};
> +
>   static const struct mtk_dpi_conf mt8173_conf = {
>   	.cal_factor = mt8173_calculate_factor,
>   	.reg_h_fre_con = 0xe0,
> @@ -943,6 +988,20 @@ static const struct mtk_dpi_conf mt8192_conf = {
>   	.csc_enable_bit = CSC_ENABLE,
>   };
>   
> +static const struct mtk_dpi_conf mt8195_dpintf_conf = {
> +	.cal_factor = mt8195_dpintf_calculate_factor,
> +	.max_clock_khz = 600000,
> +	.output_fmts = mt8195_output_fmts,
> +	.num_output_fmts = ARRAY_SIZE(mt8195_output_fmts),
> +	.round_pixels = true,
> +	.input_2pixel = true,
> +	.dimension_mask = DPINTF_HPW_MASK,
> +	.hvsize_mask = DPINTF_HSIZE_MASK,
> +	.channel_swap_shift = DPINTF_CH_SWAP,
> +	.yuv422_en_bit = DPINTF_YUV422_EN,
> +	.csc_enable_bit = DPINTF_CSC_ENABLE,
> +};
> +
>   static int mtk_dpi_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -1065,6 +1124,9 @@ static const struct of_device_id mtk_dpi_of_ids[] = {
>   	{ .compatible = "mediatek,mt8192-dpi",
>   	  .data = &mt8192_conf,
>   	},
> +	{ .compatible = "mediatek,mt8195-dp-intf",
> +	  .data = &mt8195_dpintf_conf,
> +	},
>   	{ },
>   };
>   MODULE_DEVICE_TABLE(of, mtk_dpi_of_ids);