Re: [PATCH v8 13/19] drm/mediatek: dpi: Add dpintf support

[Maxime Ripard <maxime@cerno.tech>]

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Hi

(Now I remember your series ;)

On Fri, Feb 18, 2022 at 03:54:31PM +0100, Guillaume Ranquet wrote:
> 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:
>  - Some features/functional components are not available for dpintf
>    which are now excluded from code execution once is_dpintf is set
>  - dpintf can and needs to choose between different clockdividers based
>    on the clockspeed. This is done by choosing a different clock parent.
>  - There are two additional clocks that need to be managed. These are
>    only set for dpintf and will be set to NULL if not supplied. The
>    clk_* calls handle these as normal clocks then.
>  - 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
> Jason-JH.Lin <jason-jh.lin@mediatek.com>.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c          | 164 +++++++++++++++++---
>  drivers/gpu/drm/mediatek/mtk_dpi_regs.h     |  38 +++++
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c |   8 +
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |   1 +
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c      |   5 +-
>  include/linux/soc/mediatek/mtk-mmsys.h      |   2 +
>  6 files changed, 198 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index be99399faf1bb..c5639ada868f8 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -63,6 +63,14 @@ enum mtk_dpi_out_color_format {
>  	MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL
>  };
>  
> +enum TVDPLL_CLK {
> +	TVDPLL_PLL = 0,
> +	TVDPLL_D2 = 2,
> +	TVDPLL_D4 = 4,
> +	TVDPLL_D8 = 8,
> +	TVDPLL_D16 = 16,
> +};
> +
>  struct mtk_dpi {
>  	struct drm_encoder encoder;
>  	struct drm_bridge bridge;
> @@ -71,8 +79,10 @@ struct mtk_dpi {
>  	void __iomem *regs;
>  	struct device *dev;
>  	struct clk *engine_clk;
> +	struct clk *dpi_ck_cg;
>  	struct clk *pixel_clk;
>  	struct clk *tvd_clk;
> +	struct clk *pclk_src[5];
>  	int irq;
>  	struct drm_display_mode mode;
>  	const struct mtk_dpi_conf *conf;
> @@ -126,6 +136,7 @@ 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;
> @@ -384,6 +395,25 @@ 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_matrix_sel(struct mtk_dpi *dpi, enum mtk_dpi_out_color_format format)
> +{
> +	u32 matrix_sel = 0;
> +
> +	switch (format) {
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_422:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_444:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_444_FULL:
> +	case MTK_DPI_COLOR_FORMAT_XV_YCC:
> +		if (dpi->mode.hdisplay <= 720)
> +			matrix_sel = 0x2;
> +		break;
> +	default:
> +		break;
> +	}
> +	mtk_dpi_mask(dpi, DPI_MATRIX_SET, matrix_sel, INT_MATRIX_SEL_MASK);
> +}
> +
>  static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  					enum mtk_dpi_out_color_format format)
>  {
> @@ -391,6 +421,7 @@ static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  	    (format == MTK_DPI_COLOR_FORMAT_YCBCR_444_FULL)) {
>  		mtk_dpi_config_yuv422_enable(dpi, false);
>  		mtk_dpi_config_csc_enable(dpi, true);
> +		mtk_dpi_matrix_sel(dpi, format);
>  		if (dpi->conf->swap_input_support)
>  			mtk_dpi_config_swap_input(dpi, false);
>  		mtk_dpi_config_channel_swap(dpi, MTK_DPI_OUT_CHANNEL_SWAP_BGR);
> @@ -398,6 +429,7 @@ static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  		   (format == MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL)) {
>  		mtk_dpi_config_yuv422_enable(dpi, true);
>  		mtk_dpi_config_csc_enable(dpi, true);
> +		mtk_dpi_matrix_sel(dpi, format);
>  		if (dpi->conf->swap_input_support)
>  			mtk_dpi_config_swap_input(dpi, true);
>  		mtk_dpi_config_channel_swap(dpi, MTK_DPI_OUT_CHANNEL_SWAP_RGB);
> @@ -438,6 +470,8 @@ static void mtk_dpi_power_off(struct mtk_dpi *dpi)
>  	mtk_dpi_disable(dpi);
>  	clk_disable_unprepare(dpi->pixel_clk);
>  	clk_disable_unprepare(dpi->engine_clk);
> +	clk_disable_unprepare(dpi->dpi_ck_cg);
> +	clk_disable_unprepare(dpi->tvd_clk);
>  }
>  
>  static int mtk_dpi_power_on(struct mtk_dpi *dpi)
> @@ -447,12 +481,24 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>  	if (++dpi->refcount != 1)
>  		return 0;
>  
> +	ret = clk_prepare_enable(dpi->tvd_clk);
> +	if (ret) {
> +		dev_err(dpi->dev, "Failed to enable tvd pll: %d\n", ret);
> +		goto err_pixel;
> +	}
> +
>  	ret = clk_prepare_enable(dpi->engine_clk);
>  	if (ret) {
>  		dev_err(dpi->dev, "Failed to enable engine clock: %d\n", ret);
>  		goto err_refcount;
>  	}
>  
> +	ret = clk_prepare_enable(dpi->dpi_ck_cg);
> +	if (ret) {
> +		dev_err(dpi->dev, "Failed to enable dpi_ck_cg clock: %d\n", ret);
> +		goto err_ck_cg;
> +	}
> +
>  	ret = clk_prepare_enable(dpi->pixel_clk);
>  	if (ret) {
>  		dev_err(dpi->dev, "Failed to enable pixel clock: %d\n", ret);
> @@ -462,10 +508,11 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>  	if (dpi->pinctrl && dpi->pins_dpi)
>  		pinctrl_select_state(dpi->pinctrl, dpi->pins_dpi);
>  
> -	mtk_dpi_enable(dpi);
>  	return 0;
>  
>  err_pixel:
> +	clk_disable_unprepare(dpi->dpi_ck_cg);
> +err_ck_cg:
>  	clk_disable_unprepare(dpi->engine_clk);
>  err_refcount:
>  	dpi->refcount--;
> @@ -497,12 +544,21 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  	pll_rate = clk_get_rate(dpi->tvd_clk);
>  
>  	vm.pixelclock = pll_rate / factor;
> -	if ((dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_LE) ||
> -	    (dpi->output_fmt == MEDIA_BUS_FMT_RGB888_2X12_BE))
> +	if (dpi->conf->is_dpintf) {
> +		if (factor == 1)
> +			clk_set_parent(dpi->pixel_clk, dpi->pclk_src[2]);
> +		else if (factor == 2)
> +			clk_set_parent(dpi->pixel_clk, dpi->pclk_src[3]);
> +		else if (factor == 4)
> +			clk_set_parent(dpi->pixel_clk, dpi->pclk_src[4]);
> +		else
> +			clk_set_parent(dpi->pixel_clk, dpi->pclk_src[2]);

You get a reference to these clocks using:
>
> +	dpi->pclk_src[1] = devm_clk_get(dev, "TVDPLL_D2");
> +	dpi->pclk_src[2] = devm_clk_get(dev, "TVDPLL_D4");
> +	dpi->pclk_src[3] = devm_clk_get(dev, "TVDPLL_D8");
> +	dpi->pclk_src[4] = devm_clk_get(dev, "TVDPLL_D16");
> +

So if the clock isn't there, you'll get an error pointer, won't check
it, but will dereference it.

If the clock is optional, you should use clk_get_optional, otherwise you
should check the error returned.

That clock setup is weird though. I don't have any knowledge about your
platform, but either the clock should be a single one if it has multiple
dividers, or the pixel_clk clock should behave as a mux and just pick
the best parent for the rate it's given.

Maxime

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