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SubjectRe: [PATCH v13 5/6] drm/mediatek: dpi sample mode support
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On 11/03/2020 08:18, 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@mediatek.com>
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_dpi.c | 27 +++++++++++++++++++++++++--
> 1 file changed, 25 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 087f5ce732e1..2871e68e7767 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;
> @@ -693,6 +705,7 @@ static const struct mtk_dpi_conf mt8183_conf = {
> static int mtk_dpi_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> + struct device_node *ep;
> struct mtk_dpi *dpi;
> struct resource *mem;
> int comp_id;
> @@ -705,6 +718,16 @@ static int mtk_dpi_probe(struct platform_device *pdev)
> dpi->dev = dev;
> dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);
>
> + ep = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
> + if (!ep) {
> + dev_err(dev, "Failed get the endpoint port\n");
> + return -EINVAL;
> + }
> +
> + /* Get the sampling edge from the endpoint. */
> + of_property_read_u32(ep, "pclk-sample", &dpi->pclk_sample);
> + of_node_put(ep);

Instead of having hard-coded value in DT, you should switch to bridge bus
format negotiation instead.

Boris pushed support a few weeks ago and the dw-hdmi bridge has been updated
to work with it and negotiate the format between the encoder and the bridge.

Phong is pushing the it66121 bridge driver which is used on a MT8183 board, and
should make use of that to handle the dual edge support between the 8183 dpi and
the it66121 bridge.

Neil

> +
> mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> dpi->regs = devm_ioremap_resource(dev, mem);
> if (IS_ERR(dpi->regs)) {
>

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