Re: [PATCH v13 5/6] drm/mediatek: dpi sample mode support

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)) {