Commit 86c1b9ef authored by Eric Anholt's avatar Eric Anholt
Browse files

drm/vc4: Adjust modes in DSI to work around the integer PLL divider. 



BCM2835's PLLD_DSI1 divider doesn't give us many choices for our pixel
clocks, so to support panels on the Raspberry Pi we need to set a
higher pixel clock rate than requested and adjust the mode we program
to extend out the HFP so that the refresh rate matches.

v2: Drop an unfinished comment (caught by Noralf)

Signed-off-by: default avatarEric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511235625.22427-2-eric@anholt.net


Acked-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent fdb888de

drivers/gpu/drm/vc4/vc4_dsi.c

+86 −26
Original line number Diff line number Diff line
@@ -519,7 +519,8 @@ struct vc4_dsi { 
	/* DSI channel for the panel we're connected to. */

	u32 channel;

	u32 lanes;

	enum mipi_dsi_pixel_format format;

	u32 format;

	u32 divider;

	u32 mode_flags;



	/* Input clock from CPRMAN to the digital PHY, for the DSI
@@ -906,13 +907,67 @@ static void vc4_dsi_encoder_disable(struct drm_encoder *encoder) 
	pm_runtime_put(dev);

}



/* Extends the mode's blank intervals to handle BCM2835's integer-only

 * DSI PLL divider.

 *

 * On 2835, PLLD is set to 2Ghz, and may not be changed by the display

 * driver since most peripherals are hanging off of the PLLD_PER

 * divider.  PLLD_DSI1, which drives our DSI bit clock (and therefore

 * the pixel clock), only has an integer divider off of DSI.

 *

 * To get our panel mode to refresh at the expected 60Hz, we need to

 * extend the horizontal blank time.  This means we drive a

 * higher-than-expected clock rate to the panel, but that's what the

 * firmware does too.

 */

static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder,

				       const struct drm_display_mode *mode,

				       struct drm_display_mode *adjusted_mode)

{

	struct vc4_dsi_encoder *vc4_encoder = to_vc4_dsi_encoder(encoder);

	struct vc4_dsi *dsi = vc4_encoder->dsi;

	struct clk *phy_parent = clk_get_parent(dsi->pll_phy_clock);

	unsigned long parent_rate = clk_get_rate(phy_parent);

	unsigned long pixel_clock_hz = mode->clock * 1000;

	unsigned long pll_clock = pixel_clock_hz * dsi->divider;

	int divider;



	/* Find what divider gets us a faster clock than the requested

	 * pixel clock.

	 */

	for (divider = 1; divider < 8; divider++) {

		if (parent_rate / divider < pll_clock) {

			divider--;

			break;

		}

	}



	/* Now that we've picked a PLL divider, calculate back to its

	 * pixel clock.

	 */

	pll_clock = parent_rate / divider;

	pixel_clock_hz = pll_clock / dsi->divider;



	/* Round up the clk_set_rate() request slightly, since

	 * PLLD_DSI1 is an integer divider and its rate selection will

	 * never round up.

	 */

	adjusted_mode->clock = pixel_clock_hz / 1000 + 1;



	/* Given the new pixel clock, adjust HFP to keep vrefresh the same. */

	adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal);

	adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal;

	adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal;



	return true;

}



static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)

{

	struct drm_display_mode *mode = &encoder->crtc->mode;

	struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode;

	struct vc4_dsi_encoder *vc4_encoder = to_vc4_dsi_encoder(encoder);

	struct vc4_dsi *dsi = vc4_encoder->dsi;

	struct device *dev = &dsi->pdev->dev;

	u32 format = 0, divider = 0;

	bool debug_dump_regs = false;

	unsigned long hs_clock;

	u32 ui_ns;
@@ -940,26 +995,7 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder) 
		vc4_dsi_dump_regs(dsi);

	}



	switch (dsi->format) {

	case MIPI_DSI_FMT_RGB888:

		format = DSI_PFORMAT_RGB888;

		divider = 24 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB666:

		format = DSI_PFORMAT_RGB666;

		divider = 24 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB666_PACKED:

		format = DSI_PFORMAT_RGB666_PACKED;

		divider = 18 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB565:

		format = DSI_PFORMAT_RGB565;

		divider = 16 / dsi->lanes;

		break;

	}



	phy_clock = pixel_clock_hz * divider;

	phy_clock = pixel_clock_hz * dsi->divider;

	ret = clk_set_rate(dsi->pll_phy_clock, phy_clock);

	if (ret) {

		dev_err(&dsi->pdev->dev,
@@ -1134,8 +1170,9 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder) 


	if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO) {

		DSI_PORT_WRITE(DISP0_CTRL,

			       VC4_SET_FIELD(divider, DSI_DISP0_PIX_CLK_DIV) |

			       VC4_SET_FIELD(format, DSI_DISP0_PFORMAT) |

			       VC4_SET_FIELD(dsi->divider,

					     DSI_DISP0_PIX_CLK_DIV) |

			       VC4_SET_FIELD(dsi->format, DSI_DISP0_PFORMAT) |

			       VC4_SET_FIELD(DSI_DISP0_LP_STOP_PERFRAME,

					     DSI_DISP0_LP_STOP_CTRL) |

			       DSI_DISP0_ST_END |
@@ -1347,9 +1384,31 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host, 


	dsi->lanes = device->lanes;

	dsi->channel = device->channel;

	dsi->format = device->format;

	dsi->mode_flags = device->mode_flags;



	switch (device->format) {

	case MIPI_DSI_FMT_RGB888:

		dsi->format = DSI_PFORMAT_RGB888;

		dsi->divider = 24 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB666:

		dsi->format = DSI_PFORMAT_RGB666;

		dsi->divider = 24 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB666_PACKED:

		dsi->format = DSI_PFORMAT_RGB666_PACKED;

		dsi->divider = 18 / dsi->lanes;

		break;

	case MIPI_DSI_FMT_RGB565:

		dsi->format = DSI_PFORMAT_RGB565;

		dsi->divider = 16 / dsi->lanes;

		break;

	default:

		dev_err(&dsi->pdev->dev, "Unknown DSI format: %d.\n",

			dsi->format);

		return 0;

	}



	if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO)) {

		dev_err(&dsi->pdev->dev,

			"Only VIDEO mode panels supported currently.\n");
@@ -1397,6 +1456,7 @@ static const struct mipi_dsi_host_ops vc4_dsi_host_ops = { 
static const struct drm_encoder_helper_funcs vc4_dsi_encoder_helper_funcs = {

	.disable = vc4_dsi_encoder_disable,

	.enable = vc4_dsi_encoder_enable,

	.mode_fixup = vc4_dsi_encoder_mode_fixup,

};



static const struct of_device_id vc4_dsi_dt_match[] = {

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