Commit b7243862 authored by Yannick Fertre's avatar Yannick Fertre Committed by Raphael Gallais-Pou
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drm/stm: ltdc: handle lvds pixel clock 



Handle LVDS pixel clock.

The LTDC operates with multiple clock domains for register access,
requiring all clocks to be provided during read/write operations.  This
imposes a dependency between the LVDS and LTDC to access correctly all
LTDC registers.  And because both IPs' pixel rates must be synchronized,
the LTDC has to handle the LVDS clock.

Signed-off-by: default avatarYannick Fertre <yannick.fertre@foss.st.com>
Acked-by: default avatarYannick Fertre <yannick.fertre@foss.st.com>
Acked-by: default avatarPhilippe Cornu <philippe.cornu@foss.st.com>
Link: https://lore.kernel.org/r/20250822-drm-misc-next-v5-8-9c825e28f733@foss.st.com


Signed-off-by: default avatarRaphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
parent d8066764

drivers/gpu/drm/stm/ltdc.c

+21 −1
Original line number Diff line number Diff line
@@ -838,6 +838,12 @@ ltdc_crtc_mode_valid(struct drm_crtc *crtc, 
	int target_max = target + CLK_TOLERANCE_HZ;

	int result;



	if (ldev->lvds_clk) {

		result = clk_round_rate(ldev->lvds_clk, target);

		drm_dbg_driver(crtc->dev, "lvds pixclk rate target %d, available %d\n",

			       target, result);

	}



	result = clk_round_rate(ldev->pixel_clk, target);



	drm_dbg_driver(crtc->dev, "clk rate target %d, available %d\n", target, result);
@@ -1879,6 +1885,8 @@ void ltdc_suspend(struct drm_device *ddev) 
	clk_disable_unprepare(ldev->pixel_clk);

	if (ldev->bus_clk)

		clk_disable_unprepare(ldev->bus_clk);

	if (ldev->lvds_clk)

		clk_disable_unprepare(ldev->lvds_clk);

}



int ltdc_resume(struct drm_device *ddev)
@@ -1896,8 +1904,16 @@ int ltdc_resume(struct drm_device *ddev) 


	if (ldev->bus_clk) {

		ret = clk_prepare_enable(ldev->bus_clk);

		if (ret)

		if (ret) {

			drm_err(ddev, "failed to enable bus clock (%d)\n", ret);

			return ret;

		}

	}



	if (ldev->lvds_clk) {

		ret = clk_prepare_enable(ldev->lvds_clk);

		if (ret)

			drm_err(ddev, "failed to prepare lvds clock\n");

	}



	return ret;
@@ -1982,6 +1998,10 @@ int ltdc_load(struct drm_device *ddev) 
		}

	}



	ldev->lvds_clk = devm_clk_get(dev, "lvds");

	if (IS_ERR(ldev->lvds_clk))

		ldev->lvds_clk = NULL;



	rstc = devm_reset_control_get_exclusive(dev, NULL);



	mutex_init(&ldev->err_lock);

drivers/gpu/drm/stm/ltdc.h

+1 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ struct ltdc_device { 
	void __iomem *regs;

	struct regmap *regmap;

	struct clk *pixel_clk;	/* lcd pixel clock */

	struct clk *lvds_clk;	/* lvds pixel clock */

	struct clk *bus_clk;	/* bus clock */

	struct mutex err_lock;	/* protecting error_status */

	struct ltdc_caps caps;