[PATCH 07/12] drm/stm: ltdc: handle lvds pixel clock

[Raphael Gallais-Pou]

From: Yannick Fertre <yannick.fer...@foss.st.com>

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: Yannick Fertre <yannick.fer...@foss.st.com>
Signed-off-by: Raphael Gallais-Pou <raphael.gallais-...@foss.st.com>
---
 drivers/gpu/drm/stm/ltdc.c | 22 +++++++++++++++++++++-
 drivers/gpu/drm/stm/ltdc.h |  1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index 
2bcdef76af2e8cbe3b6030deccefa097f28adc3a..031c561b8e780a55b77f4a4c8338e74b52bbbb48
 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -837,6 +837,12 @@ 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_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result);
@@ -1878,6 +1884,8 @@ 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)
@@ -1895,8 +1903,16 @@ 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;
@@ -1980,6 +1996,10 @@ 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);
diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
index 
ddfa8ae61a7ba5dc446fae647562d0ec8e6953e1..17b51a7ce28eee5de6d24ca943ca3b1f48695dfd
 100644
--- a/drivers/gpu/drm/stm/ltdc.h
+++ b/drivers/gpu/drm/stm/ltdc.h
@@ -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;

-- 
2.25.1