drm: renesas: shmobile: Turn vblank on/off when enabling/disabling CRTC

The DRM core vblank handling mechanism requires drivers to forcefully
turn vblank reporting off when disabling the CRTC, and to restore the
vblank reporting status when enabling the CRTC.
Implement this using the drm_crtc_vblank_{on,off}() helpers.

Note that drm_crtc_vblank_off() must be called at startup to synchronize
the state of the vblank core code with the hardware, which is initially
disabled.  This is performed at CRTC creation time, requiring vertical
blank initialization to be moved before creating CRTCs.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/e5833e5706b7792bfca8e6e56fc154a7c3e0574f.1694767209.git.geert+renesas@glider.be

diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
index 20adb9d2fa1782502487897ee0dbbe36e2e37d41..ab42a4999a55c475be6f760d7f2652d7f007485b 100644 (file)
--- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
+++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
@@ -271,6 +271,9 @@ static void shmob_drm_crtc_start(struct shmob_drm_crtc *scrtc)
 
        shmob_drm_crtc_start_stop(scrtc, true);
 
+       /* Turn vertical blank interrupt reporting back on. */
+       drm_crtc_vblank_on(crtc);
+
        scrtc->started = true;
 }
 
@@ -283,10 +286,12 @@ static void shmob_drm_crtc_stop(struct shmob_drm_crtc *scrtc)
                return;
 
        /*
-        * Wait for page flip completion before stopping the CRTC as userspace
+        * Disable vertical blank interrupt reporting.  We first need to wait
+        * for page flip completion before stopping the CRTC as userspace
         * expects page flips to eventually complete.
         */
        shmob_drm_crtc_wait_page_flip(scrtc);
+       drm_crtc_vblank_off(crtc);
 
        /* Stop the LCDC. */
        shmob_drm_crtc_start_stop(scrtc, false);
@@ -519,6 +524,9 @@ int shmob_drm_crtc_create(struct shmob_drm_device *sdev)
 
        drm_crtc_helper_add(crtc, &crtc_helper_funcs);
 
+       /* Start with vertical blank interrupt reporting disabled. */
+       drm_crtc_vblank_off(crtc);
+
        return 0;
 }
 

diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
index 2bd205f9ea7230625d5b1393703d7ca0d519cd67..c3a1995403d6c2c98c94a85eb538c1f5d77a4a83 100644 (file)
--- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
+++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
@@ -215,17 +215,17 @@ static int shmob_drm_probe(struct platform_device *pdev)
        if (ret)
                return ret;
 
-       ret = shmob_drm_modeset_init(sdev);
-       if (ret < 0)
-               return dev_err_probe(&pdev->dev, ret,
-                                    "failed to initialize mode setting\n");
-
        ret = drm_vblank_init(ddev, 1);
        if (ret < 0) {
                dev_err(&pdev->dev, "failed to initialize vblank\n");
-               goto err_modeset_cleanup;
+               return ret;
        }
 
+       ret = shmob_drm_modeset_init(sdev);
+       if (ret < 0)
+               return dev_err_probe(&pdev->dev, ret,
+                                    "failed to initialize mode setting\n");
+
        ret = platform_get_irq(pdev, 0);
        if (ret < 0)
                goto err_modeset_cleanup;