drm/exynos: fimd: clear channel before enabling iommu

If any fimd channel was already active, initializing iommu will result
in a PAGE FAULT (e.e. u-boot could have turned on the display and
not disabled it before the kernel starts). This patch checks if any
channel is active before initializing iommu and disables it.

Signed-off-by: Akshu Agrawal <akshu.a@samsung.com>
Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index 40fd6ccfcd6f7595671d750b57ea44066ddf4b87..99ae79e09e8251c97cfb961d45b3bc5c07ace8f7 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -143,6 +143,48 @@ static inline struct fimd_driver_data *drm_fimd_get_driver_data(
        return (struct fimd_driver_data *)of_id->data;
 }
 
+static void fimd_wait_for_vblank(struct exynos_drm_manager *mgr)
+{
+       struct fimd_context *ctx = mgr->ctx;
+
+       if (ctx->suspended)
+               return;
+
+       atomic_set(&ctx->wait_vsync_event, 1);
+
+       /*
+        * wait for FIMD to signal VSYNC interrupt or return after
+        * timeout which is set to 50ms (refresh rate of 20).
+        */
+       if (!wait_event_timeout(ctx->wait_vsync_queue,
+                               !atomic_read(&ctx->wait_vsync_event),
+                               HZ/20))
+               DRM_DEBUG_KMS("vblank wait timed out.\n");
+}
+
+
+static void fimd_clear_channel(struct exynos_drm_manager *mgr)
+{
+       struct fimd_context *ctx = mgr->ctx;
+       int win, ch_enabled = 0;
+
+       DRM_DEBUG_KMS("%s\n", __FILE__);
+
+       /* Check if any channel is enabled. */
+       for (win = 0; win < WINDOWS_NR; win++) {
+               u32 val = readl(ctx->regs + SHADOWCON);
+               if (val & SHADOWCON_CHx_ENABLE(win)) {
+                       val &= ~SHADOWCON_CHx_ENABLE(win);
+                       writel(val, ctx->regs + SHADOWCON);
+                       ch_enabled = 1;
+               }
+       }
+
+       /* Wait for vsync, as disable channel takes effect at next vsync */
+       if (ch_enabled)
+               fimd_wait_for_vblank(mgr);
+}
+
 static int fimd_mgr_initialize(struct exynos_drm_manager *mgr,
                        struct drm_device *drm_dev, int pipe)
 {
@@ -169,8 +211,14 @@ static int fimd_mgr_initialize(struct exynos_drm_manager *mgr,
        drm_dev->vblank_disable_allowed = true;
 
        /* attach this sub driver to iommu mapping if supported. */
-       if (is_drm_iommu_supported(ctx->drm_dev))
+       if (is_drm_iommu_supported(ctx->drm_dev)) {
+               /*
+                * If any channel is already active, iommu will throw
+                * a PAGE FAULT when enabled. So clear any channel if enabled.
+                */
+               fimd_clear_channel(mgr);
                drm_iommu_attach_device(ctx->drm_dev, ctx->dev);
+       }
 
        return 0;
 }
@@ -324,25 +372,6 @@ static void fimd_disable_vblank(struct exynos_drm_manager *mgr)
        }
 }
 
-static void fimd_wait_for_vblank(struct exynos_drm_manager *mgr)
-{
-       struct fimd_context *ctx = mgr->ctx;
-
-       if (ctx->suspended)
-               return;
-
-       atomic_set(&ctx->wait_vsync_event, 1);
-
-       /*
-        * wait for FIMD to signal VSYNC interrupt or return after
-        * timeout which is set to 50ms (refresh rate of 20).
-        */
-       if (!wait_event_timeout(ctx->wait_vsync_queue,
-                               !atomic_read(&ctx->wait_vsync_event),
-                               HZ/20))
-               DRM_DEBUG_KMS("vblank wait timed out.\n");
-}
-
 static void fimd_win_mode_set(struct exynos_drm_manager *mgr,
                        struct exynos_drm_overlay *overlay)
 {