drm/exynos: Fix cleanup of IOMMU related objects

Store the IOMMU mapping created by the device core of each Exynos DRM
sub-device and restore it when the Exynos DRM driver is unbound. This
fixes IOMMU initialization failure for the second time when a deferred
probe is triggered from the bind() callback of master's compound DRM
driver. This also fixes the following issue found using kmemleak
detector:

unreferenced object 0xc2137640 (size 64):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    50 a3 14 c2 80 a2 14 c2 01 00 00 00 20 00 00 00  P........... ...
    00 10 00 00 00 80 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xc214a280 (size 128):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 a0 ec ed 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xedeca000 (size 4096):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20
    [<8cd12507>] 0x0
unreferenced object 0xc214a300 (size 128):
  comm "swapper/0", pid 1, jiffies 4294937900 (age 3127.400s)
  hex dump (first 32 bytes):
    00 a3 14 c2 00 a3 14 c2 00 40 18 c2 00 80 18 c2  .........@......
    02 00 02 00 ad 4e ad de ff ff ff ff ff ff ff ff  .....N..........
  backtrace:
    [<08cbd8bc>] iommu_domain_alloc+0x24/0x50
    [<b835abee>] arm_iommu_create_mapping+0xe4/0x134
    [<3acd268d>] arch_setup_dma_ops+0x4c/0x104
    [<9f7d2cce>] of_dma_configure+0x19c/0x3a4
    [<ba07704b>] really_probe+0xb0/0x47c
    [<4f510e4f>] driver_probe_device+0x78/0x1c4
    [<7481a0cf>] device_driver_attach+0x58/0x60
    [<0ff8f5c1>] __driver_attach+0xb8/0x158
    [<86006144>] bus_for_each_dev+0x74/0xb4
    [<10159dca>] bus_add_driver+0x1c0/0x200
    [<8a265265>] driver_register+0x74/0x108
    [<e0f3451a>] exynos_drm_init+0xb0/0x134
    [<db3fc7ba>] do_one_initcall+0x90/0x458
    [<6da35917>] kernel_init_freeable+0x188/0x200
    [<db3f74d4>] kernel_init+0x8/0x110
    [<1f3cddf9>] ret_from_fork+0x14/0x20

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

diff --git a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
index 8428ae1..1f79bc2 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos5433_drm_decon.c
@@ -55,6 +55,7 @@ static const char * const decon_clks_name[] = {
 struct decon_context {
        struct device                   *dev;
        struct drm_device               *drm_dev;
+       void                            *dma_priv;
        struct exynos_drm_crtc          *crtc;
        struct exynos_drm_plane         planes[WINDOWS_NR];
        struct exynos_drm_plane_config  configs[WINDOWS_NR];
@@ -644,7 +645,7 @@ static int decon_bind(struct device *dev, struct device *master, void *data)
 
        decon_clear_channels(ctx->crtc);
 
-       return exynos_drm_register_dma(drm_dev, dev);
+       return exynos_drm_register_dma(drm_dev, dev, &ctx->dma_priv);
 }
 
 static void decon_unbind(struct device *dev, struct device *master, void *data)
@@ -654,7 +655,7 @@ static void decon_unbind(struct device *dev, struct device *master, void *data)
        decon_atomic_disable(ctx->crtc);
 
        /* detach this sub driver from iommu mapping if supported. */
-       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev);
+       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev, &ctx->dma_priv);
 }
 
 static const struct component_ops decon_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos7_drm_decon.c b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
index ff59c64..1eed332 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos7_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
@@ -40,6 +40,7 @@
 struct decon_context {
        struct device                   *dev;
        struct drm_device               *drm_dev;
+       void                            *dma_priv;
        struct exynos_drm_crtc          *crtc;
        struct exynos_drm_plane         planes[WINDOWS_NR];
        struct exynos_drm_plane_config  configs[WINDOWS_NR];
@@ -127,13 +128,13 @@ static int decon_ctx_initialize(struct decon_context *ctx,
 
        decon_clear_channels(ctx->crtc);
 
-       return exynos_drm_register_dma(drm_dev, ctx->dev);
+       return exynos_drm_register_dma(drm_dev, ctx->dev, &ctx->dma_priv);
 }
 
 static void decon_ctx_remove(struct decon_context *ctx)
 {
        /* detach this sub driver from iommu mapping if supported. */
-       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev);
+       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev, &ctx->dma_priv);
 }
 
 static u32 decon_calc_clkdiv(struct decon_context *ctx,

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dma.c b/drivers/gpu/drm/exynos/exynos_drm_dma.c
index 9ebc027..619f814 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_dma.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dma.c
@@ -58,7 +58,7 @@ static inline void clear_dma_max_seg_size(struct device *dev)
  * mapping.
  */
 static int drm_iommu_attach_device(struct drm_device *drm_dev,
-                               struct device *subdrv_dev)
+                               struct device *subdrv_dev, void **dma_priv)
 {
        struct exynos_drm_private *priv = drm_dev->dev_private;
        int ret;
@@ -74,7 +74,14 @@ static int drm_iommu_attach_device(struct drm_device *drm_dev,
                return ret;
 
        if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
-               if (to_dma_iommu_mapping(subdrv_dev))
+               /*
+                * Keep the original DMA mapping of the sub-device and
+                * restore it on Exynos DRM detach, otherwise the DMA
+                * framework considers it as IOMMU-less during the next
+                * probe (in case of deferred probe or modular build)
+                */
+               *dma_priv = to_dma_iommu_mapping(subdrv_dev);
+               if (*dma_priv)
                        arm_iommu_detach_device(subdrv_dev);
 
                ret = arm_iommu_attach_device(subdrv_dev, priv->mapping);
@@ -98,19 +105,21 @@ static int drm_iommu_attach_device(struct drm_device *drm_dev,
  * mapping
  */
 static void drm_iommu_detach_device(struct drm_device *drm_dev,
-                               struct device *subdrv_dev)
+                                   struct device *subdrv_dev, void **dma_priv)
 {
        struct exynos_drm_private *priv = drm_dev->dev_private;
 
-       if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
+       if (IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)) {
                arm_iommu_detach_device(subdrv_dev);
-       else if (IS_ENABLED(CONFIG_IOMMU_DMA))
+               arm_iommu_attach_device(subdrv_dev, *dma_priv);
+       } else if (IS_ENABLED(CONFIG_IOMMU_DMA))
                iommu_detach_device(priv->mapping, subdrv_dev);
 
        clear_dma_max_seg_size(subdrv_dev);
 }
 
-int exynos_drm_register_dma(struct drm_device *drm, struct device *dev)
+int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
+                           void **dma_priv)
 {
        struct exynos_drm_private *priv = drm->dev_private;
 
@@ -137,13 +146,14 @@ int exynos_drm_register_dma(struct drm_device *drm, struct device *dev)
                priv->mapping = mapping;
        }
 
-       return drm_iommu_attach_device(drm, dev);
+       return drm_iommu_attach_device(drm, dev, dma_priv);
 }
 
-void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev)
+void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
+                              void **dma_priv)
 {
        if (IS_ENABLED(CONFIG_EXYNOS_IOMMU))
-               drm_iommu_detach_device(drm, dev);
+               drm_iommu_detach_device(drm, dev, dma_priv);
 }
 
 void exynos_drm_cleanup_dma(struct drm_device *drm)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h
index d4d21d8..6ae9056 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h
@@ -223,8 +223,10 @@ static inline bool is_drm_iommu_supported(struct drm_device *drm_dev)
        return priv->mapping ? true : false;
 }
 
-int exynos_drm_register_dma(struct drm_device *drm, struct device *dev);
-void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev);
+int exynos_drm_register_dma(struct drm_device *drm, struct device *dev,
+                           void **dma_priv);
+void exynos_drm_unregister_dma(struct drm_device *drm, struct device *dev,
+                              void **dma_priv);
 void exynos_drm_cleanup_dma(struct drm_device *drm);
 
 #ifdef CONFIG_DRM_EXYNOS_DPI

diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimc.c b/drivers/gpu/drm/exynos/exynos_drm_fimc.c
index 8ea2e1d..29ab8be 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_fimc.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimc.c
@@ -97,6 +97,7 @@ struct fimc_scaler {
 struct fimc_context {
        struct exynos_drm_ipp ipp;
        struct drm_device *drm_dev;
+       void            *dma_priv;
        struct device   *dev;
        struct exynos_drm_ipp_task      *task;
        struct exynos_drm_ipp_formats   *formats;
@@ -1133,7 +1134,7 @@ static int fimc_bind(struct device *dev, struct device *master, void *data)
 
        ctx->drm_dev = drm_dev;
        ipp->drm_dev = drm_dev;
-       exynos_drm_register_dma(drm_dev, dev);
+       exynos_drm_register_dma(drm_dev, dev, &ctx->dma_priv);
 
        exynos_drm_ipp_register(dev, ipp, &ipp_funcs,
                        DRM_EXYNOS_IPP_CAP_CROP | DRM_EXYNOS_IPP_CAP_ROTATE |
@@ -1153,7 +1154,7 @@ static void fimc_unbind(struct device *dev, struct device *master,
        struct exynos_drm_ipp *ipp = &ctx->ipp;
 
        exynos_drm_ipp_unregister(dev, ipp);
-       exynos_drm_unregister_dma(drm_dev, dev);
+       exynos_drm_unregister_dma(drm_dev, dev, &ctx->dma_priv);
 }
 
 static const struct component_ops fimc_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
index 21aec38..bb67cad 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
@@ -167,6 +167,7 @@ static struct fimd_driver_data exynos5420_fimd_driver_data = {
 struct fimd_context {
        struct device                   *dev;
        struct drm_device               *drm_dev;
+       void                            *dma_priv;
        struct exynos_drm_crtc          *crtc;
        struct exynos_drm_plane         planes[WINDOWS_NR];
        struct exynos_drm_plane_config  configs[WINDOWS_NR];
@@ -1090,7 +1091,7 @@ static int fimd_bind(struct device *dev, struct device *master, void *data)
        if (is_drm_iommu_supported(drm_dev))
                fimd_clear_channels(ctx->crtc);
 
-       return exynos_drm_register_dma(drm_dev, dev);
+       return exynos_drm_register_dma(drm_dev, dev, &ctx->dma_priv);
 }
 
 static void fimd_unbind(struct device *dev, struct device *master,
@@ -1100,7 +1101,7 @@ static void fimd_unbind(struct device *dev, struct device *master,
 
        fimd_atomic_disable(ctx->crtc);
 
-       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev);
+       exynos_drm_unregister_dma(ctx->drm_dev, ctx->dev, &ctx->dma_priv);
 
        if (ctx->encoder)
                exynos_dpi_remove(ctx->encoder);

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index 2a3382d..fcee33a 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -232,6 +232,7 @@ struct g2d_runqueue_node {
 
 struct g2d_data {
        struct device                   *dev;
+       void                            *dma_priv;
        struct clk                      *gate_clk;
        void __iomem                    *regs;
        int                             irq;
@@ -1409,7 +1410,7 @@ static int g2d_bind(struct device *dev, struct device *master, void *data)
                return ret;
        }
 
-       ret = exynos_drm_register_dma(drm_dev, dev);
+       ret = exynos_drm_register_dma(drm_dev, dev, &g2d->dma_priv);
        if (ret < 0) {
                dev_err(dev, "failed to enable iommu.\n");
                g2d_fini_cmdlist(g2d);
@@ -1434,7 +1435,7 @@ static void g2d_unbind(struct device *dev, struct device *master, void *data)
        priv->g2d_dev = NULL;
 
        cancel_work_sync(&g2d->runqueue_work);
-       exynos_drm_unregister_dma(g2d->drm_dev, dev);
+       exynos_drm_unregister_dma(g2d->drm_dev, dev, &g2d->dma_priv);
 }
 
 static const struct component_ops g2d_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gsc.c b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
index 88b6fca..45e9aee 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_gsc.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
@@ -97,6 +97,7 @@ struct gsc_scaler {
 struct gsc_context {
        struct exynos_drm_ipp ipp;
        struct drm_device *drm_dev;
+       void            *dma_priv;
        struct device   *dev;
        struct exynos_drm_ipp_task      *task;
        struct exynos_drm_ipp_formats   *formats;
@@ -1169,7 +1170,7 @@ static int gsc_bind(struct device *dev, struct device *master, void *data)
 
        ctx->drm_dev = drm_dev;
        ctx->drm_dev = drm_dev;
-       exynos_drm_register_dma(drm_dev, dev);
+       exynos_drm_register_dma(drm_dev, dev, &ctx->dma_priv);
 
        exynos_drm_ipp_register(dev, ipp, &ipp_funcs,
                        DRM_EXYNOS_IPP_CAP_CROP | DRM_EXYNOS_IPP_CAP_ROTATE |
@@ -1189,7 +1190,7 @@ static void gsc_unbind(struct device *dev, struct device *master,
        struct exynos_drm_ipp *ipp = &ctx->ipp;
 
        exynos_drm_ipp_unregister(dev, ipp);
-       exynos_drm_unregister_dma(drm_dev, dev);
+       exynos_drm_unregister_dma(drm_dev, dev, &ctx->dma_priv);
 }
 
 static const struct component_ops gsc_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos_drm_rotator.c b/drivers/gpu/drm/exynos/exynos_drm_rotator.c
index b984829..dafa87b 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_rotator.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_rotator.c
@@ -56,6 +56,7 @@ struct rot_variant {
 struct rot_context {
        struct exynos_drm_ipp ipp;
        struct drm_device *drm_dev;
+       void            *dma_priv;
        struct device   *dev;
        void __iomem    *regs;
        struct clk      *clock;
@@ -243,7 +244,7 @@ static int rotator_bind(struct device *dev, struct device *master, void *data)
 
        rot->drm_dev = drm_dev;
        ipp->drm_dev = drm_dev;
-       exynos_drm_register_dma(drm_dev, dev);
+       exynos_drm_register_dma(drm_dev, dev, &rot->dma_priv);
 
        exynos_drm_ipp_register(dev, ipp, &ipp_funcs,
                           DRM_EXYNOS_IPP_CAP_CROP | DRM_EXYNOS_IPP_CAP_ROTATE,
@@ -261,7 +262,7 @@ static void rotator_unbind(struct device *dev, struct device *master,
        struct exynos_drm_ipp *ipp = &rot->ipp;
 
        exynos_drm_ipp_unregister(dev, ipp);
-       exynos_drm_unregister_dma(rot->drm_dev, rot->dev);
+       exynos_drm_unregister_dma(rot->drm_dev, rot->dev, &rot->dma_priv);
 }
 
 static const struct component_ops rotator_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos_drm_scaler.c b/drivers/gpu/drm/exynos/exynos_drm_scaler.c
index 497973e..93c43c8 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_scaler.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_scaler.c
@@ -39,6 +39,7 @@ struct scaler_data {
 struct scaler_context {
        struct exynos_drm_ipp           ipp;
        struct drm_device               *drm_dev;
+       void                            *dma_priv;
        struct device                   *dev;
        void __iomem                    *regs;
        struct clk                      *clock[SCALER_MAX_CLK];
@@ -450,7 +451,7 @@ static int scaler_bind(struct device *dev, struct device *master, void *data)
 
        scaler->drm_dev = drm_dev;
        ipp->drm_dev = drm_dev;
-       exynos_drm_register_dma(drm_dev, dev);
+       exynos_drm_register_dma(drm_dev, dev, &scaler->dma_priv);
 
        exynos_drm_ipp_register(dev, ipp, &ipp_funcs,
                        DRM_EXYNOS_IPP_CAP_CROP | DRM_EXYNOS_IPP_CAP_ROTATE |
@@ -470,7 +471,8 @@ static void scaler_unbind(struct device *dev, struct device *master,
        struct exynos_drm_ipp *ipp = &scaler->ipp;
 
        exynos_drm_ipp_unregister(dev, ipp);
-       exynos_drm_unregister_dma(scaler->drm_dev, scaler->dev);
+       exynos_drm_unregister_dma(scaler->drm_dev, scaler->dev,
+                                 &scaler->dma_priv);
 }
 
 static const struct component_ops scaler_component_ops = {

diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
index 38ae9c3..21b726b 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_mixer.c
+++ b/drivers/gpu/drm/exynos/exynos_mixer.c
@@ -94,6 +94,7 @@ struct mixer_context {
        struct platform_device *pdev;
        struct device           *dev;
        struct drm_device       *drm_dev;
+       void                    *dma_priv;
        struct exynos_drm_crtc  *crtc;
        struct exynos_drm_plane planes[MIXER_WIN_NR];
        unsigned long           flags;
@@ -894,12 +895,14 @@ static int mixer_initialize(struct mixer_context *mixer_ctx,
                }
        }
 
-       return exynos_drm_register_dma(drm_dev, mixer_ctx->dev);
+       return exynos_drm_register_dma(drm_dev, mixer_ctx->dev,
+                                      &mixer_ctx->dma_priv);
 }
 
 static void mixer_ctx_remove(struct mixer_context *mixer_ctx)
 {
-       exynos_drm_unregister_dma(mixer_ctx->drm_dev, mixer_ctx->dev);
+       exynos_drm_unregister_dma(mixer_ctx->drm_dev, mixer_ctx->dev,
+                                 &mixer_ctx->dma_priv);
 }
 
 static int mixer_enable_vblank(struct exynos_drm_crtc *crtc)