OMAP: DSS2: Add new FEAT definitions for features missing from OMAP2

OMAP2 doesn't have CPR, PRELOAD nor FIR_COEF_V registers. Add new
feature definitions for those, and check the feature before accessing
those registers.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

4 files changed, 105 insertions, 58 deletions

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index a9eebd8e79fe..ee2052f2ea02 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -159,7 +159,8 @@ void dispc_save_context(void)
         SR(TIMING_V(OMAP_DSS_CHANNEL_LCD));
         SR(POL_FREQ(OMAP_DSS_CHANNEL_LCD));
         SR(DIVISORo(OMAP_DSS_CHANNEL_LCD));
-        SR(GLOBAL_ALPHA);
+        if (dss_has_feature(FEAT_GLOBAL_ALPHA))
+                SR(GLOBAL_ALPHA);
         SR(SIZE_MGR(OMAP_DSS_CHANNEL_DIGIT));
         SR(SIZE_MGR(OMAP_DSS_CHANNEL_LCD));
         if (dss_has_feature(FEAT_MGR_LCD2)) {
@@ -189,20 +190,25 @@ void dispc_save_context(void)
         SR(DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD));
         SR(DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD));
 
-        SR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
-        SR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
-        SR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        if (dss_has_feature(FEAT_CPR)) {
+                SR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
+                SR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
+                SR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        }
         if (dss_has_feature(FEAT_MGR_LCD2)) {
-                SR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
-                SR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
-                SR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
+                if (dss_has_feature(FEAT_CPR)) {
+                        SR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
+                        SR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
+                        SR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
+                }
 
                 SR(DATA_CYCLE1(OMAP_DSS_CHANNEL_LCD2));
                 SR(DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD2));
                 SR(DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD2));
         }
 
-        SR(OVL_PRELOAD(OMAP_DSS_GFX));
+        if (dss_has_feature(FEAT_PRELOAD))
+                SR(OVL_PRELOAD(OMAP_DSS_GFX));
 
         /* VID1 */
         SR(OVL_BA0(OMAP_DSS_VIDEO1));
@@ -227,8 +233,10 @@ void dispc_save_context(void)
         for (i = 0; i < 5; i++)
                 SR(OVL_CONV_COEF(OMAP_DSS_VIDEO1, i));
 
-        for (i = 0; i < 8; i++)
-                SR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, i));
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                for (i = 0; i < 8; i++)
+                        SR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, i));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 SR(OVL_BA0_UV(OMAP_DSS_VIDEO1));
@@ -249,7 +257,8 @@ void dispc_save_context(void)
         if (dss_has_feature(FEAT_ATTR2))
                 SR(OVL_ATTRIBUTES2(OMAP_DSS_VIDEO1));
 
-        SR(OVL_PRELOAD(OMAP_DSS_VIDEO1));
+        if (dss_has_feature(FEAT_PRELOAD))
+                SR(OVL_PRELOAD(OMAP_DSS_VIDEO1));
 
         /* VID2 */
         SR(OVL_BA0(OMAP_DSS_VIDEO2));
@@ -274,8 +283,10 @@ void dispc_save_context(void)
         for (i = 0; i < 5; i++)
                 SR(OVL_CONV_COEF(OMAP_DSS_VIDEO2, i));
 
-        for (i = 0; i < 8; i++)
-                SR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, i));
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                for (i = 0; i < 8; i++)
+                        SR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, i));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 SR(OVL_BA0_UV(OMAP_DSS_VIDEO2));
@@ -296,7 +307,8 @@ void dispc_save_context(void)
         if (dss_has_feature(FEAT_ATTR2))
                 SR(OVL_ATTRIBUTES2(OMAP_DSS_VIDEO2));
 
-        SR(OVL_PRELOAD(OMAP_DSS_VIDEO2));
+        if (dss_has_feature(FEAT_PRELOAD))
+                SR(OVL_PRELOAD(OMAP_DSS_VIDEO2));
 
         if (dss_has_feature(FEAT_CORE_CLK_DIV))
                 SR(DIVISOR);
@@ -318,7 +330,8 @@ void dispc_restore_context(void)
         RR(TIMING_V(OMAP_DSS_CHANNEL_LCD));
         RR(POL_FREQ(OMAP_DSS_CHANNEL_LCD));
         RR(DIVISORo(OMAP_DSS_CHANNEL_LCD));
-        RR(GLOBAL_ALPHA);
+        if (dss_has_feature(FEAT_GLOBAL_ALPHA))
+                RR(GLOBAL_ALPHA);
         RR(SIZE_MGR(OMAP_DSS_CHANNEL_DIGIT));
         RR(SIZE_MGR(OMAP_DSS_CHANNEL_LCD));
         if (dss_has_feature(FEAT_MGR_LCD2)) {
@@ -348,20 +361,25 @@ void dispc_restore_context(void)
         RR(DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD));
         RR(DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD));
 
-        RR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
-        RR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
-        RR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        if (dss_has_feature(FEAT_CPR)) {
+                RR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
+                RR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
+                RR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        }
         if (dss_has_feature(FEAT_MGR_LCD2)) {
                 RR(DATA_CYCLE1(OMAP_DSS_CHANNEL_LCD2));
                 RR(DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD2));
                 RR(DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD2));
 
-                RR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
-                RR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
-                RR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
+                if (dss_has_feature(FEAT_CPR)) {
+                        RR(CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
+                        RR(CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
+                        RR(CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
+                }
         }
 
-        RR(OVL_PRELOAD(OMAP_DSS_GFX));
+        if (dss_has_feature(FEAT_PRELOAD))
+                RR(OVL_PRELOAD(OMAP_DSS_GFX));
 
         /* VID1 */
         RR(OVL_BA0(OMAP_DSS_VIDEO1));
@@ -386,8 +404,10 @@ void dispc_restore_context(void)
         for (i = 0; i < 5; i++)
                 RR(OVL_CONV_COEF(OMAP_DSS_VIDEO1, i));
 
-        for (i = 0; i < 8; i++)
-                RR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, i));
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                for (i = 0; i < 8; i++)
+                        RR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, i));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 RR(OVL_BA0_UV(OMAP_DSS_VIDEO1));
@@ -408,7 +428,8 @@ void dispc_restore_context(void)
         if (dss_has_feature(FEAT_ATTR2))
                 RR(OVL_ATTRIBUTES2(OMAP_DSS_VIDEO1));
 
-        RR(OVL_PRELOAD(OMAP_DSS_VIDEO1));
+        if (dss_has_feature(FEAT_PRELOAD))
+                RR(OVL_PRELOAD(OMAP_DSS_VIDEO1));
 
         /* VID2 */
         RR(OVL_BA0(OMAP_DSS_VIDEO2));
@@ -433,8 +454,10 @@ void dispc_restore_context(void)
         for (i = 0; i < 5; i++)
                 RR(OVL_CONV_COEF(OMAP_DSS_VIDEO2, i));
 
-        for (i = 0; i < 8; i++)
-                RR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, i));
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                for (i = 0; i < 8; i++)
+                        RR(OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, i));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 RR(OVL_BA0_UV(OMAP_DSS_VIDEO2));
@@ -455,7 +478,8 @@ void dispc_restore_context(void)
         if (dss_has_feature(FEAT_ATTR2))
                 RR(OVL_ATTRIBUTES2(OMAP_DSS_VIDEO2));
 
-        RR(OVL_PRELOAD(OMAP_DSS_VIDEO2));
+        if (dss_has_feature(FEAT_PRELOAD))
+                RR(OVL_PRELOAD(OMAP_DSS_VIDEO2));
 
         if (dss_has_feature(FEAT_CORE_CLK_DIV))
                 RR(DIVISOR);
@@ -2650,7 +2674,8 @@ void dispc_dump_regs(struct seq_file *s)
         DUMPREG(DISPC_TIMING_V(OMAP_DSS_CHANNEL_LCD));
         DUMPREG(DISPC_POL_FREQ(OMAP_DSS_CHANNEL_LCD));
         DUMPREG(DISPC_DIVISORo(OMAP_DSS_CHANNEL_LCD));
-        DUMPREG(DISPC_GLOBAL_ALPHA);
+        if (dss_has_feature(FEAT_GLOBAL_ALPHA))
+                DUMPREG(DISPC_GLOBAL_ALPHA);
         DUMPREG(DISPC_SIZE_MGR(OMAP_DSS_CHANNEL_DIGIT));
         DUMPREG(DISPC_SIZE_MGR(OMAP_DSS_CHANNEL_LCD));
         if (dss_has_feature(FEAT_MGR_LCD2)) {
@@ -2681,20 +2706,25 @@ void dispc_dump_regs(struct seq_file *s)
         DUMPREG(DISPC_DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD));
         DUMPREG(DISPC_DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD));
 
-        DUMPREG(DISPC_CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
-        DUMPREG(DISPC_CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
-        DUMPREG(DISPC_CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        if (dss_has_feature(FEAT_CPR)) {
+                DUMPREG(DISPC_CPR_COEF_R(OMAP_DSS_CHANNEL_LCD));
+                DUMPREG(DISPC_CPR_COEF_G(OMAP_DSS_CHANNEL_LCD));
+                DUMPREG(DISPC_CPR_COEF_B(OMAP_DSS_CHANNEL_LCD));
+        }
         if (dss_has_feature(FEAT_MGR_LCD2)) {
                 DUMPREG(DISPC_DATA_CYCLE1(OMAP_DSS_CHANNEL_LCD2));
                 DUMPREG(DISPC_DATA_CYCLE2(OMAP_DSS_CHANNEL_LCD2));
                 DUMPREG(DISPC_DATA_CYCLE3(OMAP_DSS_CHANNEL_LCD2));
 
-                DUMPREG(DISPC_CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
-                DUMPREG(DISPC_CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
-                DUMPREG(DISPC_CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
+                if (dss_has_feature(FEAT_CPR)) {
+                        DUMPREG(DISPC_CPR_COEF_R(OMAP_DSS_CHANNEL_LCD2));
+                        DUMPREG(DISPC_CPR_COEF_G(OMAP_DSS_CHANNEL_LCD2));
+                        DUMPREG(DISPC_CPR_COEF_B(OMAP_DSS_CHANNEL_LCD2));
+                }
         }
 
-        DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_GFX));
+        if (dss_has_feature(FEAT_PRELOAD))
+                DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_GFX));
 
         DUMPREG(DISPC_OVL_BA0(OMAP_DSS_VIDEO1));
         DUMPREG(DISPC_OVL_BA1(OMAP_DSS_VIDEO1));
@@ -2745,14 +2775,16 @@ void dispc_dump_regs(struct seq_file *s)
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO1, 2));
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO1, 3));
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO1, 4));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 0));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 1));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 2));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 3));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 4));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 5));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 6));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 7));
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 0));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 1));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 2));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 3));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 4));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 5));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 6));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO1, 7));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 DUMPREG(DISPC_OVL_BA0_UV(OMAP_DSS_VIDEO1));
@@ -2813,14 +2845,17 @@ void dispc_dump_regs(struct seq_file *s)
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO2, 2));
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO2, 3));
         DUMPREG(DISPC_OVL_CONV_COEF(OMAP_DSS_VIDEO2, 4));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 0));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 1));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 2));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 3));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 4));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 5));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 6));
-        DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 7));
+
+        if (dss_has_feature(FEAT_FIR_COEF_V)) {
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 0));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 1));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 2));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 3));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 4));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 5));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 6));
+                DUMPREG(DISPC_OVL_FIR_COEF_V(OMAP_DSS_VIDEO2, 7));
+        }
 
         if (dss_has_feature(FEAT_HANDLE_UV_SEPARATE)) {
                 DUMPREG(DISPC_OVL_BA0_UV(OMAP_DSS_VIDEO2));
@@ -2859,8 +2894,10 @@ void dispc_dump_regs(struct seq_file *s)
         if (dss_has_feature(FEAT_ATTR2))
                 DUMPREG(DISPC_OVL_ATTRIBUTES2(OMAP_DSS_VIDEO2));
 
-        DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_VIDEO1));
-        DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_VIDEO2));
+        if (dss_has_feature(FEAT_PRELOAD)) {
+                DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_VIDEO1));
+                DUMPREG(DISPC_OVL_PRELOAD(OMAP_DSS_VIDEO2));
+        }
 
         dss_clk_disable(DSS_CLK_ICK | DSS_CLK_FCK);
 #undef DUMPREG
diff --git a/drivers/video/omap2/dss/dss_features.c b/drivers/video/omap2/dss/dss_features.c
index a588380eec22..bd420f9650c9 100644
--- a/drivers/video/omap2/dss/dss_features.c
+++ b/drivers/video/omap2/dss/dss_features.c
@@ -287,7 +287,8 @@ static const struct omap_dss_features omap3430_dss_features = {
                 FEAT_FUNCGATED | FEAT_ROWREPEATENABLE |
                 FEAT_LINEBUFFERSPLIT | FEAT_RESIZECONF |
                 FEAT_DSI_PLL_FREQSEL | FEAT_DSI_REVERSE_TXCLKESC |
-                FEAT_VENC_REQUIRES_TV_DAC_CLK,
+                FEAT_VENC_REQUIRES_TV_DAC_CLK | FEAT_CPR | FEAT_PRELOAD |
+                FEAT_FIR_COEF_V,
 
         .num_mgrs = 2,
         .num_ovls = 3,
@@ -307,7 +308,8 @@ static const struct omap_dss_features omap3630_dss_features = {
                 FEAT_PRE_MULT_ALPHA | FEAT_FUNCGATED |
                 FEAT_ROWREPEATENABLE | FEAT_LINEBUFFERSPLIT |
                 FEAT_RESIZECONF | FEAT_DSI_PLL_PWR_BUG |
-                FEAT_DSI_PLL_FREQSEL,
+                FEAT_DSI_PLL_FREQSEL | FEAT_CPR | FEAT_PRELOAD |
+                FEAT_FIR_COEF_V,
 
         .num_mgrs = 2,
         .num_ovls = 3,
@@ -328,7 +330,8 @@ static const struct omap_dss_features omap4430_es1_0_dss_features  = {
                 FEAT_MGR_LCD2 | FEAT_GLOBAL_ALPHA_VID1 |
                 FEAT_CORE_CLK_DIV | FEAT_LCD_CLK_SRC |
                 FEAT_DSI_DCS_CMD_CONFIG_VC | FEAT_DSI_VC_OCP_WIDTH |
-                FEAT_DSI_GNQ | FEAT_HANDLE_UV_SEPARATE | FEAT_ATTR2,
+                FEAT_DSI_GNQ | FEAT_HANDLE_UV_SEPARATE | FEAT_ATTR2 |
+                FEAT_CPR | FEAT_PRELOAD | FEAT_FIR_COEF_V,
 
         .num_mgrs = 3,
         .num_ovls = 3,
@@ -349,7 +352,8 @@ static const struct omap_dss_features omap4_dss_features = {
                 FEAT_CORE_CLK_DIV | FEAT_LCD_CLK_SRC |
                 FEAT_DSI_DCS_CMD_CONFIG_VC | FEAT_DSI_VC_OCP_WIDTH |
                 FEAT_DSI_GNQ | FEAT_HDMI_CTS_SWMODE |
-                FEAT_HANDLE_UV_SEPARATE | FEAT_ATTR2,
+                FEAT_HANDLE_UV_SEPARATE | FEAT_ATTR2 | FEAT_CPR |
+                FEAT_PRELOAD | FEAT_FIR_COEF_V,
 
         .num_mgrs = 3,
         .num_ovls = 3,
diff --git a/drivers/video/omap2/dss/dss_features.h b/drivers/video/omap2/dss/dss_features.h
index 3058e24946ad..5be8103a159e 100644
--- a/drivers/video/omap2/dss/dss_features.h
+++ b/drivers/video/omap2/dss/dss_features.h
@@ -52,6 +52,9 @@ enum dss_feat_id {
         FEAT_HANDLE_UV_SEPARATE         = 1 << 20,
         FEAT_ATTR2                      = 1 << 21,
         FEAT_VENC_REQUIRES_TV_DAC_CLK   = 1 << 22,
+        FEAT_CPR                        = 1 << 23,
+        FEAT_PRELOAD                    = 1 << 24,
+        FEAT_FIR_COEF_V                 = 1 << 25,
 };
 
 /* DSS register field id */
diff --git a/drivers/video/omap2/dss/overlay.c b/drivers/video/omap2/dss/overlay.c
index 0f08025b1f0e..cfbfc57e9582 100644
--- a/drivers/video/omap2/dss/overlay.c
+++ b/drivers/video/omap2/dss/overlay.c
@@ -238,6 +238,9 @@ static ssize_t overlay_global_alpha_store(struct omap_overlay *ovl,
         u8 alpha;
         struct omap_overlay_info info;
 
+        if (!dss_has_feature(FEAT_GLOBAL_ALPHA))
+                return -ENODEV;
+
         r = kstrtou8(buf, 0, &alpha);
         if (r)
                 return r;