OMAP: DSS2: DISPC: Fix context save/restore

The current method of saving and restoring the context could cause a
restore before saving, effectively "restoring" zero values to registers.

Add ctx_valid field to indicate if the saved context is valid and can be
restored.

Also restructure the code to save the ctx_loss_count in save_context(),
which makes more sense than the previous method of storing new
ctx_loss_count in dispc_need_ctx_restore.

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

1 files changed, 38 insertions, 59 deletions

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index 7c1b7c1e4b6..0f3961a1ce2 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -114,6 +114,7 @@ static struct {
         u32 error_irqs;
         struct work_struct error_work;
 
+        bool            ctx_valid;
         u32             ctx[DISPC_SZ_REGS / sizeof(u32)];
 
 #ifdef CONFIG_OMAP2_DSS_COLLECT_IRQ_STATS
@@ -146,6 +147,23 @@ static inline u32 dispc_read_reg(const u16 idx)
         return __raw_readl(dispc.base + idx);
 }
 
+static int dispc_get_ctx_loss_count(void)
+{
+        struct device *dev = &dispc.pdev->dev;
+        struct omap_display_platform_data *pdata = dev->platform_data;
+        struct omap_dss_board_info *board_data = pdata->board_data;
+        int cnt;
+
+        if (!board_data->get_context_loss_count)
+                return -ENOENT;
+
+        cnt = board_data->get_context_loss_count(dev);
+
+        WARN_ONCE(cnt < 0, "get_context_loss_count failed: %d\n", cnt);
+
+        return cnt;
+}
+
 #define SR(reg) \
         dispc.ctx[DISPC_##reg / sizeof(u32)] = dispc_read_reg(DISPC_##reg)
 #define RR(reg) \
@@ -322,14 +340,30 @@ static void dispc_save_context(void)
 
         if (dss_has_feature(FEAT_CORE_CLK_DIV))
                 SR(DIVISOR);
+
+        dispc.ctx_loss_cnt = dispc_get_ctx_loss_count();
+        dispc.ctx_valid = true;
+
+        DSSDBG("context saved, ctx_loss_count %d\n", dispc.ctx_loss_cnt);
 }
 
 static void dispc_restore_context(void)
 {
-        int i;
+        int i, ctx;
 
         DSSDBG("dispc_restore_context\n");
 
+        if (!dispc.ctx_valid)
+                return;
+
+        ctx = dispc_get_ctx_loss_count();
+
+        if (ctx >= 0 && ctx == dispc.ctx_loss_cnt)
+                return;
+
+        DSSDBG("ctx_loss_count: saved %d, current %d\n",
+                        dispc.ctx_loss_cnt, ctx);
+
         /*RR(IRQENABLE);*/
         /*RR(CONTROL);*/
         RR(CONFIG);
@@ -508,65 +542,13 @@ static void dispc_restore_context(void)
          * the context is fully restored
          */
         RR(IRQENABLE);
+
+        DSSDBG("context restored\n");
 }
 
 #undef SR
 #undef RR
 
-static void dispc_init_ctx_loss_count(void)
-{
-        struct device *dev = &dispc.pdev->dev;
-        struct omap_display_platform_data *pdata = dev->platform_data;
-        struct omap_dss_board_info *board_data = pdata->board_data;
-        int cnt = 0;
-
-        /*
-         * get_context_loss_count returns negative on error. We'll ignore the
-         * error and store the error to ctx_loss_cnt, which will cause
-         * dispc_need_ctx_restore() call to return true.
-         */
-
-        if (board_data->get_context_loss_count)
-                cnt = board_data->get_context_loss_count(dev);
-
-        WARN_ON(cnt < 0);
-
-        dispc.ctx_loss_cnt = cnt;
-
-        DSSDBG("initial ctx_loss_cnt %u\n", cnt);
-}
-
-static bool dispc_need_ctx_restore(void)
-{
-        struct device *dev = &dispc.pdev->dev;
-        struct omap_display_platform_data *pdata = dev->platform_data;
-        struct omap_dss_board_info *board_data = pdata->board_data;
-        int cnt;
-
-        /*
-         * If get_context_loss_count is not available, assume that we need
-         * context restore always.
-         */
-        if (!board_data->get_context_loss_count)
-                return true;
-
-        cnt = board_data->get_context_loss_count(dev);
-        if (cnt < 0) {
-                dev_err(dev, "getting context loss count failed, will force "
-                                "context restore\n");
-                dispc.ctx_loss_cnt = cnt;
-                return true;
-        }
-
-        if (cnt == dispc.ctx_loss_cnt)
-                return false;
-
-        DSSDBG("ctx_loss_cnt %d -> %d\n", dispc.ctx_loss_cnt, cnt);
-        dispc.ctx_loss_cnt = cnt;
-
-        return true;
-}
-
 int dispc_runtime_get(void)
 {
         int r;
@@ -3709,8 +3691,6 @@ static int omap_dispchw_probe(struct platform_device *pdev)
                 goto err_irq;
         }
 
-        dispc_init_ctx_loss_count();
-
         pm_runtime_enable(&pdev->dev);
 
         r = dispc_runtime_get();
@@ -3769,8 +3749,7 @@ static int dispc_runtime_resume(struct device *dev)
                 return r;
 
         clk_enable(dispc.dss_clk);
-        if (dispc_need_ctx_restore())
-                dispc_restore_context();
+        dispc_restore_context();
 
         return 0;
 }