backlight: qcom-wled: Correct the sync_toggle sequence

As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are set-then-cleared.
But, the FSC and brightness sync takes place when the sync bits are
set (e.g. on a rising edge). So the hardware team recommends a
clear-then-set approach in order to guarantee such a transition
regardless of the previous register state.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index e9fbe24..7c02f87 100644 (file)
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -337,13 +337,13 @@ static int wled3_sync_toggle(struct wled *wled)
 
        rc = regmap_update_bits(wled->regmap,
                                wled->sink_addr + WLED3_SINK_REG_SYNC,
-                               mask, mask);
+                               mask, WLED3_SINK_REG_SYNC_CLEAR);
        if (rc < 0)
                return rc;
 
        rc = regmap_update_bits(wled->regmap,
                                wled->sink_addr + WLED3_SINK_REG_SYNC,
-                               mask, WLED3_SINK_REG_SYNC_CLEAR);
+                               mask, mask);
 
        return rc;
 }
@@ -353,17 +353,17 @@ static int wled5_mod_sync_toggle(struct wled *wled)
        int rc;
        u8 val;
 
-       val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
-                                            WLED5_SINK_REG_SYNC_MOD_B_BIT;
        rc = regmap_update_bits(wled->regmap,
                                wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
-                               WLED5_SINK_REG_SYNC_MASK, val);
+                               WLED5_SINK_REG_SYNC_MASK, 0);
        if (rc < 0)
                return rc;
 
+       val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
+                                            WLED5_SINK_REG_SYNC_MOD_B_BIT;
        return regmap_update_bits(wled->regmap,
                                  wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
-                                 WLED5_SINK_REG_SYNC_MASK, 0);
+                                 WLED5_SINK_REG_SYNC_MASK, val);
 }
 
 static int wled_ovp_fault_status(struct wled *wled, bool *fault_set)