From: ChiYuan Huang <cy_huang@xxxxxxxxxxx>
Add 'richtek,bled-ocp-microamp' property parsing in
device_property_init function.
This value may configure prior to the kernel driver. If it's not specified in
devicetree, keep the original setting. Else, use clamp to align the
value in min/max range and also roundup to choose the best selector.
Reported-by: Lucas Tsai <lucas_tsai@xxxxxxxxxxx>
Signed-off-by: ChiYuan Huang <cy_huang@xxxxxxxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
---
Hi, Daniel:
I may use the wrong macro, must be 'DIV_ROUND_UP', not 'roundup'.
the v4 is to fix it.
Since v4
- Fix wrong macro usage, must be 'DIV_ROUND_UP', not 'roundup'
Since v2:
- Prase the 'richtek,bled-ocp-microamp', clamp the value in min/max range, and
roundup to get the best selector.
---
drivers/video/backlight/rt4831-backlight.c | 33 +++++++++++++++++++++++++++++-
1 file changed, 32 insertions(+), 1 deletion(-)
diff --git a/drivers/video/backlight/rt4831-backlight.c b/drivers/video/backlight/rt4831-backlight.c
index 42155c7..eb8c59e 100644
--- a/drivers/video/backlight/rt4831-backlight.c
+++ b/drivers/video/backlight/rt4831-backlight.c
@@ -12,6 +12,7 @@
#define RT4831_REG_BLCFG 0x02
#define RT4831_REG_BLDIML 0x04
#define RT4831_REG_ENABLE 0x08
+#define RT4831_REG_BLOPT2 0x11
#define RT4831_BLMAX_BRIGHTNESS 2048
@@ -23,6 +24,11 @@
#define RT4831_BLDIML_MASK GENMASK(2, 0)
#define RT4831_BLDIMH_MASK GENMASK(10, 3)
#define RT4831_BLDIMH_SHIFT 3
+#define RT4831_BLOCP_MASK GENMASK(1, 0)
+
+#define RT4831_BLOCP_MINUA 900000
+#define RT4831_BLOCP_MAXUA 1800000
+#define RT4831_BLOCP_STEPUA 300000
struct rt4831_priv {
struct device *dev;
@@ -85,7 +91,7 @@ static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
{
struct device *dev = priv->dev;
u8 propval;
- u32 brightness;
+ u32 brightness, ocp_uA;
unsigned int val = 0;
int ret;
@@ -120,6 +126,31 @@ static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
if (ret)
return ret;
+ /*
+ * This OCP level is used to protect and limit the inductor current.
+ * If inductor peak current reach the level, low-side MOSFET will be
+ * turned off. Meanwhile, the output channel current may be limited.
+ * To match the configured channel current, the inductor chosen must
+ * be higher than the OCP level.
+ *
+ * Not like the OVP level, the default 21V can be used in the most
+ * application. But if the chosen OCP level is smaller than needed,
+ * it will also affect the backlight channel output current to be
+ * smaller than the register setting.
+ */
+ ret = device_property_read_u32(dev, "richtek,bled-ocp-microamp",
+ &ocp_uA);
+ if (!ret) {
+ ocp_uA = clamp_val(ocp_uA, RT4831_BLOCP_MINUA,
+ RT4831_BLOCP_MAXUA);
+ val = DIV_ROUND_UP(ocp_uA - RT4831_BLOCP_MINUA,
+ RT4831_BLOCP_STEPUA);
+ ret = regmap_update_bits(priv->regmap, RT4831_REG_BLOPT2,
+ RT4831_BLOCP_MASK, val);
+ if (ret)
+ return ret;
+ }
+
ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
if (ret) {
dev_err(dev, "richtek,channel-use DT property missing\n");
--
2.7.4
