* [PATCH v3 1/2] dt-bindings: backlight: rt4831: Add the new ocp level property
2022-06-09 2:22 [PATCH v3 0/2] Add the property to make backlight OCP level selectable cy_huang
@ 2022-06-09 2:22 ` cy_huang
2022-06-09 9:26 ` Daniel Thompson
2022-06-09 10:31 ` Krzysztof Kozlowski
2022-06-09 2:22 ` [PATCH v3 2/2] backlight: rt4831: Apply ocp level from devicetree cy_huang
1 sibling, 2 replies; 5+ messages in thread
From: cy_huang @ 2022-06-09 2:22 UTC (permalink / raw)
To: robh+dt, krzysztof.kozlowski+dt, lee.jones, daniel.thompson,
jingoohan1
Cc: pavel, deller, cy_huang, lucas_tsai, devicetree, dri-devel,
linux-fbdev, linux-leds, linux-kernel
From: ChiYuan Huang <cy_huang@richtek.com>
Add 'richtek,bled-ocp-microamp' property to make it chooseable.
The wrong backlight ocp level may affect the backlight channel output
current smaller than configured.
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
---
Since v3:
- Refine the description for backlight ocp property.
- Use the enum to list the supported value.
Since v2:
- Change the property name from 'richtek,bled-ocp-sel' to 'richtek,bled-ocp-microamp'.
---
.../devicetree/bindings/leds/backlight/richtek,rt4831-backlight.yaml | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/Documentation/devicetree/bindings/leds/backlight/richtek,rt4831-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/richtek,rt4831-backlight.yaml
index e0ac686..99e9e13 100644
--- a/Documentation/devicetree/bindings/leds/backlight/richtek,rt4831-backlight.yaml
+++ b/Documentation/devicetree/bindings/leds/backlight/richtek,rt4831-backlight.yaml
@@ -47,6 +47,11 @@ properties:
minimum: 0
maximum: 3
+ richtek,bled-ocp-microamp:
+ description: |
+ Backlight over current protection level.
+ enum: [900000, 1200000, 1500000, 1800000]
+
richtek,channel-use:
description: |
Backlight LED channel to be used.
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v3 2/2] backlight: rt4831: Apply ocp level from devicetree
2022-06-09 2:22 [PATCH v3 0/2] Add the property to make backlight OCP level selectable cy_huang
2022-06-09 2:22 ` [PATCH v3 1/2] dt-bindings: backlight: rt4831: Add the new ocp level property cy_huang
@ 2022-06-09 2:22 ` cy_huang
1 sibling, 0 replies; 5+ messages in thread
From: cy_huang @ 2022-06-09 2:22 UTC (permalink / raw)
To: robh+dt, krzysztof.kozlowski+dt, lee.jones, daniel.thompson,
jingoohan1
Cc: pavel, deller, cy_huang, lucas_tsai, devicetree, dri-devel,
linux-fbdev, linux-leds, linux-kernel
From: ChiYuan Huang <cy_huang@richtek.com>
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@richtek.com>
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
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..8c2001b 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 = roundup(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
^ permalink raw reply related [flat|nested] 5+ messages in thread