Re: [PATCH 1/5] backlight: Add GPIO-based backlight driver

T24gU2F0dXJkYXksIE5vdmVtYmVyIDI0LCAyMDEyIDE6MzUgQU0sIExhdXJlbnQgUGluY2hhcnQg
d3JvdGUNCj4gDQo+IFNpZ25lZC1vZmYtYnk6IExhdXJlbnQgUGluY2hhcnQgPGxhdXJlbnQucGlu
Y2hhcnRAaWRlYXNvbmJvYXJkLmNvbT4NCj4gLS0tDQo+ICBkcml2ZXJzL3ZpZGVvL2JhY2tsaWdo
dC9LY29uZmlnICAgICAgICAgIHwgICAgNyArKw0KPiAgZHJpdmVycy92aWRlby9iYWNrbGlnaHQv
TWFrZWZpbGUgICAgICAgICB8ICAgIDEgKw0KPiAgZHJpdmVycy92aWRlby9iYWNrbGlnaHQvZ3Bp
b19iYWNrbGlnaHQuYyB8ICAxNTggKysrKysrKysrKysrKysrKysrKysrKysrKysrKysrDQo+ICBp
bmNsdWRlL3ZpZGVvL2dwaW9fYmFja2xpZ2h0LmggICAgICAgICAgIHwgICAyMSArKysrDQo+ICA0
IGZpbGVzIGNoYW5nZWQsIDE4NyBpbnNlcnRpb25zKCspLCAwIGRlbGV0aW9ucygtKQ0KPiAgY3Jl
YXRlIG1vZGUgMTAwNjQ0IGRyaXZlcnMvdmlkZW8vYmFja2xpZ2h0L2dwaW9fYmFja2xpZ2h0LmMN
Cj4gIGNyZWF0ZSBtb2RlIDEwMDY0NCBpbmNsdWRlL3ZpZGVvL2dwaW9fYmFja2xpZ2h0LmgNCg0K
Wy4uLl0NCg0KPiArc3RhdGljIGludCBfX2RldmluaXQgZ3Bpb19iYWNrbGlnaHRfcHJvYmUoc3Ry
dWN0IHBsYXRmb3JtX2RldmljZSAqcGRldikNCj4gK3sNCj4gKwlzdHJ1Y3QgZ3Bpb19iYWNrbGln
aHRfcGxhdGZvcm1fZGF0YSAqcGRhdGEgPSBwZGV2LT5kZXYucGxhdGZvcm1fZGF0YTsNCj4gKwlz
dHJ1Y3QgYmFja2xpZ2h0X3Byb3BlcnRpZXMgcHJvcHM7DQo+ICsJc3RydWN0IGJhY2tsaWdodF9k
ZXZpY2UgKmJsOw0KPiArCXN0cnVjdCBncGlvX2JhY2tsaWdodCAqZ2JsOw0KPiArCWludCByZXQ7
DQo+ICsNCj4gKwlnYmwgPSBkZXZtX2t6YWxsb2MoJnBkZXYtPmRldiwgc2l6ZW9mKCpnYmwpLCBH
RlBfS0VSTkVMKTsNCj4gKwlpZiAoZ2JsID09IE5VTEwpDQo+ICsJCXJldHVybiAtRU5PTUVNOw0K
PiArDQo+ICsJZ2JsLT5kZXYgPSAmcGRldi0+ZGV2Ow0KPiArDQo+ICsJaWYgKCFwZGF0YSkgew0K
PiArCQlkZXZfZXJyKCZwZGV2LT5kZXYsICJmYWlsZWQgdG8gZmluZCBwbGF0Zm9ybSBkYXRhXG4i
KTsNCj4gKwkJcmV0dXJuIC1FTk9ERVY7DQo+ICsJfQ0KPiArDQo+ICsJZ2JsLT5mYmRldiA9IHBk
YXRhLT5mYmRldjsNCj4gKwlnYmwtPmdwaW8gPSBwZGF0YS0+Z3BpbzsNCj4gKwlnYmwtPmFjdGl2
ZSA9IHBkYXRhLT5hY3RpdmVfbG93ID8gMCA6IDE7DQo+ICsNCj4gKwlyZXQgPSBkZXZtX2dwaW9f
cmVxdWVzdF9vbmUoZ2JsLT5kZXYsIGdibC0+Z3BpbywgR1BJT0ZfRElSX09VVCwNCj4gKwkJCQkg
ICAgcGRhdGEtPm5hbWUpOw0KDQpQbGVhc2UgdXNlIEdQSU9GX0lOSVQgZmxhZ3MgaWYgeW91IHdh
bnQgdG8gdHVybiBvZmYgR1BJTyBiYWNrbGlnaHQuDQpJZiBnYmwtPmFjdGl2ZSBpcyBpbnZlcnRl
ZCwgR1BJT0ZfSU5JVF9ISUdIIGNhbiBiZSB1c2VkIGFzIGJlbG93Og0KDQoJcmV0ID0gZGV2bV9n
cGlvX3JlcXVlc3Rfb25lKGdibC0+ZGV2LCBnYmwtPmdwaW8sDQoJCQkJICAgIEdQSU9GX0RJUl9P
VVQgfCAoZ2JsLT5hY3RpdmUgPw0KCQkJCSAgICBHUElPRl9JTklUX0xPVyA6IEdQSU9GX0lOSVRf
SElHSCksDQoJCQkJICAgIHBkYXRhLT5uYW1lKTsNCg0KQmVzdCByZWdhcmRzLA0KSmluZ29vIEhh
bg0KDQo+ICsJaWYgKHJldCA8IDApIHsNCj4gKwkJZGV2X2VycigmcGRldi0+ZGV2LCAidW5hYmxl
IHRvIHJlcXVlc3QgR1BJT1xuIik7DQo+ICsJCXJldHVybiByZXQ7DQo+ICsJfQ0KPiArDQo+ICsJ
bWVtc2V0KCZwcm9wcywgMCwgc2l6ZW9mKHByb3BzKSk7DQo+ICsJcHJvcHMudHlwZSA9IEJBQ0tM
SUdIVF9SQVc7DQo+ICsJcHJvcHMubWF4X2JyaWdodG5lc3MgPSAxOw0KPiArCWJsID0gYmFja2xp
Z2h0X2RldmljZV9yZWdpc3RlcihkZXZfbmFtZSgmcGRldi0+ZGV2KSwgJnBkZXYtPmRldiwgZ2Js
LA0KPiArCQkJCSAgICAgICAmZ3Bpb19iYWNrbGlnaHRfb3BzLCAmcHJvcHMpOw0KPiArCWlmIChJ
U19FUlIoYmwpKSB7DQo+ICsJCWRldl9lcnIoJnBkZXYtPmRldiwgImZhaWxlZCB0byByZWdpc3Rl
ciBiYWNrbGlnaHRcbiIpOw0KPiArCQlyZXR1cm4gUFRSX0VSUihibCk7DQo+ICsJfQ0KPiArDQo+
ICsJYmwtPnByb3BzLmJyaWdodG5lc3MgPSBwZGF0YS0+ZGVmX3ZhbHVlOw0KPiArCWJhY2tsaWdo
dF91cGRhdGVfc3RhdHVzKGJsKTsNCj4gKw0KPiArCXBsYXRmb3JtX3NldF9kcnZkYXRhKHBkZXYs
IGJsKTsNCj4gKwlyZXR1cm4gMDsNCj4gK30NCg0KDQo

Hi Jingoo,

On Tuesday 27 November 2012 01:10:36 Jingoo Han wrote:

On Saturday, November 24, 2012 1:35 AM, Laurent Pinchart wrote

quoted

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---

 drivers/video/backlight/Kconfig          |    7 ++
 drivers/video/backlight/Makefile         |    1 +
 drivers/video/backlight/gpio_backlight.c |  158 +++++++++++++++++++++++++
 include/video/gpio_backlight.h           |   21 ++++
 4 files changed, 187 insertions(+), 0 deletions(-)
 create mode 100644 drivers/video/backlight/gpio_backlight.c
 create mode 100644 include/video/gpio_backlight.h

[...]

quoted

+static int __devinit gpio_backlight_probe(struct platform_device *pdev)
+{
+	struct gpio_backlight_platform_data *pdata = pdev->dev.platform_data;
+	struct backlight_properties props;
+	struct backlight_device *bl;
+	struct gpio_backlight *gbl;
+	int ret;
+
+	gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+	if (gbl = NULL)
+		return -ENOMEM;
+
+	gbl->dev = &pdev->dev;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "failed to find platform data\n");
+		return -ENODEV;
+	}
+
+	gbl->fbdev = pdata->fbdev;
+	gbl->gpio = pdata->gpio;
+	gbl->active = pdata->active_low ? 0 : 1;
+
+	ret = devm_gpio_request_one(gbl->dev, gbl->gpio, GPIOF_DIR_OUT,
+				    pdata->name);

Please use GPIOF_INIT flags if you want to turn off GPIO backlight.
If gbl->active is inverted, GPIOF_INIT_HIGH can be used as below:

	ret = devm_gpio_request_one(gbl->dev, gbl->gpio,
				    GPIOF_DIR_OUT | (gbl->active ?
				    GPIOF_INIT_LOW : GPIOF_INIT_HIGH),
				    pdata->name);

Good point, thank you. I'll fix that.

quoted

+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to request GPIO\n");
+		return ret;
+	}
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = 1;
+	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, gbl,
+				       &gpio_backlight_ops, &props);
+	if (IS_ERR(bl)) {
+		dev_err(&pdev->dev, "failed to register backlight\n");
+		return PTR_ERR(bl);
+	}
+
+	bl->props.brightness = pdata->def_value;
+	backlight_update_status(bl);
+
+	platform_set_drvdata(pdev, bl);
+	return 0;
+}

-- 
Regards,

Laurent Pinchart