I have implemented a basic backlight driver for OMAP3EVM (patch below).
However, have been having few problems. Any suggestions would be useful.
1) Though build was successful; the print from the backlight driver did
not appear during the kernel boot.
2) Figured out that despite defining BACKLIGHT_OMAP3EVM and manually
setting CONFIG_FB_BACKLIGHT=y it gets "reset" during build despite
making these changes:
--- Backlight & LCD device support
<*> Lowlevel LCD controls
< > Samsung LTV350QV LCD Panel
< > Toppoly TDO24M LCD Panels support
< > VGG2432A4 LCM device support
< > Platform LCD controls
-*- Lowlevel Backlight controls
< > Generic (aka Sharp Corgi) Backlight Driver (DEPRECATED)
<*> OMAP3EVM LCD Backlight
3) Was able to overcome this problem with this change:
diff --git a/drivers/video/omap/Kconfig b/drivers/video/omap/Kconfig
@@ -4,6 +4,7 @@ config FB_OMAP
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
+ select FB_BACKLIGHT
help
Frame buffer driver for OMAP based boards.
4) But still, the driver isn't getting loaded.
Is there any further implicit dependency to be satisfied?
Best regards,
Sanjeev
PS: The tabs in the may be replaced with space in the patch below.
Final patch submission will done from Linux machine; will not
have this problem.
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 4a4dd9a..6e4d98a 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -152,6 +152,14 @@ config BACKLIGHT_OMAP1
the PWL module of OMAP1 processors. Say Y if your board
uses this hardware.
+config BACKLIGHT_OMAP3EVM
+ tristate "OMAP3EVM LCD Backlight"
+ depends on BACKLIGHT_CLASS_DEVICE && MACH_OMAP3EVM
+ default y
+ help
+ This driver controls the LCD backlight for OMAP3EVM.
+
config BACKLIGHT_HP680
tristate "HP Jornada 680 Backlight Driver"
depends on BACKLIGHT_CLASS_DEVICE && SH_HP6XX
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 103427d..0150953 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_BACKLIGHT_CORGI) += corgi_bl.o
obj-$(CONFIG_BACKLIGHT_HP680) += hp680_bl.o
obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o
obj-$(CONFIG_BACKLIGHT_OMAP1) += omap1_bl.o
+obj-$(CONFIG_BACKLIGHT_OMAP3EVM) += omap3evm_bl.o
obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o
obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o
obj-$(CONFIG_BACKLIGHT_PWM) += pwm_bl.o
diff --git a/drivers/video/backlight/omap3evm_bl.c b/drivers/video/backlight/omap3evm_bl.c
new file mode 100644
index 0000000..8104834
--- /dev/null
+++ b/drivers/video/backlight/omap3evm_bl.c
@@ -0,0 +1,233 @@
+/*
+ * drivers/video/backlight/omap_bl.c
+ *
+ * Backlight driver for OMAP based boards.
+ *
+ * Copyright (c) 2006 Andrzej Zaborowski <balrog@xxxxxxxxx>
+ *
+ * This package is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This package is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this package; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+
+#include <mach/omapfb.h>
+
+/**
+ * Name of the driver
+ */
+#define OMAPBL_DRVNAME "omap-backlight"
+
+/**
+ * Maximum intensity supported by the panel
+ */
+#define OMAPBL_MAX_INTENSITY 100
+
+/**
+ * Default intensity after boot-up
+ */
+#define OMAPBL_DEF_INTENSITY 70
+
+/**
+ * Flag indicating the driver status - suspended / running
+ */
+#define OMAPBL_SUSPENDED 0x01
+
+/**
+ * Flag indicating low battery
+ */
+#define OMAPBL_BATTLOW 0x02
+
+
+/**
+ * Current backlight intensity
+ */
+static int panel_intensity;
+
+/**
+ * Backlight properties
+ */
+static struct backlight_properties omapbl_props;
+
+/**
+ * Generic backlight information
+ */
+static struct generic_bl_info *omapbl_info;
+
+/**
+ * Backlight device
+ */
+struct backlight_device *omapbl_device;
+
+/**
+ * Backlight flags
+ */
+static unsigned long omapbl_flags;
+
+
+static int omapbl_set_intensity(struct backlight_device *bd)
+{
+ int intensity = bd->props.brightness;
+
+ if (bd->props.power != FB_BLANK_UNBLANK)
+ intensity = 0;
+ if (bd->props.fb_blank != FB_BLANK_UNBLANK)
+ intensity = 0;
+ if (omapbl_flags & OMAPBL_SUSPENDED)
+ intensity = 0;
+ if (omapbl_flags & OMAPBL_BATTLOW)
+ intensity &= omapbl_info->limit_mask;
+
+ omapbl_info->set_bl_intensity(intensity);
+
+ panel_intensity = intensity;
+
+ if (omapbl_info->kick_battery)
+ omapbl_info->kick_battery();
+
+ return 0;
+}
+
+static int omapbl_get_intensity(struct backlight_device *bd)
+{
+ return panel_intensity;
+}
+
+/**
+ * omapbl_limit_intensity - Limit the backlight iuntensity
+ * @limit - Value 0 clears the limit. Else used as limit to be set.
+ *
+ * When the battery is low, this function is called to limit the backlight.
+ */
+void omapbl_limit_intensity(int limit)
+{
+ if (limit)
+ omapbl_flags |= OMAPBL_BATTLOW;
+ else
+ omapbl_flags &= ~OMAPBL_BATTLOW;
+
+ backlight_update_status(omapbl_device);
+}
+EXPORT_SYMBOL(omapbl_limit_intensity);
+
+static struct backlight_ops omapbl_ops = {
+ .get_brightness = omapbl_get_intensity,
+ .update_status = omapbl_set_intensity,
+};
+
+static int omapbl_probe(struct platform_device *pdev)
+{
+ struct generic_bl_info *machinfo = pdev->dev.platform_data;
+ const char *name = OMAPBL_DRVNAME;
+
+ omapbl_info = machinfo;
+ if (!machinfo->limit_mask)
+ machinfo->limit_mask = -1;
+
+ if (machinfo->name)
+ name = machinfo->name;
+
+ omapbl_device = backlight_device_register (name,
+ &pdev->dev, NULL, &omapbl_ops);
+
+ if (IS_ERR (omapbl_device))
+ return PTR_ERR (omapbl_device);
+
+ platform_set_drvdata(pdev, omapbl_device);
+
+ omapbl_device->props.max_brightness = machinfo->max_intensity;
+ omapbl_device->props.power = FB_BLANK_UNBLANK;
+ omapbl_device->props.brightness = machinfo->default_intensity;
+
+ backlight_update_status(omapbl_device);
+
+ printk(KERN_INFO "OMAP LCD backlight initialized.\n");
+
+ return 0;
+}
+
+static int omapbl_remove(struct platform_device *pdev)
+{
+ struct backlight_device *bd = platform_get_drvdata(pdev);
+
+ omapbl_props.power = 0;
+ omapbl_props.brightness = 0;
+ backlight_update_status(bd);
+
+ backlight_device_unregister(bd);
+
+ printk(KERN_INFO "OMAP LCD backlight unloaded.\n");
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int omapbl_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct backlight_device *bd = platform_get_drvdata(pdev);
+
+ omapbl_flags |= OMAPBL_SUSPENDED;
+ backlight_update_status(bd);
+
+ return 0;
+}
+
+static int omapbl_resume(struct platform_device *pdev)
+{
+ struct backlight_device *bd = platform_get_drvdata(pdev);
+
+ omapbl_flags &= ~OMAPBL_SUSPENDED;
+ backlight_update_status(bd);
+
+ return 0;
+}
+#else
+#define omapbl_suspend NULL
+#define omapbl_resume NULL
+#endif
+
+static struct platform_driver omapbl_driver = {
+ .probe = omapbl_probe,
+ .remove = omapbl_remove,
+ .suspend = omapbl_suspend,
+ .resume = omapbl_resume,
+ .driver = {
+ .name = "omap-backlight",
+ },
+};
+
+static int __init omapbl_init(void)
+{
+ return platform_driver_register(&omapbl_driver);
+}
+
+static void __exit omapbl_exit(void)
+{
+ platform_driver_unregister(&omapbl_driver);
+}
+
+module_init(omapbl_init);
+module_exit(omapbl_exit);
+
+MODULE_AUTHOR("Sanjeev Premi <premi@xxxxxx>");
+MODULE_DESCRIPTION("OMAP LCD Backlight driver");
+MODULE_LICENSE("GPLv2");
+
diff --git a/drivers/video/omap/Kconfig b/drivers/video/omap/Kconfig
index c355b59..41ae018 100644
--- a/drivers/video/omap/Kconfig
+++ b/drivers/video/omap/Kconfig
@@ -4,6 +4,7 @@ config FB_OMAP
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
+ select FB_BACKLIGHT
help
Frame buffer driver for OMAP based boards.
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