Re: [PATCH] atmel_lcdfb: backlight control
From: Haavard Skinnemoen <hidden>
Date: 2008-01-23 17:33:37
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On Fri, 18 Jan 2008 15:44:35 +0100 Nicolas Ferre [off-list ref] wrote:
From: David Brownell <redacted> On the sam9 EK boards, the LCD backlight is hooked up to a PWM output from the LCD controller. It's controlled by "contrast" registers though. This patch lets boards declare that they have that kind of backlight control. The driver can then export this control, letting screenblank and other operations actually take effect ... reducing the typically substantial power drain from the backlight. Signed-off-by: David Brownell <redacted> Signed-off-by: Nicolas Ferre <redacted>
Looks good to me. It won't affect any current AVR32 boards, although that may change in the future. A couple of minor comments below.
+static struct backlight_ops atmel_lcdc_bl_ops = {
+ .update_status = atmel_bl_update_status,
+ .get_brightness = atmel_bl_get_brightness,
+};This can be const, no? No it can't, since backlight_device_register() takes a non-const pointer for some reason...
+#else
+
+static inline void init_backlight(struct atmel_lcdfb_info *sinfo)
+{
+ dev_warn(&sinfo->pdev->dev, "backlight control is not available\n");
+}
+
+static inline void exit_contrast(struct atmel_lcdfb_info *sinfo)
+{
+}
+
+#endifThis looks a bit asymmetric...
quoted hunk ↗ jump to hunk
+static inline void init_contrast(struct atmel_lcdfb_info *sinfo) +{ + /* have some default contrast/backlight settings */ + lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, contrast_ctr); + lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_VAL, ATMEL_LCDC_CVAL_DEFAULT); + + if (sinfo->lcdcon_is_backlight) + init_backlight(sinfo); +} + static struct fb_fix_screeninfo atmel_lcdfb_fix __initdata = { .type = FB_TYPE_PACKED_PIXELS,@@ -370,10 +472,6 @@ static int atmel_lcdfb_set_par(struct fb /* Disable all interrupts */ lcdc_writel(sinfo, ATMEL_LCDC_IDR, ~0UL); - /* Set contrast */ - value = ATMEL_LCDC_PS_DIV8 | ATMEL_LCDC_POL_POSITIVE | ATMEL_LCDC_ENA_PWMENABLE; - lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, value); - lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_VAL, ATMEL_LCDC_CVAL_DEFAULT); /* ...wait for DMA engine to become idle... */ while (lcdc_readl(sinfo, ATMEL_LCDC_DMACON) & ATMEL_LCDC_DMABUSY) msleep(10);@@ -577,6 +675,7 @@ static int __init atmel_lcdfb_probe(stru sinfo->default_monspecs = pdata_sinfo->default_monspecs; sinfo->atmel_lcdfb_power_control = pdata_sinfo->atmel_lcdfb_power_control; sinfo->guard_time = pdata_sinfo->guard_time; + sinfo->lcdcon_is_backlight = pdata_sinfo->lcdcon_is_backlight; } else { dev_err(dev, "cannot get default configuration\n"); goto free_info;@@ -670,6 +769,9 @@ static int __init atmel_lcdfb_probe(stru goto release_mem; } + /* Initialize PWM for contrast or backlight ("off") */ + init_contrast(sinfo); + /* interrupt */ ret = request_irq(sinfo->irq_base, atmel_lcdfb_interrupt, 0, pdev->name, info); if (ret) {@@ -755,6 +857,7 @@ static int __exit atmel_lcdfb_remove(str if (!sinfo) return 0; + exit_contrast(sinfo);
Missing exit_contrast() in probe() error path? Haavard ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/