drm/tilcdc: LCD panels clocks initialization and earlier backlight initialization

[Hiremath, Vaibhav]

> -----Original Message-----
> From: devicetree-discuss [mailto:devicetree-discuss-
> bounces+hvaibhav=ti.com at lists.ozlabs.org] On Behalf Of Michal Bachraty
> Sent: Thursday, March 28, 2013 11:02 PM
> To: dri-devel at lists.freedesktop.org; devicetree-
> discuss at lists.ozlabs.org
> Cc: robdclark at gmail.com; koen at dominion.thruhere.net
> Subject: drm/tilcdc: LCD panels clocks initialization and earlier
> backlight initialization
> 
> Hi,
> 
> I'm trying to use tilcdc driver for KWH050TG08 LCD panel connected to
> AM335x
> processor (3.9 rc1 kernel). I have prepared DT bindings for that
> (listed
> bellow). I see fb0 device but I have no clocks going from cpu to LCD.
> My
> clocks for LCD seems not properly to be set ...
> 
> virt_25000000_ck               1           1            25000000
>     sys_clkin_ck                8           19           25000000
>        dpll_disp_ck             0           1            25000000
>           dpll_disp_m2_ck       0           1            25000000
>              lcd_gclk           0           1            25000000
> 
> and tilcdc_crtc is not called. I also set lcd_gclk to 300MHz, but I got
> same
> result. The question is there any way how to properly set clocks for
> LCD?
> 
Not sure  about the LCDC DRM driver, but I just tested clk_set_rate()
For lcdc_gclk clock and it is working for me. I could able to set
300MHz freq on my BeagleBone platform, with below code -


diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
index e54a480..443fb26 100644
--- a/arch/arm/mach-omap2/board-generic.c
+++ b/arch/arm/mach-omap2/board-generic.c
@@ -11,6 +11,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include <linux/clk-private.h>
 #include <linux/io.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
@@ -37,6 +38,8 @@ static struct of_device_id omap_dt_match_table[] __initdata = {

 static void __init omap_generic_init(void)
 {
+       struct clk *clk;
+
        omap_sdrc_init(NULL, NULL);

        of_platform_populate(NULL, omap_dt_match_table, NULL, NULL);
@@ -49,6 +52,15 @@ static void __init omap_generic_init(void)
                omap4_panda_display_init_of();
        else if (of_machine_is_compatible("ti,omap4-sdp"))
                omap_4430sdp_display_init_of();
+
+       clk = clk_get(NULL, "lcd_gclk");
+       if (IS_ERR(clk))
+               printk("Can not get lcd_gclk clock\n");
+
+       printk("%s:%d gclk_rate - %lu\n", __func__, __LINE__, clk_get_rate(clk));
+       clk_set_rate(clk, 300000000);
+       printk("%s:%d clk_rate - %lu\n", __func__, __LINE__, clk_get_rate(clk));
+       clk_put(clk);
 }

 #ifdef CONFIG_SOC_OMAP2420


Thanks,
Vaibhav