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

On Mon, Apr 1, 2013 at 7:31 AM, Hiremath, Vaibhav hvaibhav@ti.com wrote:

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-----Original Message----- From: devicetree-discuss [mailto:devicetree-discuss- bounces+hvaibhav=ti.com@lists.ozlabs.org] On Behalf Of Michal Bachraty Sent: Thursday, March 28, 2013 11:02 PM To: dri-devel@lists.freedesktop.org; devicetree- discuss@lists.ozlabs.org Cc: robdclark@gmail.com; koen@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 -

fwiw, tilcdc drm driver won't set clocks until you do modeset, as it is setting them based on the requested pixel clock. As opposed to setting it once at boot time.

Michal, you may want to add 'drm.debug=7' in your bootargs, and send the bootlog. That should set some light about whether it is even trying to modeset but failing, or some other issue.

BR, -R

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