RE: Suspend/Resume support with Omap2fb

[Tomi Valkeinen <tomi.valkeinen@nokia.com>]

Hi,

On Thu, 2009-03-12 at 19:26 +0100, ext Hiremath, Vaibhav wrote:
> Hi,
> 
> Finally I could able to find the root-cause, actually some of the previous observations miss-led me to dig into power management, suspend/resume path and clock structure. But after bit debugging and with the help of Sanjeev, we got the rid of it.
> 
> The issue is with DSS2 library, inside function "dpi_display_suspend". It calls dispc_enable_lcd_out(0), but doesn't wait till the frame-done interrupt. And due to this I was getting some abrupt behavior in suspend/resume path. 
> Actually in the beginning I overlooked legacy frame-buffer driver, which handles this scenario perfectly.

dispc_enable_lcd_out(0) waits for FRAMEDONE. Please use the latest DSS2
version from my git repository =).

 Tomi

>  
> For Display sub-system we have 2 interface clocks coming, L3_ICLK and L4_ICLK. Out of these, L4_ICLK goes to Display register access and L3_ICLK goes to DMA register. In our suspend call we are disabling clocks for L3_ICLK (we don't control L4_ICLK), and due to this L4_ICLK stays attached with GFX. You will only be able to find out this by looking to CM_CLKSTST_DSS.CLKACTIVITY_DSS, which is set 1 and indicates some interface clock is still active in DSS domain.
> 
> Below is the patch which will explain the change 
> 
> 
> +#include <linux/completion.h>
> +#include <linux/jiffies.h>
> 
> +static void dpi_display_isr(void *arg, unsigned int irqstatus)
> +{
> +       struct omap_display *display = (struct omap_display *)arg;
> +
> +       complete(&display->frame_done);
> +}
> 
> static int dpi_display_suspend(struct omap_display *display)
>  {
> +       void *handle = NULL;
> +
>         if (display->state != OMAP_DSS_DISPLAY_ACTIVE)
>                 return -EINVAL;
> 
>         if (display->panel->suspend)
>                 display->panel->suspend(display);
> 
> +       /*
> +        * Wait for frame done interrupt
> +        */
> +       handle = omap_dispc_register_isr(dpi_display_isr, display,
> +                       DISPC_IRQ_FRAMEDONE);
> +       if (!handle)
> +               return -EINVAL;
> +
> +       init_completion(&display->frame_done);
> +
>         dispc_enable_lcd_out(0);
> +       if (!wait_for_completion_timeout(&display->frame_done,
> +                               msecs_to_jiffies(500))) {
> +               printk("timeout waiting for FRAME DONE\n");
> +       }
> 
> Still I need to test this thoroughly, I may hit some another issue (Already I am seeing some crashes also when off state is enabled). I will create consolidated patch for this and will submit to list.
> 
> Thanks,
> Vaibhav Hiremath