Access DPCD via NativeAux

i915 is not just a Graphics-Chipset from 2004 it is the graphic-driver-name for the Intel HD Graphic 3000.

So it is should be possible to acces DPCD through an selfwritten Kernel-Module.

Does anyone know if drm_dp_dpcd_write and drm_dp_dpcd_read is maybe already available in sysfs or through SytemIO?

The short answer is, no.

Hey there, I thought now about to write a Kernel Module to access the Display Port Helper Functions. Here is a code snippet:

int ret;
struct drm_dp_aux mydp =
{
    //Init of this struct is missing...
};
ret = drm_dp_aux_register(&mydp);
if ( ret == 0 )
{
    printk(PRIO "Init Successful\n");
    drm_dp_writeb(&mydp, ADDRESS, VALUE);  //ADDRESS and VALUE are user-defined by me
}
else
    printk("PRIO "Error on registration %d\n", ret");
drm_dp_aux_unregister(&mydp);

My Problem is now, that I don't know how to initialize the struc mydp. The Reference in the Link above says that I need the pointer to the struct device that is the parent for this AUX channel. Does anyone know where I can find out the parent?

Thanks alot!

Luke

Hey there!

I figured out a Solution! :-)

I'm gonna try to explain, what I did in short:

I downloaded the actual Linuxkernel (3.16) from kernel.org and edited the intel_dp.c file within the folder drivers/gpu/drm/i915/ to get the Pointer to the Struct in this way:

1. Insert the fallowing lines:

static struct drm_dp_aux *static_dp_aux_ptr;
static struct drm_dp_aux* intel_dp_aux_get_struct(void){
    if (static_dp_aux_ptr == NULL)
        printk(KERN_INFO "Backlight: Could not init the aux_ptr!\n");
    return static_dp_aux_ptr;
}
EXPORT_SYMBOL(intel_dp_aux_get_struct);
static void intel_dp_aux_set_struct(struct drm_dp_aux *dp_aux){
    static_dp_aux_ptr = dp_aux;
}

2. insert this line at the end of the "static void intel_dp_aux_init(...)"-function

intel_dp_aux_set_struct(&intel_dp->aux); //Inserted by Lukas Hofstaetter

Thereby I was able to get the requiered pointer for the Helperfuncitons of drm/drm_dp_helper.h wthin an selfwritten KernelModule.