-vis On S3c2410x Delta Driver - — Quick & Popular

if (change_type == VIS_CHANGE_BACKLIGHT) 
    // No delta calc needed - direct PWM write
    s3c2410x_set_backlight(new->brightness);
    return;

Traditional framebuffer drivers redraw entire sections or use double-buffering with memcpy. The S3c2410x lacks an LCD DMA engine sophisticated enough for partial screen updates without tearing.

The -vis delta driver solves this by hooking the s3c2410fb_set_par() and s3c2410fb_pan_display() calls. It maintains a shadow framebuffer in non-cached memory. On each vis_update_region(x,y,w,h) call: -vis On S3c2410x Delta Driver -

Because the LCD controller can read from Steppingstone without stalling the CPU’s ARM920T core, updates happen in the background. if (change_type == VIS_CHANGE_BACKLIGHT) // No delta calc

Understanding the internal state ("visibility") of the Delta Driver is crucial for troubleshooting. Because the LCD controller can read from Steppingstone