-vis On S3c2410x Delta Driver -

if (delta->dirty_mask & DIRTY_LCDCON2) writel(delta->lcdcon2_shadow, &hw->lcdcon2);

struct vis_device *vis = info->par; struct vis_display_settings new_mode; // Convert fb_var_screeninfo to VIS structure vis_fb_var_to_settings(&info->var, &new_mode);

// Optimization hints bool vsync_locked; // Are we within VBI? int pending_changes; ; The vis_calc_delta() function is invoked when a user-space application (via ioctl ) or the kernel (via fb_blank ) requests a change. It mutates only the necessary registers. -vis On S3c2410x Delta Driver -

// Step 2: Check horizontal/vertical timings (HBP, VBP) if (new->xres != delta->current_mode.xres

The term refers to a specific architectural pattern where the vis subsystem manages a Delta Driver . In software engineering, a "Delta Driver" is a driver that does not re-initialize the entire hardware stack on every change but rather computes the difference (delta) between the current hardware state and the requested state, applying only incremental changes. // Step 2: Check horizontal/vertical timings (HBP, VBP)

struct vis_s3c_delta_state *delta = &vis->delta; struct s3c2410x_lcd *hw = vis->hw_regs; unsigned long flags; // Sync with VSYNC to avoid tearing spin_lock_irqsave(&vis->lock, flags);

1. Introduction: The Embedded Video Challenge The Samsung S3C2410X, based on the ARM920T core, was a revolutionary System-on-Chip (SoC) for its time. Widely used in PDAs, automotive telematics, and early Linux-based handhelds (like the Sharp Zaurus), it featured an integrated LCD Controller (LCDC). However, driving complex displays efficiently required more than just a framebuffer; it required a robust Video Interface System (VIS) . dirty_mask = 0

// Clear dirty mask - delta applied delta->dirty_mask = 0; delta->current_mode = delta->pending_mode;