better handling of screen backbuffers

Author: Vincent-FK

drivers/staging/fbtft/fbtft-bus.c

@@ -124,7 +124,7 @@ int fbtft_start_new_screen_transfer_async(struct fbtft_par *par)
 	lock = true;
 
 	/* Debug fps */
-#define FPS_DEBUG
+//#define FPS_DEBUG
 #ifdef FPS_DEBUG
 	long fps;
 	ktime_t ts_now = ktime_get();
@@ -156,17 +156,6 @@ int fbtft_start_new_screen_transfer_async(struct fbtft_par *par)
 
 #endif //FPS_DEBUG
 
-	/* Get last memory buffer not written */
-	if(par->nb_backbuffers_full > 0){
-		par->vmem_ptr = par->vmem_back_buffers[par->vmem_prev_buf_idx];
-		par->nb_backbuffers_full--;
-		par->nb_backbuffers_full = !!par->nb_backbuffers_full; //back to 1 or 0 to avoid overflows
-	}
-	else{
-		par->nb_backbuffers_full = 0; // Avoid overflows, should not happen
-		par->vmem_ptr = par->info->screen_buffer;
-	}
-
 	/* Post process screen for doufle buf copy, notifs, rotation soft... */
 	fbtft_post_process_screen(par);
 

drivers/staging/fbtft/fbtft-core.c

@@ -578,6 +578,15 @@ void fbtft_post_process_screen(struct fbtft_par *par)
 		screen_post_process = true;
 	}
 
+	/* Get last memory buffer not written */
+	if(par->nb_backbuffers_full > 0){
+		par->vmem_ptr = par->vmem_back_buffers[par->vmem_prev_buf_idx];
+		par->nb_backbuffers_full--;
+	}
+	else{
+		par->vmem_ptr = par->info->screen_buffer;
+		par->nb_backbuffers_full = 0; // Avoid overflows, should not happen anyway
+	}
 	//par->vmem_ptr = par->vmem_back_buffers[par->vmem_prev_buf_idx];
 	//par->vmem_ptr = par->info->screen_buffer;
 
@@ -645,7 +654,8 @@ void fbtft_flip_backbuffer(struct fbtft_par *par)
 		par->vmem_size);
 	par->vmem_prev_buf_idx = par->vmem_cur_buf_idx;
 	par->vmem_cur_buf_idx = (par->vmem_cur_buf_idx+1)%FBTFT_VMEM_BUFS;
-	par->nb_backbuffers_full++;
+	if(par->nb_backbuffers_full < FBTFT_VMEM_BUFS)
+		par->nb_backbuffers_full++;
 	//spin_unlock(&par->dirty_lock);
 }
 
@@ -1709,18 +1719,15 @@ static irqreturn_t irq_TE_handler(int irq_no, void *dev_id)
 	if(!pdata->par->ready_for_spi_async)
 		return IRQ_HANDLED;
 
+	/* This should be enabled otherwise there will be some 
+	soft tearing if the userspace flip speed is lower than 
+	TE's IRQ speed. Why? because if we don't wxit now, we'll 
+	display the frambeffer instead of the saved backed buffers*/
 #if 0
-	if (pdata->par->nb_backbuffers_full <= 0)
+	if (pdata->par->nb_backbuffers_full <= 0){
+		pdata->par->nb_backbuffers_full = 0;
 		return IRQ_HANDLED;
-	/*static int prev_must_render = 0;
-	if (prev_must_render == pdata->par->nb_backbuffers_full);
-		return IRQ_HANDLED;*/
-
-	pdata->par->nb_backbuffers_full--;
-	if(pdata->par->nb_backbuffers_full > 1024){
-		pdata->par->nb_backbuffers_full=1;
 	}
-	prev_must_render = pdata->par->nb_backbuffers_full;
 #endif
 
 	fbtft_start_new_screen_transfer_async(pdata->par);

drivers/video/fbdev/core/fbmem.c

@@ -32,6 +32,7 @@
 #include <linux/device.h>
 #include <linux/efi.h>
 #include <linux/fb.h>
+#include <linux/fbtft.h>
 #include <linux/fbcon.h>
 #include <linux/mem_encrypt.h>
 
@@ -1147,6 +1148,7 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
 		ret = fb_cmap_to_user(&cmap_from, &cmap);
 		break;
 	case FBIOPAN_DISPLAY:
+
 		if (copy_from_user(&var, argp, sizeof(var)))
 			return -EFAULT;
 		console_lock();
@@ -1155,6 +1157,10 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
 			return -ENODEV;
 		}
 		ret = fb_pan_display(info, &var);
+
+		/** fbtft switch buffer */
+		fbtft_flip_backbuffer(info->par);
+		
 		unlock_fb_info(info);
 		console_unlock();
 		if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))