Commit ef9d7938 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Sam Ravnborg
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video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display() 



Simplify the nested loops to handle conversion from linear frame buffer
to ssd1307 page layout:
  1. Move last page handling one level up, as the value of "m" is the
     same inside a page,
  2. array->data[] is filled linearly, so there is no need to
     recalculate array_idx over and over again; a simple increment is
     sufficient.

Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: default avatarSam Ravnborg <sam@ravnborg.org>
Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210727134730.3765898-3-geert@linux-m68k.org
parent 7b4b3733

drivers/video/fbdev/ssd1307fb.c

+10 −7
Original line number Diff line number Diff line
@@ -158,6 +158,7 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par) 
	u8 *vmem = par->info->screen_buffer;

	unsigned int line_length = par->info->fix.line_length;

	unsigned int pages = DIV_ROUND_UP(par->height, 8);

	u32 array_idx = 0;

	int ret, i, j, k;



	array = ssd1307fb_alloc_array(par->width * pages, SSD1307FB_DATA);
@@ -194,19 +195,21 @@ static int ssd1307fb_update_display(struct ssd1307fb_par *par) 
	 */



	for (i = 0; i < pages; i++) {

		for (j = 0; j < par->width; j++) {

		int m = 8;

			u32 array_idx = i * par->width + j;

			array->data[array_idx] = 0;



		/* Last page may be partial */

		if (i + 1 == pages && par->height % 8)

			m = par->height % 8;

		for (j = 0; j < par->width; j++) {

			u8 data = 0;



			for (k = 0; k < m; k++) {

				u8 byte = vmem[(8 * i + k) * line_length +

					       j / 8];

				u8 bit = (byte >> (j % 8)) & 1;

				array->data[array_idx] |= bit << k;

				data |= bit << k;

			}

			array->data[array_idx++] = data;

		}

	}