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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Maxime Ripard <mripard@kernel.org>
Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH resend 2/5] video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display()
Date: Wed, 14 Jul 2021 16:58:01 +0200	[thread overview]
Message-ID: <20210714145804.2530727-3-geert@linux-m68k.org> (raw)
In-Reply-To: <20210714145804.2530727-1-geert@linux-m68k.org>

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: Geert Uytterhoeven <geert@linux-m68k.org>
---
 drivers/video/fbdev/ssd1307fb.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index e6b6263e3bef847f..6d7bd025bca1a175 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -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++) {
+		int m = 8;
+
+		/* Last page may be partial */
+		if (i + 1 == pages && par->height % 8)
+			m = par->height % 8;
 		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;
+			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;
 		}
 	}
 
-- 
2.25.1


  parent reply	other threads:[~2021-07-14 14:58 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 14:57 [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 1/5] video: fbdev: ssd1307fb: Propagate errors via ssd1307fb_update_display() Geert Uytterhoeven
2021-07-14 14:58 ` Geert Uytterhoeven [this message]
     [not found]   ` <YPXM8AXNje7GXf+i@ravnborg.org>
2021-07-20  7:43     ` [PATCH resend 2/5] video: fbdev: ssd1307fb: Simplify ssd1307fb_update_display() Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 3/5] video: fbdev: ssd1307fb: Extract ssd1307fb_set_address_range() Geert Uytterhoeven
     [not found]   ` <YPXNdJNpYoPSpxSb@ravnborg.org>
2021-07-20  7:51     ` Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 4/5] video: fbdev: ssd1307fb: Optimize screen updates Geert Uytterhoeven
     [not found]   ` <YPXQnlpWUa1QaZKd@ravnborg.org>
2021-07-20  7:56     ` Geert Uytterhoeven
2021-07-20  9:16       ` Geert Uytterhoeven
2021-07-14 14:58 ` [PATCH resend 5/5] video: fbdev: ssd1307fb: Cache address ranges Geert Uytterhoeven
     [not found] ` <YO8CT+Hcw1wfhnH5@ravnborg.org>
2021-07-15  6:54   ` [PATCH resend 0/5] video: fbdev: ssd1307fb: Optimizations and improvements Geert Uytterhoeven
2021-07-20 14:53     ` Daniel Vetter
     [not found] ` <YPXRMXQxCW+Agaz8@ravnborg.org>
2021-07-20  7:33   ` Geert Uytterhoeven

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