summaryrefslogtreecommitdiffstats
path: root/drivers/video/ssd1307fb.c
diff options
context:
space:
mode:
authorMaxime Ripard <maxime.ripard@free-electrons.com>2013-04-22 12:02:24 +0200
committerTomi Valkeinen <tomi.valkeinen@ti.com>2013-05-28 14:41:58 +0300
commit3394e645a88c722396fc1b03c31a3ffc158744ad (patch)
tree46855f8b010a676d7d659e6f206599f971fc6605 /drivers/video/ssd1307fb.c
parent9f7714d4638382d5f84fefd322983925935da742 (diff)
video: ssd1307fb: Speed up the communication with the controller
The code until now was sending only 1pixel-wide page segment at once, and started a new transfer every time. It has proven very inefficient, because for one byte to display on the screen, we had to actually send 3 bytes over I2C: the address, the type of data that was going to the controller, and then the actual data. This patches changes that by sending a whole page at once, avoiding most of this expensive overhead. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Diffstat (limited to 'drivers/video/ssd1307fb.c')
-rw-r--r--drivers/video/ssd1307fb.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/video/ssd1307fb.c b/drivers/video/ssd1307fb.c
index 9daf058917a..04a43588685 100644
--- a/drivers/video/ssd1307fb.c
+++ b/drivers/video/ssd1307fb.c
@@ -168,23 +168,28 @@ static void ssd1307fb_update_display(struct ssd1307fb_par *par)
*/
for (i = 0; i < (par->height / 8); i++) {
+ struct ssd1307fb_array *array;
ssd1307fb_write_cmd(par->client,
SSD1307FB_START_PAGE_ADDRESS + i + par->page_offset);
ssd1307fb_write_cmd(par->client, 0x00);
ssd1307fb_write_cmd(par->client, 0x10);
+ array = ssd1307fb_alloc_array(par->width, SSD1307FB_DATA);
+
for (j = 0; j < par->width; j++) {
- u8 buf = 0;
+ array->data[j] = 0;
for (k = 0; k < 8; k++) {
u32 page_length = par->width * i;
u32 index = page_length + (par->width * k + j) / 8;
u8 byte = *(vmem + index);
u8 bit = byte & (1 << (j % 8));
bit = bit >> (j % 8);
- buf |= bit << k;
+ array->data[j] |= bit << k;
}
- ssd1307fb_write_data(par->client, buf);
}
+
+ ssd1307fb_write_array(par->client, array, par->width);
+ kfree(array);
}
}