diff options
| author | Maxime Ripard <maxime.ripard@free-electrons.com> | 2013-04-22 12:02:24 +0200 |
|---|---|---|
| committer | Tomi Valkeinen <tomi.valkeinen@ti.com> | 2013-05-28 14:41:58 +0300 |
| commit | 3394e645a88c722396fc1b03c31a3ffc158744ad (patch) | |
| tree | 46855f8b010a676d7d659e6f206599f971fc6605 | |
| parent | 9f7714d4638382d5f84fefd322983925935da742 (diff) | |
| download | linux-3394e645a88c722396fc1b03c31a3ffc158744ad.tar.bz2 | |
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>
| -rw-r--r-- | drivers/video/ssd1307fb.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/video/ssd1307fb.c b/drivers/video/ssd1307fb.c index 9daf058917a7..04a435886855 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); } } |