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 <[email protected]> --- drivers/video/ssd1307fb.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/video/ssd1307fb.c b/drivers/video/ssd1307fb.c index 35f5348..cab5f7c 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); } } -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
