Hi

Am 01.02.22 um 15:36 schrieb Javier Martinez Canillas:

On 2/1/22 15:05, Geert Uytterhoeven wrote:

quoted

Hi Javier,

On Tue, Feb 1, 2022 at 2:02 PM Javier Martinez Canillas
[off-list ref] wrote:

quoted

On 2/1/22 10:33, Thomas Zimmermann wrote:

quoted

quoted

+{
+    u8 col_end = col_start + cols - 1;
+    int ret;
+
+    if (col_start == ssd1307->col_start && col_end == ssd1307->col_end)
+            return 0;
+
+    ret = ssd1307_write_cmd(ssd1307->client, SSD1307_SET_COL_RANGE);
+    if (ret < 0)
+            return ret;
+
+    ret = ssd1307_write_cmd(ssd1307->client, col_start);
+    if (ret < 0)
+            return ret;
+
+    ret = ssd1307_write_cmd(ssd1307->client, col_end);
+    if (ret < 0)
+            return ret;

Can you write these cmds in one step, such as setting up an array and
sending it with ssd1307_write_array?

I don't think so because the commands are different. But I'll check the
ssd1306 datasheet again to confirma that's the case.

IIRC, I tried that while working on the optimizations for ssd1307fb,
and it didn't work.

That's what I would had expected by reading the datasheet. Thanks a
lot for confirming my assumption.

Thanks to both of you. I was asking because I found the code to be 
repetitive and it's not clear that these 3 statements belong together.

I'd like to suggest to add a function

   ssd1307_write_cmds(client, len, const u8 *cmds)

that loops through cmds and sends the values one by one. A call would 
look like this:

   const u8 set_col_range[] = {
     SSD1307_SET_COL_RANGE,
     col_start,
     col_end
   };

   ssd1307_write_cmds(client, ARRAY_SIZE(set_col_range), set_col_range);

AND/OR

You could have functions that take a command with arguments; either as 
va_args or with one function per number of arguments. Or you could 
combine all these somehow.

Best regards
Thomas

  

Best regards,

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev