Hello Thomas Niederprüm,
The patch a3998fe03e87: "fbdev: ssd1307fb: Unify init code and obtain
hw specific bits from DT" from Mar 31, 2015, leads to the following
static checker warning:
drivers/video/fbdev/ssd1307fb.c:371 ssd1307fb_init()
warn: add some parenthesis here?
drivers/video/fbdev/ssd1307fb.c
366 /* Set COM pins configuration */
367 ret = ssd1307fb_write_cmd(par->client, SSD1307FB_SET_COM_PINS_CONFIG);
368 if (ret < 0)
369 return ret;
370
371 compins = 0x02 | (!par->com_seq & 0x1) << 4
372 | (par->com_lrremap & 0x1) << 5;
Smatch is complaining because it's normally "!par->com_seq & 0x1" is
a bug and "!(par->com_seq & 0x1)" is intended. I don't know what was
intended here though. If the current code is correct, you can silence
the static checker warning by writing it as "(!par->com_seq) & 0x1".
But I also have a hard time remembering if | or << is higher precedence
so that might be clearer with parenthesis as well even though the code
is clearly correct when I google for "order of operations" in C.
373 ret = ssd1307fb_write_cmd(par->client, compins);
374 if (ret < 0)
375 return ret;
regards,
dan carpenter