RE: [Linux-fbdev-devel] [PATCH] added S6E63M0 AMOLED LCD Panel driver.

H Hartley Sweeten
2010-03-30T23:26:20Z

On Tuesday, March 30, 2010 4:03 PM, Andrew Morton wrote:
> On Fri, 26 Mar 2010 12:24:24 +0900
> InKi Dae <daeinki@gmail.com> wrote:
>
>> +static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
>> +{
>> + int ret;
>> +
>> + ret = s6e63m0_panel_send_sequence(lcd, SEQ_PANEL_CONDITION_SET);
>> + ret |= s6e63m0_panel_send_sequence(lcd, SEQ_DISPLAY_CONDITION_SET);
>> + ret |= s6e63m0_panel_send_sequence(lcd, SEQ_GAMMA_SETTING);
>> + ret |= s6e63m0_panel_send_sequence(lcd, SEQ_ETC_CONDITION_SET);
>> + ret |= s6e63m0_panel_send_sequence(lcd, SEQ_ACL_ON);
>> + ret |= s6e63m0_panel_send_sequence(lcd, SEQ_ELVSS_ON);
>> +
>> + return ret;
>> +}
>
> Well. If one call to s6e63m0_panel_send_sequence() returns -ENOMEM and
> another call returns -EIO (for example), this function will return some
> other, incorrect errno.
>
> Which is a rather minor problem, unless some caller is explicitly
> looking for some particular error code, which doesn't happen often.

Why not handle the calls with a loop?

+static int s6e63m0_ldi_init(struct s6e63m0 *lcd)
+{
+ const unsigned short *init_seq[] = {
+ SEQ_PANEL_CONDITION_SET,
+ SEQ_DISPLAY_CONDITION_SET,
+ SEQ_GAMMA_SETTING,
+ SEQ_ETC_CONDITION_SET,
+ SEQ_ACL_ON,
+ SEQ_ELVSS_ON,
+ };
+ int i, ret;
+
+ for (i = 0; i < ARRAY_SIZE(init_seq); i++) {
+ ret = s6e63m0_panel_send_sequence(lcd, init_seq[i]);
+ if (ret)
+ break;
+ }
+ return ret;
+}

Note that _s6e63m0_gamma_ctl has the same issue. Actually, the whole
driver has issues with returning errors properly.

Regards,
Hartley