media: bcm2835-unicam: Disable trigger mode operation

The imx219/imx708 sensors frequently generate a single corrupt frame
(image or embedded data) when the sensor first starts. This can either
be a missing line, or invalid samples within the line. This only occurrs
using the upstream Unicam kernel driver.

Disabling trigger mode elimiates this corruption. Since trigger mode is
a legacy feature copied from the firmware driver and not expected to be
needed, remove it. Tested on the Raspberry Pi cameras and shows no ill
effects.

Signed-off-by: Naushir Patuck <[e-mail]>
Reviewed-by: Jacopo Mondi <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/broadcom/bcm2835-unicam.c

···
 		}
 	}
 
-	if (unicam_reg_read(unicam, UNICAM_ICTL) & UNICAM_FCM) {
-		/* Switch out of trigger mode if selected */
-		unicam_reg_write_field(unicam, UNICAM_ICTL, 1, UNICAM_TFC);
-		unicam_reg_write_field(unicam, UNICAM_ICTL, 0, UNICAM_FCM);
-	}
 	return IRQ_HANDLED;
 }
 
···
 
 	unicam_reg_write_field(unicam, UNICAM_ANA, 0, UNICAM_DDL);
 
-	/* Always start in trigger frame capture mode (UNICAM_FCM set) */
-	val = UNICAM_FSIE | UNICAM_FEIE | UNICAM_FCM | UNICAM_IBOB;
+	val = UNICAM_FSIE | UNICAM_FEIE | UNICAM_IBOB;
 	line_int_freq = max(fmt->height >> 2, 128);
 	unicam_set_field(&val, line_int_freq, UNICAM_LCIE_MASK);
 	unicam_reg_write(unicam, UNICAM_ICTL, val);