media: bcm2835-unicam: Disable trigger mode operation

BugLink: https://bugs.launchpad.net/bugs/2104873

[ Upstream commit 697a252 ]

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 <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

Author: naushir

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

@@ -816,11 +816,6 @@ static irqreturn_t unicam_isr(int irq, void *dev)
 		}
 	}
 
-	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;
 }
 
@@ -984,8 +979,7 @@ static void unicam_start_rx(struct unicam_device *unicam,
 
 	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);