[PATCH v1 3/5] drivers: media: bcm2835-unicam: Disable trigger mode operation

[Naushir Patuck <naush@raspberrypi.com>]

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>
---
 drivers/media/platform/broadcom/bcm2835-unicam.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c b/drivers/media/platform/broadcom/bcm2835-unicam.c
index d573d4d89881..550eb1b064f1 100644
--- a/drivers/media/platform/broadcom/bcm2835-unicam.c
+++ b/drivers/media/platform/broadcom/bcm2835-unicam.c
@@ -834,11 +834,6 @@ 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;
 }
 
@@ -1002,8 +997,7 @@ 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);
-- 
2.34.1