Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: pQHfuea1n6HvBzLnXY4q2xY5gL5e2sVLtU/XkIjxJXH5IWwVumJOUTKrqIA4G48+f0LYa3v0/N
 j1O+74QXzZ4BWFHn7fdcWoQBndpZAWNvdleLQwWVktbIRErYMkB3chhmeQGT5oYpk/z8rTXr34
 ea5j/qt0GGRdHGZ1j51UXtf9Tmx8kG/30/qqSYLzUN9J+GsKvpv4idcEKe6Z7I9wXNWCD3+LOm
 T4sR+Y5gjQtpi2VNltRGTo3dp5mFWf0zSyDe9Mh63RxHnW4Kuzni2G/Bj45jdqYTG/POrBDRst
 c/pzKP+Rd+GTzkMdKxxqGoVD
From:   Eugen Hristev <eugen.hristev@microchip.com>
To:     <linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
CC:     <jacopo@jmondi.org>, <laurent.pinchart@ideasonboard.com>,
        <sakari.ailus@iki.fi>, <robh+dt@kernel.org>,
        <nicolas.ferre@microchip.com>,
        Eugen Hristev <eugen.hristev@microchip.com>
Subject: [PATCH 21/21] media: atmel: atmel-isc-base: clamp wb gain coefficients
Date:   Fri, 22 Oct 2021 10:52:47 +0300
Message-ID: <20211022075247.518880-22-eugen.hristev@microchip.com>
In-Reply-To: <20211022075247.518880-1-eugen.hristev@microchip.com>
References: <20211022075247.518880-1-eugen.hristev@microchip.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
Precedence: bulk

White balance computed gains can overflow above the 13 bits hardware
coefficient that can be used, in some specific scenarios like a subexposure
from the sensor when the image is mostly black.
In this case the computed gain has to be clamped to the maximum value
allowed by the hardware.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
 drivers/media/platform/atmel/atmel-isc-base.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
index 071ac5eec7ec..53141de78f67 100644
--- a/drivers/media/platform/atmel/atmel-isc-base.c
+++ b/drivers/media/platform/atmel/atmel-isc-base.c
@@ -1416,6 +1416,10 @@ static void isc_wb_update(struct isc_ctrls *ctrls)
 		/* multiply both gains and adjust for decimals */
 		ctrls->gain[c] = s_gain[c] * gw_gain[c];
 		ctrls->gain[c] >>= 9;
+
+		/* make sure we are not out of range */
+		ctrls->gain[c] = clamp_val(ctrls->gain[c], 0, GENMASK(12, 0));
+
 		v4l2_dbg(1, debug, &isc->v4l2_dev,
 			 "isc wb: component %d, final gain %u\n",
 			 c, ctrls->gain[c]);
-- 
2.25.1