[PATCH] RKISP1: correct histogram window size

From: "Krzysztof Hałasa" <khalasa@piap.pl>
To: Dafna Hirschfeld <dafna@fastmail.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>,
	linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Jacopo Mondi <jacopo.mondi@ideasonboard.com>,
	Paul Elder <paul.elder@ideasonboard.com>,
	Ondrej Jirman <megi@xff.cz>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Subject: [PATCH] RKISP1: correct histogram window size
Date: Fri, 09 May 2025 09:51:46 +0200	[thread overview]
Message-ID: <m3tt5u9q7h.fsf@t19.piap.pl> (raw)

Without the patch (i.MX8MP, all-white RGGB-12 full HD input from
the sensor, YUV NV12 output from ISP, full range, histogram Y mode).
HIST_STEPSIZE = 3 (lowest permitted):

isp_hist_h_size: 383 (= 1920 / 5 - 1)
isp_hist_v_size: 215 (= 1080 / 5 - 1)
histogram_measurement_result[16]: 0 0 0 0  0 0 0 0  0 0 0 0  0 0 0 229401

Apparently the histogram is missing the last column (3-pixel wide,
though only single pixels count) and the last (same idea) row
of the input image: 1917 * 1077 / 3 / 3 = 229401

with the patch applied:
isp_hist_h_size: 384 (= 1920 / 5)
isp_hist_v_size: 216 (= 1080 / 5)
histogram_measurement_result[16]: 0 0 0 0  0 0 0 0  0 0 0 0  0 0 0 230400

1920 * 1080 / 3 / 3 = 230400

Signed-off-by: Krzysztof Hałasa <khalasa@piap.pl>

diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
index b28f4140c8a3..ca9b3e711e5f 100644
--- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
+++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
@@ -819,8 +819,8 @@ static void rkisp1_hst_config_v10(struct rkisp1_params *params,
 		     arg->meas_window.v_offs);
 
 	block_hsize = arg->meas_window.h_size /
-		      RKISP1_CIF_ISP_HIST_COLUMN_NUM_V10 - 1;
-	block_vsize = arg->meas_window.v_size / RKISP1_CIF_ISP_HIST_ROW_NUM_V10 - 1;
+		      RKISP1_CIF_ISP_HIST_COLUMN_NUM_V10;
+	block_vsize = arg->meas_window.v_size / RKISP1_CIF_ISP_HIST_ROW_NUM_V10;
 
 	rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_HIST_H_SIZE_V10,
 		     block_hsize);

-- 
Krzysztof "Chris" Hałasa

Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa

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