linux-kernel - [PATCH 09/17] drm: renesas: rz-du: mipi

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Message-ID: <20250330210717.46080-10-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Sun, 30 Mar 2025 22:07:05 +0100
From: Prabhakar <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>,
	Andrzej Hajda <andrzej.hajda@...el.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Robert Foss <rfoss@...nel.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	Jonas Karlman <jonas@...boo.se>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Biju Das <biju.das.jz@...renesas.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-media@...r.kernel.org,
	linux-clk@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH 09/17] drm: renesas: rz-du: mipi_dsi: Simplify HSFREQ calculation

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Simplify the high-speed clock frequency (HSFREQ) calculation by removing
the redundant multiplication and division by 8. The updated equation:

    hsfreq = (mode->clock * bpp) / (dsi->lanes);

produces the same result while improving readability and clarity.

Additionally, update the comment to clarify the relationship between HS
clock bit frequency, HS byte clock frequency, and HSFREQ.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
index c6f60b7f203b..746f82442c01 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -277,10 +277,10 @@ static int rzg2l_mipi_dsi_startup(struct rzg2l_mipi_dsi *dsi,
 	 *       hsclk: DSI HS Byte clock frequency (Hz)
 	 *       lanes: number of data lanes
 	 *
-	 * hsclk(bit) = hsclk(byte) * 8
+	 * hsclk(bit) = hsclk(byte) * 8 = hsfreq
 	 */
 	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
-	hsfreq = (mode->clock * bpp * 8) / (8 * dsi->lanes);
+	hsfreq = (mode->clock * bpp) / dsi->lanes;
 
 	ret = pm_runtime_resume_and_get(dsi->dev);
 	if (ret < 0)
-- 
2.49.0