From nobody Sun Feb 8 21:32:37 2026 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 432272E65D; Mon, 5 Jan 2026 17:53:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767635588; cv=none; b=nEpUqCRxXgzfwpt0XUyCHBMI4FLh2TE2bnfeld8AwFZEd3vnbDptDaqNlMJ20rWAxO/An4xWSf+JorckLiFmHeC/eJQajFnTwoQfMnj3h9GrF5pMvinWvlpc3bPJymIsp0SSdUX5DJkkr4uMeFX5r4h8bPaU7m/0LEBsFLODv74= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767635588; c=relaxed/simple; bh=lCiCf/XC7B3kc67ZN41wbPvKknJELjJSALJ9hoomOVg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=VgctxtT8du2Zr88N4Pnt5iBWEVkOja6Pq93O/Qd07K380PL6K4Pg+xUy5161WkKZc3LCdiaH6TTBlqxBixMPf8Uz/V0miVv42LqRMIk/OkVjJY1wHdtYB2ly90VSuh+2Z9xWBnaB5OFfyF0FWLcADa/2kJ/vvf1M7BwSuaaK9Ew= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=iZFy1usK; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=Xc3f6UBe; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="iZFy1usK"; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="Xc3f6UBe" Received: from smtp2.mailbox.org (smtp2.mailbox.org [10.196.197.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4dlMMz1dkfz9tQq; Mon, 5 Jan 2026 18:53:03 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1767635583; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=mlFYT/HEOvUY7CDKakI9f1tmEuOow/Z3hA5FQFme7mI=; b=iZFy1usK2fdQj0XU3g3+JdxY/JSJ+ylW8JeV5uq8c9f0qo3R3muAx39MlLs4UWDbgkTuah 7MTSOaplzhptD0plupo4tdzWB0Vt1kmh95U6naHbV49afTsZ8hvkAEzajzlXfEHQC18Uk1 WdTQWhaIBUc/DfEiv8Ji5Ut0BA2+WePHAvjEJtOarV1pqVSAhRbE85j7h6SlcgvWF1y99b Um3Yhas5G9kTyxs81TeZRVpdtbf3PVkTDGQpfbrzkJfCym2dXsV/mupY3R8NVzsZyfcKNW uV3K1hzMZKUDAuIM8gd2F+NUwBcyXJRpOGqArKnEY/T+ycg2YQTYjRYnddSmBA== From: Marek Vasut DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1767635580; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=mlFYT/HEOvUY7CDKakI9f1tmEuOow/Z3hA5FQFme7mI=; b=Xc3f6UBe9tmQN9xVsvtBBJ+depcCxoJX3bhMBBQMV5iWEqhkSXlZF3pDGaXvL+ytc6n+e7 y1rjHv9MBnrzhwnoPgDXVTWd3QD6y+EAgqHrmaVxqyLwOD3OfWJ5PL99cgsranRHFqfVdC J63Dx9mGRAkh1WyEpnUPLdIlVKZh9FVJFdL5N3/Zfgev0i7fxC506ucZaN/CUmKzgjM1WF V9hvC0TOIYM4SeXpOTlH8D2XbSUGQQa9oPJgpPbNe0xHo14xvYYmyXaMtFuuDkafIM5Yk2 ZzA0xI2iJyufGskZmUTNOqF9AAOlMIlk22F8aCoGxYIwgUqhJXyYzNVRU9AN5w== To: dri-devel@lists.freedesktop.org Cc: Marek Vasut , kernel test robot , David Airlie , Geert Uytterhoeven , Kieran Bingham , Laurent Pinchart , Maarten Lankhorst , Magnus Damm , Maxime Ripard , Simona Vetter , Thomas Zimmermann , Tomi Valkeinen , linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: [PATCH v2] drm/rcar-du: dsi: Clean up VCLK divider calculation Date: Mon, 5 Jan 2026 18:52:04 +0100 Message-ID: <20260105175250.64309-1-marek.vasut+renesas@mailbox.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-MBO-RS-META: 6czwgu3o71sasbatj75ppfox5y8wi7nc X-MBO-RS-ID: 22b2408a7d8588c0a71 Content-Type: text/plain; charset="utf-8" Currently, in rcar_mipi_dsi_parameters_calc(), the VCLK divider is stored in setup_info structure as BIT(divider). The rcar_mipi_dsi_parameters_calc() is called at the early beginning of rcar_mipi_dsi_startup() function. Later, in the same rcar_mipi_dsi_startup() function, the stored BIT(divider) value is passed to __ffs() to calculate back the divider out of the value again. Factor out VCLK divider calculation into rcar_mipi_dsi_vclk_divider() function and call the function from both rcar_mipi_dsi_parameters_calc() and rcar_mipi_dsi_startup() to avoid this back and forth BIT() and _ffs() and avoid unnecessarily storing the divider value in setup_info at all. This rework has a slight side-effect, in that it should allow the compiler to better evaluate the code and avoid compiler warnings about variable value overflows, which can never happen. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202512051834.bESvhDiG-lkp@int= el.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202512222321.TeY4VbvK-lkp@int= el.com/ Signed-off-by: Marek Vasut Reviewed-by: Laurent Pinchart --- Cc: David Airlie Cc: Geert Uytterhoeven Cc: Kieran Bingham Cc: Laurent Pinchart Cc: Maarten Lankhorst Cc: Magnus Damm Cc: Maxime Ripard Cc: Simona Vetter Cc: Thomas Zimmermann Cc: Tomi Valkeinen Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org --- V2: Use BIT_U16() --- .../gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c | 35 ++++++++++++++----- 1 file changed, 26 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/= drm/renesas/rcar-du/rcar_mipi_dsi.c index 4ef2e3c129ed7..508977b9e8926 100644 --- a/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c @@ -84,7 +84,6 @@ struct dsi_setup_info { unsigned long fout; u16 m; u16 n; - u16 vclk_divider; const struct dsi_clk_config *clkset; }; =20 @@ -335,10 +334,24 @@ rcar_mipi_dsi_post_init_phtw_v4h(struct rcar_mipi_dsi= *dsi, * Hardware Setup */ =20 +static unsigned int rcar_mipi_dsi_vclk_divider(struct rcar_mipi_dsi *dsi, + struct dsi_setup_info *setup_info) +{ + switch (dsi->info->model) { + case RCAR_DSI_V3U: + default: + return (setup_info->clkset->vco_cntrl >> 4) & 0x3; + + case RCAR_DSI_V4H: + return (setup_info->clkset->vco_cntrl >> 3) & 0x7; + } +} + static void rcar_mipi_dsi_pll_calc(struct rcar_mipi_dsi *dsi, unsigned long fin_rate, unsigned long fout_target, - struct dsi_setup_info *setup_info) + struct dsi_setup_info *setup_info, + u16 vclk_divider) { unsigned int best_err =3D -1; const struct rcar_mipi_dsi_device_info *info =3D dsi->info; @@ -360,7 +373,7 @@ static void rcar_mipi_dsi_pll_calc(struct rcar_mipi_dsi= *dsi, if (fout < info->fout_min || fout > info->fout_max) continue; =20 - fout =3D div64_u64(fout, setup_info->vclk_divider); + fout =3D div64_u64(fout, vclk_divider); =20 if (fout < setup_info->clkset->min_freq || fout > setup_info->clkset->max_freq) @@ -390,7 +403,9 @@ static void rcar_mipi_dsi_parameters_calc(struct rcar_m= ipi_dsi *dsi, unsigned long fout_target; unsigned long fin_rate; unsigned int i; + unsigned int div; unsigned int err; + u16 vclk_divider; =20 /* * Calculate Fout =3D dot clock * ColorDepth / (2 * Lane Count) @@ -412,18 +427,20 @@ static void rcar_mipi_dsi_parameters_calc(struct rcar= _mipi_dsi *dsi, =20 fin_rate =3D clk_get_rate(clk); =20 + div =3D rcar_mipi_dsi_vclk_divider(dsi, setup_info); + switch (dsi->info->model) { case RCAR_DSI_V3U: default: - setup_info->vclk_divider =3D 1 << ((clk_cfg->vco_cntrl >> 4) & 0x3); + vclk_divider =3D BIT_U16(div); break; =20 case RCAR_DSI_V4H: - setup_info->vclk_divider =3D 1 << (((clk_cfg->vco_cntrl >> 3) & 0x7) + 1= ); + vclk_divider =3D BIT_U16(div + 1); break; } =20 - rcar_mipi_dsi_pll_calc(dsi, fin_rate, fout_target, setup_info); + rcar_mipi_dsi_pll_calc(dsi, fin_rate, fout_target, setup_info, vclk_divid= er); =20 /* Find hsfreqrange */ setup_info->hsfreq =3D setup_info->fout * 2; @@ -439,7 +456,7 @@ static void rcar_mipi_dsi_parameters_calc(struct rcar_m= ipi_dsi *dsi, dev_dbg(dsi->dev, "Fout =3D %u * %lu / (%u * %u * %u) =3D %lu (target %lu Hz, error %d.%02= u%%)\n", setup_info->m, fin_rate, dsi->info->n_mul, setup_info->n, - setup_info->vclk_divider, setup_info->fout, fout_target, + vclk_divider, setup_info->fout, fout_target, err / 100, err % 100); =20 dev_dbg(dsi->dev, @@ -653,11 +670,11 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi= *dsi, switch (dsi->info->model) { case RCAR_DSI_V3U: default: - vclkset |=3D VCLKSET_DIV_V3U(__ffs(setup_info.vclk_divider)); + vclkset |=3D VCLKSET_DIV_V3U(rcar_mipi_dsi_vclk_divider(dsi, &setup_info= )); break; =20 case RCAR_DSI_V4H: - vclkset |=3D VCLKSET_DIV_V4H(__ffs(setup_info.vclk_divider) - 1); + vclkset |=3D VCLKSET_DIV_V4H(rcar_mipi_dsi_vclk_divider(dsi, &setup_info= )); break; } =20 --=20 2.51.0