From nobody Thu Sep 11 16:51:08 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 553E6EB8FAD for ; Wed, 6 Sep 2023 06:51:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242011AbjIFGvt (ORCPT ); Wed, 6 Sep 2023 02:51:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232476AbjIFGvi (ORCPT ); Wed, 6 Sep 2023 02:51:38 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 657A2CFD for ; Tue, 5 Sep 2023 23:51:34 -0700 (PDT) Received: from [127.0.1.1] (91-154-35-171.elisa-laajakaista.fi [91.154.35.171]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id E027B1536; Wed, 6 Sep 2023 08:50:03 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1693983004; bh=gVqp/W0PhAL3EfV0HWVnGx4la8fAeaMt695Id26ctC0=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZqWL8vcWUJ54WZyBnEOpvlsnUT9NYMiKpxMKcn2fRw+cRe452ESJg0oDFj6Q8T8lQ 1UZ8maNKagsPaPkCtBi9IWzkhX6fpBHcNPRRGb0SlpSdtHMkLxLnTBzMe1hHJ4pixO SrtmD5DCL4rFScikjWUbDlXQ89oAaJtTdAJJRnqI= From: Tomi Valkeinen Date: Wed, 06 Sep 2023 09:50:52 +0300 Subject: [PATCH v4 05/12] drm/bridge: tc358768: Cleanup PLL calculations MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20230906-tc358768-v4-5-31725f008a50@ideasonboard.com> References: <20230906-tc358768-v4-0-31725f008a50@ideasonboard.com> In-Reply-To: <20230906-tc358768-v4-0-31725f008a50@ideasonboard.com> To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , David Airlie , Daniel Vetter , =?utf-8?q?P=C3=A9ter_Ujfalusi?= , Maxim Schwalm , Francesco Dolcini Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Aradhya Bhatia , Tomi Valkeinen , Marcel Ziswiler X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2667; i=tomi.valkeinen@ideasonboard.com; h=from:subject:message-id; bh=gVqp/W0PhAL3EfV0HWVnGx4la8fAeaMt695Id26ctC0=; b=owEBbQKS/ZANAwAIAfo9qoy8lh71AcsmYgBk+CFpw0pd36D5QvJBKTIrRBV5DNBSNUhtjPX4A 5Ra+O/VzDWJAjMEAAEIAB0WIQTEOAw+ll79gQef86f6PaqMvJYe9QUCZPghaQAKCRD6PaqMvJYe 9cpuD/4jv7eE215j4bbCAgkKOSK3MWMPvLJLxRjm8grHLGJ802Am7k9IuOAzjlT5i9w/AKcnLBT TuKpbOxEq3yGUlsnSQcBrU7VHZ58/ms6+pprEtCulfsJJwjyXQw1iF7+73zM2ZUGiKKxJ6TgxYX lBykvraNR0RPlx6niNhxpwF+TS/w7rStyPDmxFj4wDKqW5CCqUq3KrmvRmlDyCHGoE49xToZI6Q 1kBi4bHY9IsZhlXdlfvPDRQ+aWA3CNqlrqfa26O2lcmbmzPNQp8cJJiDKRvfkhtcVZ6ZyP9gw7x 5Axu5xI9Xt4jMLQ4fMZKIfNATLa/2OVl8gePkMjCi4cD//Mit+Ecwadb8llgyX0L7yfDmXOze+i mgbGrPuxhFmMLgE9DgiTDVwfQVc6+ttk07FWg1AhQ8SI/9U0J+MSRMbUtCW3OcYg10RmfH62Pwf HSbf/c4vBpB9Td5BvcAnVmfQlFfpseM93uq68pzhg0Pe+3MlsNN1fowoxfHs1NWAvIbSfbBF1iN /9G8HuDPrEv3kw2rwyOGHVHwmnKSjgwIQazA5zDozfpbW9r9+C4cVkZ9+gJJA1VVtU9p/XHzI8c nZa/CaK8mxeCJJgU5wym3mRmkPrrB3meyQJFdcKlzvjH2OwJGGTM9KATuIogQS7Pu2Q/eHS/P+b dy5rZI1WltfStSg== X-Developer-Key: i=tomi.valkeinen@ideasonboard.com; a=openpgp; fpr=C4380C3E965EFD81079FF3A7FA3DAA8CBC961EF5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As is quite common, some of TC358768's PLL register fields are to be programmed with (value - 1). Specifically, the FBD and PRD, multiplier and divider, are such fields. However, what the driver currently does is that it considers that the formula used for PLL rate calculation is: RefClk * [(FBD + 1)/ (PRD + 1)] * [1 / (2^FRS)] where FBD and PRD are values directly from the registers, while a more sensible way to look at it is: RefClk * FBD / PRD * (1 / (2^FRS)) and when the FBD and PRD values are written to the registers, they will be subtracted by one. Change the driver accordingly, as it simplifies the PLL code. Reviewed-by: Peter Ujfalusi Tested-by: Maxim Schwalm # Asus TF700T Tested-by: Marcel Ziswiler Signed-off-by: Tomi Valkeinen --- drivers/gpu/drm/bridge/tc358768.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc3= 58768.c index 99992af23f1e..a465674f1e2e 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -316,7 +316,7 @@ static int tc358768_calc_pll(struct tc358768_priv *priv, =20 target_pll =3D tc358768_pclk_to_pll(priv, mode->clock * 1000); =20 - /* pll_clk =3D RefClk * [(FBD + 1)/ (PRD + 1)] * [1 / (2^FRS)] */ + /* pll_clk =3D RefClk * FBD / PRD * (1 / (2^FRS)) */ =20 for (i =3D 0; i < ARRAY_SIZE(frs_limits); i++) if (target_pll >=3D frs_limits[i]) @@ -336,19 +336,19 @@ static int tc358768_calc_pll(struct tc358768_priv *pr= iv, best_prd =3D 0; best_fbd =3D 0; =20 - for (prd =3D 0; prd < 16; ++prd) { - u32 divisor =3D (prd + 1) * (1 << frs); + for (prd =3D 1; prd <=3D 16; ++prd) { + u32 divisor =3D prd * (1 << frs); u32 fbd; =20 - for (fbd =3D 0; fbd < 512; ++fbd) { + for (fbd =3D 1; fbd <=3D 512; ++fbd) { u32 pll, diff, pll_in; =20 - pll =3D (u32)div_u64((u64)refclk * (fbd + 1), divisor); + pll =3D (u32)div_u64((u64)refclk * fbd, divisor); =20 if (pll >=3D max_pll || pll < min_pll) continue; =20 - pll_in =3D (u32)div_u64((u64)refclk, prd + 1); + pll_in =3D (u32)div_u64((u64)refclk, prd); if (pll_in < 4000000) continue; =20 @@ -611,7 +611,7 @@ static int tc358768_setup_pll(struct tc358768_priv *pri= v, mode->clock * 1000); =20 /* PRD[15:12] FBD[8:0] */ - tc358768_write(priv, TC358768_PLLCTL0, (prd << 12) | fbd); + tc358768_write(priv, TC358768_PLLCTL0, ((prd - 1) << 12) | (fbd - 1)); =20 /* FRS[11:10] LBWS[9:8] CKEN[4] RESETB[1] EN[0] */ tc358768_write(priv, TC358768_PLLCTL1, --=20 2.34.1