From nobody Wed Dec 17 10:59:01 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 D291AEE49AC for ; Tue, 22 Aug 2023 16:20:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237693AbjHVQUT (ORCPT ); Tue, 22 Aug 2023 12:20:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237667AbjHVQUK (ORCPT ); Tue, 22 Aug 2023 12:20:10 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92DE9CDF for ; Tue, 22 Aug 2023 09:20:07 -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 3162687E1; Tue, 22 Aug 2023 18:18:48 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1692721129; bh=PZWyhC5dbXtcQIPCQnixR51q/63Hv20ub79Oc4c8dPc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=tD8AtyDbESZPURfG7WTY47Qldu86Yh9/JRnPZTeCf0PKuZ4GCggMXC+/B7YlDxW3b /MS3a6YER5acYSXvon9auNZV6aYOX/us3izob9b2NGqHifBVCNaPvqW/lCiCclIvJ3 iwB5G76RWD5ezM3B+BVLtAMqyXp1/tKK7/UfGOUA= From: Tomi Valkeinen Date: Tue, 22 Aug 2023 19:19:38 +0300 Subject: [PATCH v3 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: <20230822-tc358768-v3-5-c82405dac0c1@ideasonboard.com> References: <20230822-tc358768-v3-0-c82405dac0c1@ideasonboard.com> In-Reply-To: <20230822-tc358768-v3-0-c82405dac0c1@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 X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2543; i=tomi.valkeinen@ideasonboard.com; h=from:subject:message-id; bh=PZWyhC5dbXtcQIPCQnixR51q/63Hv20ub79Oc4c8dPc=; b=owEBbQKS/ZANAwAIAfo9qoy8lh71AcsmYgBk5OAsXsMFM7hC1l9gz3dS7LioxUL6d6mGfbglO D15zCBtIWKJAjMEAAEIAB0WIQTEOAw+ll79gQef86f6PaqMvJYe9QUCZOTgLAAKCRD6PaqMvJYe 9Q/qD/wNTI5SV6F0s47NHHdMSlmVAYcBZE4u8Sv+xyasR172qllVfKjZASiT7qccB3EAtkUnYBG W1DlhQCgNXVYgU+i0X2QSMwElJxeOiSGjP6hrZ12Tc1Prhjq61fp+EDdxV/azo6A05F42thRGTs lRtttA5YUGOENZAFku7aPq896Yal6654a8sjRK0kMW/kwk5qSs+Thn4Xo36lS9OjuBeKR+3tXWA Is39dd6U3Wwc+jEappVufAPkpg9SMPg2S3v56AR04upIsM73whD7ID1DlaxOpyEAnRW+Wt++yOw wjDuiw/feUm744HfQ+KQgTtpwQ69/zD0VWFVUv2fsoDHRIjCiFeF879K7oXbywqPoYLQIY6QE3B aZR986ewMnGw1aRicCCXbSpOVP1lAznR1zYDKQQ/jaNMn95+y5G84IrBH9yUba2t65jzwd5uPqh w7ZzPevn8gX18z+qGLADxjIwOxI23QmykS2tqSUIZbe/8+BAKLjvBCuyIQteI2UGAcOKTu9B2/b Fus8YSRQaEw0w+vFm9kTN8uJdmv7eFbPWEthh0rrRLYOd0IhA3v03iiWaKLCad9mviq7u0n3469 EL52GZiNPvZ0iLnXtSKjjHrP4W2xym1rPsziytuqBGkeu6Ydpz527pe6l0u/mkskgfYKZ5iCYi0 K02hlPMrPkLSUWw== 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 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