From patchwork Fri May 26 17:10:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Reichel X-Patchwork-Id: 13257192 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 9B632C7EE2C for ; Fri, 26 May 2023 17:11:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242242AbjEZRLD (ORCPT ); Fri, 26 May 2023 13:11:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236835AbjEZRLC (ORCPT ); Fri, 26 May 2023 13:11:02 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01099FB; Fri, 26 May 2023 10:11:00 -0700 (PDT) Received: from jupiter.universe (dyndsl-091-248-132-021.ewe-ip-backbone.de [91.248.132.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: sre) by madras.collabora.co.uk (Postfix) with ESMTPSA id 872486606E94; Fri, 26 May 2023 18:10:59 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1685121059; bh=8tIgZvve58LmRVC3TweXsKlF+FYtaM8+jla/W7NnB5Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KFL5ezHXSfaf06+obC/aX5tMUYWQlwtH/YLQIw0bI7u1qHRESWBGpuCT6PnvGUR2W TzSn7HldAPBE+GWokVj+FzEXa/d9q8aQvdwl68g1H93vDFNFrmOFoThHwYT/t/hOaV 5WMAhlO0T8ran4LWdPR6yDiSxhNApaX2H7FZr2cQctlt8Ft7oWEgm0sJS4VbIzNefm bXnDGlOOlISZv/GosaJzI2mdfFZT/5ihwBBmmVET6jVEdIGTsCh+4DSGLvQ+UQkykW YKOS5w6zTTcPa4z82lbJq+buSdOgtljkJ/tm6jLeyMgGDmAYWHT89bhBKqb+fiZ4H+ xxIMgMO16mjfQ== Received: by jupiter.universe (Postfix, from userid 1000) id D26934807E2; Fri, 26 May 2023 19:10:57 +0200 (CEST) From: Sebastian Reichel To: Michael Turquette , Stephen Boyd , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Christopher Obbard , David Laight , Sebastian Reichel , kernel@collabora.com, stable@vger.kernel.org Subject: [PATCH v2 1/2] clk: composite: Fix handling of high clock rates Date: Fri, 26 May 2023 19:10:56 +0200 Message-Id: <20230526171057.66876-2-sebastian.reichel@collabora.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230526171057.66876-1-sebastian.reichel@collabora.com> References: <20230526171057.66876-1-sebastian.reichel@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org ULONG_MAX is used by a few drivers to figure out the highest available clock rate via clk_round_rate(clk, ULONG_MAX). Since abs() takes a signed value as input, the current logic effectively calculates with ULONG_MAX = -1, which results in the worst parent clock being chosen instead of the best one. For example on Rockchip RK3588 the eMMC driver tries to figure out the highest available clock rate. There are three parent clocks available resulting in the following rate diffs with the existing logic: GPLL: abs(18446744073709551615 - 1188000000) = 1188000001 CPLL: abs(18446744073709551615 - 1500000000) = 1500000001 XIN24M: abs(18446744073709551615 - 24000000) = 24000001 As a result the clock framework will promote a maximum supported clock rate of 24 MHz, even though 1.5GHz are possible. With the updated logic any casting between signed and unsigned is avoided and the numbers look like this instead: GPLL: 18446744073709551615 - 1188000000 = 18446744072521551615 CPLL: 18446744073709551615 - 1500000000 = 18446744072209551615 XIN24M: 18446744073709551615 - 24000000 = 18446744073685551615 As a result the parent with the highest acceptable rate is chosen instead of the parent clock with the lowest one. Cc: stable@vger.kernel.org Fixes: 49502408007b ("mmc: sdhci-of-dwcmshc: properly determine max clock on Rockchip") Tested-by: Christopher Obbard Signed-off-by: Sebastian Reichel Reviewed-by: AngeloGioacchino Del Regno --- drivers/clk/clk-composite.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk-composite.c b/drivers/clk/clk-composite.c index edfa94641bbf..66759fe28fad 100644 --- a/drivers/clk/clk-composite.c +++ b/drivers/clk/clk-composite.c @@ -119,7 +119,10 @@ static int clk_composite_determine_rate(struct clk_hw *hw, if (ret) continue; - rate_diff = abs(req->rate - tmp_req.rate); + if (req->rate >= tmp_req.rate) + rate_diff = req->rate - tmp_req.rate; + else + rate_diff = tmp_req.rate - req->rate; if (!rate_diff || !req->best_parent_hw || best_rate_diff > rate_diff) {