From patchwork Mon May 16 12:47:02 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Ripard X-Patchwork-Id: 9102601 Return-Path: X-Original-To: patchwork-dri-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 2F185BF440 for ; Mon, 16 May 2016 12:48:14 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5176D20279 for ; Mon, 16 May 2016 12:48:09 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id C6E0B202C8 for ; Mon, 16 May 2016 12:48:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 528346E41B; Mon, 16 May 2016 12:47:45 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail.free-electrons.com (down.free-electrons.com [37.187.137.238]) by gabe.freedesktop.org (Postfix) with ESMTP id 461536E407 for ; Mon, 16 May 2016 12:47:31 +0000 (UTC) Received: by mail.free-electrons.com (Postfix, from userid 110) id 9B85D603; Mon, 16 May 2016 14:47:30 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from localhost (LStLambert-657-1-97-87.w90-63.abo.wanadoo.fr [90.63.216.87]) by mail.free-electrons.com (Postfix) with ESMTPSA id 48902281; Mon, 16 May 2016 14:47:30 +0200 (CEST) From: Maxime Ripard To: Rob Herring , Chen-Yu Tsai , Mike Turquette , Stephen Boyd , Daniel Vetter , David Airlie Subject: [PATCH 02/20] clk: multiplier: Prevent the multiplier from under / over flowing Date: Mon, 16 May 2016 14:47:02 +0200 Message-Id: <1463402840-17062-3-git-send-email-maxime.ripard@free-electrons.com> X-Mailer: git-send-email 2.8.2 In-Reply-To: <1463402840-17062-1-git-send-email-maxime.ripard@free-electrons.com> References: <1463402840-17062-1-git-send-email-maxime.ripard@free-electrons.com> Cc: devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, Laurent Pinchart , Maxime Ripard , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP In the current multiplier base clock implementation, if the CLK_SET_RATE_PARENT flag isn't set, the code will not make sure that the multiplier computed remains within the boundaries of our clock. This means that if the clock we want to reach is below the parent rate, or if the multiplier is above the maximum that we can reach, we will end up with a completely bogus one that the clock cannot achieve. Fixes: f2e0a53271a4 ("clk: Add a basic multiplier clock") Signed-off-by: Maxime Ripard --- drivers/clk/clk-multiplier.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/clk/clk-multiplier.c b/drivers/clk/clk-multiplier.c index 9e449c7b751c..dc037c957acd 100644 --- a/drivers/clk/clk-multiplier.c +++ b/drivers/clk/clk-multiplier.c @@ -52,14 +52,28 @@ static unsigned long __bestmult(struct clk_hw *hw, unsigned long rate, unsigned long *best_parent_rate, u8 width, unsigned long flags) { + struct clk_multiplier *mult = to_clk_multiplier(hw); unsigned long orig_parent_rate = *best_parent_rate; unsigned long parent_rate, current_rate, best_rate = ~0; unsigned int i, bestmult = 0; + unsigned int maxmult = (1 << width) - 1; + + if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) { + bestmult = rate / orig_parent_rate; + + /* Make sure we don't end up with a 0 multiplier */ + if ((bestmult == 0) && + !(mult->flags & CLK_MULTIPLIER_ZERO_BYPASS)) + bestmult = 1; - if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) - return rate / *best_parent_rate; + /* Make sure we don't overflow the multiplier */ + if (bestmult > maxmult) + bestmult = maxmult; + + return bestmult; + } - for (i = 1; i < ((1 << width) - 1); i++) { + for (i = 1; i < maxmult; i++) { if (rate == orig_parent_rate * i) { /* * This is the best case for us if we have a