From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754789AbaEFU1U (ORCPT ); Tue, 6 May 2014 16:27:20 -0400 Received: from mail-yh0-f51.google.com ([209.85.213.51]:46314 "EHLO mail-yh0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517AbaEFU1T (ORCPT ); Tue, 6 May 2014 16:27:19 -0400 From: Fabio Estevam To: mturquette@linaro.org Cc: linux-kernel@vger.kernel.org, shawn.guo@freescale.com, kernel@pengutronix.de, maxime.coquelin@st.com, linux-arm-kernel@lists.infradead.org, Fabio Estevam Subject: [PATCH] clk: clk-divider: Fix infinite loop for table divider Date: Tue, 6 May 2014 17:26:45 -0300 Message-Id: <1399408005-4209-1-git-send-email-festevam@gmail.com> X-Mailer: git-send-email 1.8.3.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fabio Estevam Since commit e7489693b3 (clk: divider: Optimize clk_divider_bestdiv loop) we notice a system hang on mx6qboard. The cause for the hang is well explained by Sascha Hauer [1]: "This cannot work. _round_up_table is implemented like this: static int _round_up_table(const struct clk_div_table *table, int div) { const struct clk_div_table *clkt; int up = _get_table_maxdiv(table); for (clkt = table; clkt->div; clkt++) { if (clkt->div == div) return clkt->div; ... } ... } Here when a table entry matches the input div this function will return exactly the input div. This means _next_div() will always return the same value and clk_divider_bestdiv() has an infinite loop: for (i = 1; i <= maxdiv; i = _next_div(divider, i)) { ... } " [1] http://marc.info/?l=linux-arm-kernel&m=139940658726253&w=2 Remove the 'return _round_up_table' so that the system can work normally again. Signed-off-by: Fabio Estevam --- drivers/clk/clk-divider.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c index b3c8396..fc3e344 100644 --- a/drivers/clk/clk-divider.c +++ b/drivers/clk/clk-divider.c @@ -246,8 +246,6 @@ static int _next_div(struct clk_divider *divider, int div) if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) return __roundup_pow_of_two(div); - if (divider->table) - return _round_up_table(divider->table, div); return div; } -- 1.8.3.2