From patchwork Fri Sep 20 15:39:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Alexandre Belloni X-Patchwork-Id: 11154583 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ED45016B1 for ; Fri, 20 Sep 2019 15:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5A0E20B7C for ; Fri, 20 Sep 2019 15:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391565AbfITPjQ (ORCPT ); Fri, 20 Sep 2019 11:39:16 -0400 Received: from relay9-d.mail.gandi.net ([217.70.183.199]:34933 "EHLO relay9-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391054AbfITPjQ (ORCPT ); Fri, 20 Sep 2019 11:39:16 -0400 X-Originating-IP: 86.207.98.53 Received: from localhost (aclermont-ferrand-651-1-259-53.w86-207.abo.wanadoo.fr [86.207.98.53]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay9-d.mail.gandi.net (Postfix) with ESMTPSA id AE20FFF811; Fri, 20 Sep 2019 15:39:12 +0000 (UTC) From: Alexandre Belloni To: Stephen Boyd Cc: Nicolas Ferre , Claudiu Beznea , Michael Turquette , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Alexandre Belloni , =?utf-8?q?Uwe_Kleine-K?= =?utf-8?q?=C3=B6nig?= Subject: [PATCH] clk: at91: avoid sleeping early Date: Fri, 20 Sep 2019 17:39:06 +0200 Message-Id: <20190920153906.20887-1-alexandre.belloni@bootlin.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org It is not allowed to sleep to early in the boot process and this may lead to kernel issues if the bootloader didn't prepare the slow clock and main clock. This results in the following error and dump stack on the AriettaG25: bad: scheduling from the idle thread! Ensure it is possible to sleep, else simply have a delay. Reported-by: Uwe Kleine-König Signed-off-by: Alexandre Belloni Tested-by: Uwe Kleine-König --- Note that this was already discussed a while ago and Arnd said this approach was reasonable: https://lore.kernel.org/lkml/6120818.MyeJZ74hYa@wuerfel/ drivers/clk/at91/clk-main.c | 5 ++++- drivers/clk/at91/sckc.c | 20 ++++++++++++++++---- 2 files changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c index f607ee702c83..ccd48e7a3d74 100644 --- a/drivers/clk/at91/clk-main.c +++ b/drivers/clk/at91/clk-main.c @@ -293,7 +293,10 @@ static int clk_main_probe_frequency(struct regmap *regmap) regmap_read(regmap, AT91_CKGR_MCFR, &mcfr); if (mcfr & AT91_PMC_MAINRDY) return 0; - usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT); + if (system_state < SYSTEM_RUNNING) + udelay(MAINF_LOOP_MIN_WAIT); + else + usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT); } while (time_before(prep_time, timeout)); return -ETIMEDOUT; diff --git a/drivers/clk/at91/sckc.c b/drivers/clk/at91/sckc.c index 9bfe9a28294a..fac0ca56d42d 100644 --- a/drivers/clk/at91/sckc.c +++ b/drivers/clk/at91/sckc.c @@ -76,7 +76,10 @@ static int clk_slow_osc_prepare(struct clk_hw *hw) writel(tmp | osc->bits->cr_osc32en, sckcr); - usleep_range(osc->startup_usec, osc->startup_usec + 1); + if (system_state < SYSTEM_RUNNING) + udelay(osc->startup_usec); + else + usleep_range(osc->startup_usec, osc->startup_usec + 1); return 0; } @@ -187,7 +190,10 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw) writel(readl(sckcr) | osc->bits->cr_rcen, sckcr); - usleep_range(osc->startup_usec, osc->startup_usec + 1); + if (system_state < SYSTEM_RUNNING) + udelay(osc->startup_usec); + else + usleep_range(osc->startup_usec, osc->startup_usec + 1); return 0; } @@ -288,7 +294,10 @@ static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index) writel(tmp, sckcr); - usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1); + if (system_state < SYSTEM_RUNNING) + udelay(SLOWCK_SW_TIME_USEC); + else + usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1); return 0; } @@ -533,7 +542,10 @@ static int clk_sama5d4_slow_osc_prepare(struct clk_hw *hw) return 0; } - usleep_range(osc->startup_usec, osc->startup_usec + 1); + if (system_state < SYSTEM_RUNNING) + udelay(osc->startup_usec); + else + usleep_range(osc->startup_usec, osc->startup_usec + 1); osc->prepared = true; return 0;