From patchwork Thu Jan 21 02:56:22 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Agner X-Patchwork-Id: 571016 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 7F78E140144 for ; Thu, 21 Jan 2016 13:56:37 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; secure) header.d=agner.ch header.i=@agner.ch header.b=a+aiP8Au; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758047AbcAUC4g (ORCPT ); Wed, 20 Jan 2016 21:56:36 -0500 Received: from mail.kmu-office.ch ([178.209.48.109]:35036 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965297AbcAUC4e (ORCPT ); Wed, 20 Jan 2016 21:56:34 -0500 Received: from trochilidae.toradex.int (75-146-58-181-Washington.hfc.comcastbusiness.net [75.146.58.181]) by mail.kmu-office.ch (Postfix) with ESMTPSA id 630D45C0250; Thu, 21 Jan 2016 03:55:24 +0100 (CET) From: Stefan Agner To: thierry.reding@gmail.com Cc: Xiubo.Lee@gmail.com, linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Stefan Agner , Mark Brown Subject: [PATCH] pwm: ftm: use flat regmap cache Date: Wed, 20 Jan 2016 18:56:22 -0800 Message-Id: <1453344982-4529-1-git-send-email-stefan@agner.ch> X-Mailer: git-send-email 2.7.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1453344925; bh=T7C1hwyMe2RSuRC2pzKGmwEJHkBQlhRVgW6AAFkibb4=; h=From:To:Cc:Subject:Date:Message-Id; b=a+aiP8Aufa9vp3+G53m3Fldi8O2dqx6VL4Bz9vobIyiGzBdtODH/r/OsWlMdYrQp5LlLUcet1LMHe+G2DKgU6fMqgOdgc5m5+kKLFmNN2X52demPmUIxL8lLrVZVcXS67jRnKQpK6MzEpvxSrLB5PO57mEfdqO6YzcC1KRSITwM= Sender: linux-pwm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Use flat regmap cache to avoid lockdep warning at probe: [ 0.697285] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x15c/0x160() [ 0.697449] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) The RB-tree regmap cache needs to allocate new space on first writes. However, allocations in an atomic context (e.g. when a spinlock is held) are not allowed. The function regmap_write calls map->lock, which acquires a spinlock in the fast_io case. Since the pwm-fsl-ftm driver uses MMIO, the regmap bus of type regmap_mmio is being used which has fast_io set to true. The MMIO space of the pwm-fsl-ftm driver is reasonable condense, hence using the much faster flat regmap cache is anyway the better choice. Signed-off-by: Stefan Agner Cc: Mark Brown --- drivers/pwm/pwm-fsl-ftm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c index f9dfc8b..ed39e8e 100644 --- a/drivers/pwm/pwm-fsl-ftm.c +++ b/drivers/pwm/pwm-fsl-ftm.c @@ -414,7 +414,7 @@ static const struct regmap_config fsl_pwm_regmap_config = { .max_register = FTM_PWMLOAD, .volatile_reg = fsl_pwm_volatile_reg, - .cache_type = REGCACHE_RBTREE, + .cache_type = REGCACHE_FLAT, }; static int fsl_pwm_probe(struct platform_device *pdev)