From nobody Sat Jun 20 01:01:36 2026 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 BC215C433F5 for ; Sat, 26 Mar 2022 12:24:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232868AbiCZM0D (ORCPT ); Sat, 26 Mar 2022 08:26:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232803AbiCZM0B (ORCPT ); Sat, 26 Mar 2022 08:26:01 -0400 X-Greylist: delayed 455 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sat, 26 Mar 2022 05:24:15 PDT Received: from mail-m17637.qiye.163.com (mail-m17637.qiye.163.com [59.111.176.37]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99B4211987A; Sat, 26 Mar 2022 05:24:15 -0700 (PDT) Received: from localhost.localdomain (unknown [58.22.7.114]) by mail-m17637.qiye.163.com (Hmail) with ESMTPA id BD5AE98029A; Sat, 26 Mar 2022 20:16:37 +0800 (CST) From: Sugar Zhang To: vkoul@kernel.org Cc: Sugar Zhang , Huibin Hong , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] dmaengine: pl330: Fix unbalanced runtime PM Date: Sat, 26 Mar 2022 20:16:28 +0800 Message-Id: <1648296988-45745-1-git-send-email-sugar.zhang@rock-chips.com> X-Mailer: git-send-email 2.7.4 X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgPGg8OCBgUHx5ZQUlOS1dZCBgUCR5ZQVlLVUtZV1 kWDxoPAgseWUFZKDYvK1lXWShZQUlKS0tKN1dZLVlBSVdZDwkaFQgSH1lBWUMZTh1WSkxOSBhLTE ofTh5CVRMBExYaEhckFA4PWVdZFhoPEhUdFFlBWU9LSFVKSktISkNVS1kG X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6OU06Ejo5FD4DLxY1IT40HBYe NjkaCR9VSlVKTU9DSUJNQkJDSkhDVTMWGhIXVQgOHBoJVQETGhUcOwkUGBBWGBMSCwhVGBQWRVlX WRILWUFZTkNVSUlVTFVKSk9ZV1kIAVlBSE9CTTcG X-HM-Tid: 0a7fc628340ed992kuwsbd5ae98029a Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This driver use runtime PM autosuspend mechanism to manager clk. pm_runtime_use_autosuspend(&adev->dev); pm_runtime_set_autosuspend_delay(&adev->dev, PL330_AUTOSUSPEND_DELAY); So, after ref count reached to zero, it will enter suspend after the delay time elapsed. The unbalanced PM: * May cause dmac the next start failed. * May cause dmac read unexpected state. * May cause dmac stall if power down happen at the middle of the transfer. e.g. may lose ack from AXI bus and stall. Considering the following situation: DMA TERMINATE TASKLET ROUTINE | | | issue_pending | | | pch->active =3D true | pm_runtime_get pm_runtime_put(if active) | pch->active =3D false | | work_list empty | | | pm_runtime_put(force) | | At this point, it's unbalanced(1 get / 2 put). After this patch: DMA TERMINATE TASKLET ROUTINE | | | issue_pending | | | pch->active =3D true | pm_runtime_get pm_runtime_put(if active) | pch->active =3D false | | work_list empty | | | pm_runtime_put(if active) | | Now, it's balanced(1 get / 1 put). Fixes: commit 5c9e6c2b2ba3 ("dmaengine: pl330: Fix runtime PM support for terminat= ed transfers") commit ae43b3289186 ("ARM: 8202/1: dmaengine: pl330: Add runtime Power Mana= gement support v12") Signed-off-by: Huibin Hong Signed-off-by: Sugar Zhang --- drivers/dma/pl330.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 858400e..ccd430e 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -2084,7 +2084,7 @@ static void pl330_tasklet(struct tasklet_struct *t) spin_lock(&pch->thread->dmac->lock); _stop(pch->thread); spin_unlock(&pch->thread->dmac->lock); - power_down =3D true; + power_down =3D pch->active; pch->active =3D false; } else { /* Make sure the PL330 Channel thread is active */ --=20 2.7.4