From mboxrd@z Thu Jan 1 00:00:00 1970 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 8F106C433EF for ; Sun, 17 Apr 2022 13:53:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234210AbiDQN4G (ORCPT ); Sun, 17 Apr 2022 09:56:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229496AbiDQN4E (ORCPT ); Sun, 17 Apr 2022 09:56:04 -0400 Received: from mail-m17657.qiye.163.com (mail-m17657.qiye.163.com [59.111.176.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 327481EEC4; Sun, 17 Apr 2022 06:53:27 -0700 (PDT) Received: from [192.168.3.48] (unknown [58.22.0.235]) by mail-m17657.qiye.163.com (Hmail) with ESMTPA id EBE122800B9; Sun, 17 Apr 2022 21:53:23 +0800 (CST) Message-ID: <5f13aa47-92cd-6c71-66f5-c5513a36b277@rock-chips.com> Date: Sun, 17 Apr 2022 21:53:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] dmaengine: pl330: Fix unbalanced runtime PM To: Vinod Koul Cc: Huibin Hong , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org References: <1648296988-45745-1-git-send-email-sugar.zhang@rock-chips.com> From: sugar zhang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgPGg8OCBgUHx5ZQUlOS1dZCBgUCR5ZQVlLVUtZV1 kWDxoPAgseWUFZKDYvK1lXWShZQUhPN1dZLVlBSVdZDwkaFQgSH1lBWRkfQ0xWTxoZTU9LGENOTU 5NVRMBExYaEhckFA4PWVdZFhoPEhUdFFlBWU9LSFVKSktISkxVS1kG X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6MC46GSo5ND0wLjcyPCkBSSwR HhMKCRlVSlVKTU5LSUtITUtPSEpDVTMWGhIXVQgOHBoJVQETGhUcOwkUGBBWGBMSCwhVGBQWRVlX WRILWUFZTkNVSUlVS1VJSE5ZV1kIAVlBT0xPSDcG X-HM-Tid: 0a8037ccb48bda03kuwsebe122800b9 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Hi Vinod, 在 2022/4/11 21:48, Vinod Koul 写道: > On 26-03-22, 20:16, Sugar Zhang wrote: >> 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 = true >> | pm_runtime_get >> pm_runtime_put(if active) | >> pch->active = false | >> | work_list empty >> | | >> | pm_runtime_put(force) > maybe unconditional is a better word than force here? okay, will do in v2. > >> | | >> >> At this point, it's unbalanced(1 get / 2 put). >> >> After this patch: >> >> DMA TERMINATE TASKLET ROUTINE >> | | >> | issue_pending >> | | >> | pch->active = true >> | pm_runtime_get >> pm_runtime_put(if active) | >> pch->active = 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 terminated transfers") >> commit ae43b3289186 ("ARM: 8202/1: dmaengine: pl330: Add runtime Power Management support v12") > That is not the right way for Fixes tag like this? Fixes: 5c9e6c2b2ba3 ("dmaengine: pl330: Fix runtime PM support for terminated transfers") Fixes: ae43b3289186 ("ARM: 8202/1: dmaengine: pl330: Add runtime Power Management 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 = true; >> + power_down = pch->active; >> pch->active = false; >> } else { >> /* Make sure the PL330 Channel thread is active */ >> -- >> 2.7.4 -- Best Regards! 张学广/Sugar 瑞芯微电子股份有限公司 Rockchip Electronics Co., Ltd.