From nobody Sun Dec 22 05:24:51 2024 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 DD0FBC7EE23 for ; Fri, 26 May 2023 10:55:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242145AbjEZKzN (ORCPT ); Fri, 26 May 2023 06:55:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229978AbjEZKzK (ORCPT ); Fri, 26 May 2023 06:55:10 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63EA7F7; Fri, 26 May 2023 03:55:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1685098509; x=1716634509; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=gsACS33QqbMepIsxf09vMS4nFee3rE52HroENxd1Rt4=; b=KlQSrhS7Pu5r4Ojt79iRpGYe7Y+93C9EVAINnOiNy+O3qOSipPyurDnD OEVKdfysKjUT2lqtf6Ocu3YW6QOMLcAmE99SA2hCwUPDnfklc4R5A00wf Y9FpzeFm2Erm7yRCk4ecRHzt+kNrU0tA6vbkouAw/IhL4xLHM/twamHS7 uey1CpekNfJM5MSiKNfypeNwwar0vNutsr/sYEGyiDWX28yTlcidaqIe/ J8EHDNDcGPmPjfFUVVd+5JKM892cghSZ/3v2PXq31+Vk05DQ80FIuFmo0 J6K8GkeeaLrDqD9dn82GNLToCsX2pmTgelRuyA9llVX36JfPGv7ASgO1+ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10721"; a="353018168" X-IronPort-AV: E=Sophos;i="6.00,194,1681196400"; d="scan'208";a="353018168" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 May 2023 03:55:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10721"; a="655599733" X-IronPort-AV: E=Sophos;i="6.00,193,1681196400"; d="scan'208";a="655599733" Received: from eandrei-mobl5.ger.corp.intel.com (HELO ijarvine-MOBL2.ger.corp.intel.com) ([10.252.53.213]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 May 2023 03:55:05 -0700 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= To: linux-serial@vger.kernel.org, Vinod Koul , Robert Baldyga , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Richard Tresidder , stable@vger.kernel.org Subject: [PATCH] dmaengine: pl330: Return DMA_PAUSED when transaction is paused Date: Fri, 26 May 2023 13:54:34 +0300 Message-Id: <20230526105434.14959-1-ilpo.jarvinen@linux.intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pl330_pause() does not set anything to indicate paused condition which causes pl330_tx_status() to return DMA_IN_PROGRESS. This breaks 8250 DMA flush after the fix in commit 57e9af7831dc ("serial: 8250_dma: Fix DMA Rx rearm race"). The function comment for pl330_pause() claims pause is supported but resume is not which is enough for 8250 DMA flush to work as long as DMA status reports DMA_PAUSED when appropriate. Add PAUSED state for descriptor and mark BUSY descriptors with PAUSED in pl330_pause(). Return DMA_PAUSED from pl330_tx_status() when the descriptor is PAUSED. Reported-by: Richard Tresidder Tested-by: Richard Tresidder Fixes: 88987d2c7534 ("dmaengine: pl330: add DMA_PAUSE feature") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/linux-serial/f8a86ecd-64b1-573f-c2fa-59f54108= 3f1a@electromag.com.au/ Signed-off-by: Ilpo J=C3=A4rvinen --- $ diff -u <(git grep -l -e '\.device_pause' -e '->device_pause') <(git grep= -l DMA_PAUSED) ...tells there might a few other drivers which do not properly return DMA_PAUSED status despite having a pause function. drivers/dma/pl330.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 0d9257fbdfb0..daad25f2c498 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -403,6 +403,12 @@ enum desc_status { * of a channel can be BUSY at any time. */ BUSY, + /* + * Pause was called while descriptor was BUSY. Due to hardware + * limitations, only termination is possible for descriptors + * that have been paused. + */ + PAUSED, /* * Sitting on the channel work_list but xfer done * by PL330 core @@ -2041,7 +2047,7 @@ static inline void fill_queue(struct dma_pl330_chan *= pch) list_for_each_entry(desc, &pch->work_list, node) { =20 /* If already submitted */ - if (desc->status =3D=3D BUSY) + if (desc->status =3D=3D BUSY || desc->status =3D=3D PAUSED) continue; =20 ret =3D pl330_submit_req(pch->thread, desc); @@ -2326,6 +2332,7 @@ static int pl330_pause(struct dma_chan *chan) { struct dma_pl330_chan *pch =3D to_pchan(chan); struct pl330_dmac *pl330 =3D pch->dmac; + struct dma_pl330_desc *desc; unsigned long flags; =20 pm_runtime_get_sync(pl330->ddma.dev); @@ -2335,6 +2342,10 @@ static int pl330_pause(struct dma_chan *chan) _stop(pch->thread); spin_unlock(&pl330->lock); =20 + list_for_each_entry(desc, &pch->work_list, node) { + if (desc->status =3D=3D BUSY) + desc->status =3D PAUSED; + } spin_unlock_irqrestore(&pch->lock, flags); pm_runtime_mark_last_busy(pl330->ddma.dev); pm_runtime_put_autosuspend(pl330->ddma.dev); @@ -2425,7 +2436,7 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t c= ookie, else if (running && desc =3D=3D running) transferred =3D pl330_get_current_xferred_count(pch, desc); - else if (desc->status =3D=3D BUSY) + else if (desc->status =3D=3D BUSY || desc->status =3D=3D PAUSED) /* * Busy but not running means either just enqueued, * or finished and not yet marked done @@ -2442,6 +2453,9 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t c= ookie, case DONE: ret =3D DMA_COMPLETE; break; + case PAUSED: + ret =3D DMA_PAUSED; + break; case PREP: case BUSY: ret =3D DMA_IN_PROGRESS; --=20 2.30.2