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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1F43ACD13DA for ; Tue, 5 May 2026 05:29:40 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4g8nBp4Grmz2xSF; Tue, 05 May 2026 15:29:38 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=172.234.252.31 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1777958978; cv=none; b=htpylrsrfZJB/vEGSRPpEScRS8eQsJ5Bx8ljlAN/us3craAPYg4gkA3VDxcr0CpfyTlpOfuyB18qVt5g2B4nBuBX499gL8ai3c6aCJ3fdNdeqL1MAn4M+9WRkFQRHOoKw7GeoDGmY8+dezYu4GeU+CLYpswExOpK5qw0nuhzGJr5kpq7Rt7op4tgyUsqMeffmg4ZclBw9Yog0tYBcew9a/89XCvv5AZicBfuaSo7a7eYHPhewBzukZb7Ja53dFBKWqtawVbr2NRpDkYuSszyDiSGe+7V2VpBQBjzkg06Xy6R587TexmH1GAs0HG/hEqiDGrUDSyXKjCgVuHf79Xisw== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1777958978; c=relaxed/relaxed; bh=CUqTdyw/9MDsz822GDLgEfvwtq7um/5il5KpWBnrMKo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=V4i6kGLzWsUX4QVcj29VQCF3T9vs4dtJpFtFkdBP+fKnysqjuLSnB5QhWSP9qn5Ym/mBhtKthLtVqy1gDMDlvFr2ZFY8vDWj6ZUE61UHBNR2LefvpHVGZ16ovcfN3qQjdMDXWtHs84MtuXE62fjbor9U1ZXOYGcl5vWylW+IigTCHOrRhDerkVNFXR4I0I2uWaJtP789e51tZ4tCOXicZmb3m+jnLytWgFPEaMxxyuVaExL9yM2wxkx6UnHhFxSvMpM32uxfzgOZ0Dp/sjV5kN0zjCoFa6eG8D6/4d5JzH7z6f9+3COzOm7ml4oSA23QU5dKmkkx657NV2BiHWcPng== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=hpzC+qsQ; dkim-atps=neutral; spf=pass (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=chleroy@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=hpzC+qsQ; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=chleroy@kernel.org; receiver=lists.ozlabs.org) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4g8nBn4w0Mz2xMV for ; Tue, 05 May 2026 15:29:37 +1000 (AEST) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 6792B41725; Tue, 5 May 2026 05:29:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F720C2BCB4; Tue, 5 May 2026 05:29:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777958974; bh=4fHxp8Q3woesOCXXrtJkOcW34n60i9kmwv85rTk8Mm8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hpzC+qsQ/qpsgVzgGx6hDiGsj/wjF5kCtTo22kPAr8nH+vEXKi7AX4ScKH6rB5/sV wzsqtRrtaJKC7cEmm7dOajyTY0kRcixWmUI9s/UWADXdG3IZVjZQI43rwUPU45Q9Ns uv/bA7I3mj1wIT5drWOmqU+9RSJRa1fuaSHCENdOgfq6qp5eILS5HX40n+LacV1B57 DQcd/GMjr9IMk5dnmHSwW5753uXFsu2jdPOCSuhDf/sPdn/NmLkXpgxPP/Z12u7Zt2 ypNvbNtleQxHs/d0gMPI4ky3YEKKPmKD5SnxjQ2/bmCIQ9CX6oZ393QuySthSJGG2W ucPMbBe7heS2g== Message-ID: Date: Tue, 5 May 2026 07:29:29 +0200 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net: wan: fsl_uhdlc_hdlc: fix dma_rmb usage in hdlc_rx_done To: Holger Brunck , netdev@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, andrew+netdev@lunn.ch, qiang.zhao@nxp.com, horms@kernel.org References: <20260504155642.2216040-1-holger.brunck@hitachienergy.com> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20260504155642.2216040-1-holger.brunck@hitachienergy.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, Le 04/05/2026 à 17:56, Holger Brunck a écrit : > If dma_rmb is used it has to be done after reading bd_status and checking > if R_E_S is zero. Therefore we need to move it into the while loop. Can you give more details ? Why does dma_rmb() has to be done after reading bd_status and checking if R_E_S is zero ? > > Fixes: c19b6d246a35 ("drivers/net: support hdlc function for QE-UCC") > Signed-off-by: Holger Brunck > --- > drivers/net/wan/fsl_ucc_hdlc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/net/wan/fsl_ucc_hdlc.c b/drivers/net/wan/fsl_ucc_hdlc.c > index 15bfb78381d4..09081f128a98 100644 > --- a/drivers/net/wan/fsl_ucc_hdlc.c > +++ b/drivers/net/wan/fsl_ucc_hdlc.c > @@ -523,12 +523,12 @@ static int hdlc_rx_done(struct ucc_hdlc_private *priv, int rx_work_limit) > u16 length, howmany = 0; > u8 *bdbuffer; > > - dma_rmb(); > bd = priv->currx_bd; > bd_status = be16_to_cpu(bd->status); > > /* while there are received buffers and BD is full (~R_E) */ > while (!((bd_status & (R_E_S)) || (--rx_work_limit < 0))) { > + dma_rmb(); > if (bd_status & (RX_BD_ERRORS)) { > dev->stats.rx_errors++; > > @@ -610,7 +610,6 @@ static int hdlc_rx_done(struct ucc_hdlc_private *priv, int rx_work_limit) > > bd_status = be16_to_cpu(bd->status); > } > - dma_rmb(); > > priv->currx_bd = bd; > return howmany;