From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C5D7329C57; Mon, 27 Oct 2025 19:07:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761592049; cv=none; b=q17r/TkAmA1CgEj5hVoGLWzbhbBmqOkdA73u7jWTKisG5aT2aSUjUg86xc5DfT8OM2w+VmjOfsX/FoqnHGHo9t0+759yqpB6BzDgeDDJ7Udu2aqaZqlwqMd2p3xZReJZfabrP7LEfqbqxx+ImJFs80QAhST9ZBhpcV7hVEw/dOI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761592049; c=relaxed/simple; bh=bfi4XgdljuuilD54HMwTBJlMsmDXGJan51+G/gNBQ1o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UToBy9sbfRlXIqr+DiJ8JHRS9mCv/6Ipb/iqID6s2hFZf4VmTLV6eUHyTWX3zlXFFrbjtKRGL64GPqH7mwfn9BF4wdwWhpWk4VnHIj6izMtM41grY40GStz+xzEe+GVyGmCX9WMfoQaJL4v8J3vgO+tkekVZplj8pA1iEyi65DE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=f7VgZ8JR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="f7VgZ8JR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22B22C4CEF1; Mon, 27 Oct 2025 19:07:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761592049; bh=bfi4XgdljuuilD54HMwTBJlMsmDXGJan51+G/gNBQ1o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f7VgZ8JRQEGKS6e4Ws7Fo1wBK6/jup5QO6C73CwzvFs3n9yfQSWEDbHnmEuu4l+rb yp7k4vLvw/4Uh1DK8+mNmkb0qXDKdfc9f8m810a5taQnB5GMuU/acQd2t+OOZyWAGM tj039czDEKYtu8ja66toNm1W4DIlXoBFTesS+EtA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fabrizio Castro , Lad Prabhakar , =?UTF-8?q?Niklas=20S=C3=B6derlund?= , Jakub Kicinski Subject: [PATCH 5.15 069/123] net: ravb: Ensure memory write completes before ringing TX doorbell Date: Mon, 27 Oct 2025 19:35:49 +0100 Message-ID: <20251027183448.244542050@linuxfoundation.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251027183446.381986645@linuxfoundation.org> References: <20251027183446.381986645@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lad Prabhakar commit 706136c5723626fcde8dd8f598a4dcd251e24927 upstream. Add a final dma_wmb() barrier before triggering the transmit request (TCCR_TSRQ) to ensure all descriptor and buffer writes are visible to the DMA engine. According to the hardware manual, a read-back operation is required before writing to the doorbell register to guarantee completion of previous writes. Instead of performing a dummy read, a dma_wmb() is used to both enforce the same ordering semantics on the CPU side and also to ensure completion of writes. Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper") Cc: stable@vger.kernel.org Co-developed-by: Fabrizio Castro Signed-off-by: Fabrizio Castro Signed-off-by: Lad Prabhakar Reviewed-by: Niklas Söderlund Link: https://patch.msgid.link/20251017151830.171062-5-prabhakar.mahadev-lad.rj@bp.renesas.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/renesas/ravb_main.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -1672,6 +1672,14 @@ static netdev_tx_t ravb_start_xmit(struc } else { desc->die_dt = DT_FSINGLE; } + + /* Before ringing the doorbell we need to make sure that the latest + * writes have been committed to memory, otherwise it could delay + * things until the doorbell is rang again. + * This is in replacement of the read operation mentioned in the HW + * manuals. + */ + dma_wmb(); ravb_modify(ndev, TCCR, TCCR_TSRQ0 << q, TCCR_TSRQ0 << q); priv->cur_tx[q] += num_tx_desc;