From nobody Tue Dec 30 16:57:58 2025 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 85E85C4332F for ; Tue, 14 Nov 2023 14:52:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233598AbjKNOw1 (ORCPT ); Tue, 14 Nov 2023 09:52:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233497AbjKNOwL (ORCPT ); Tue, 14 Nov 2023 09:52:11 -0500 Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [217.70.183.193]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CAE1181; Tue, 14 Nov 2023 06:52:08 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 919E5240014; Tue, 14 Nov 2023 14:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1699973527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Njx3NaGKWu808jS2rM/MlNFciYIn5u1xCeEnktSSeyc=; b=o1u43gWsw//1Ii7k+NR1KGDSUTt45keYRcjX7yDasFcLfK3YLnvA4/JcEFfwjFKugypt3Y DHXBZo/jRAvoB2wHpDYYIkGkfH/sStZm3ChEUzHn4u30dt693atc/k8OBPUNBAcPpk5xXS l/NhE9sHEnS9fEvDKUUc2IsLI+WoYgh432PSGfLTHGIg+LU7Tuaf5xiD5ArJu2yEZ3xYJE lIfrMG7nuqyLyXcG8Qi0U7M2eJY/OUwRGEBbnscU68RJ5tojRSTAPLf7jntB0S+6W0Hhgc xXd1/YhidQ2FKLfiFJx4mLVPErCkU7dH/gRpLIy2OH8cs9L8eh81YrA/lgGuQQ== From: Kory Maincent Date: Tue, 14 Nov 2023 15:51:59 +0100 Subject: [PATCH v5 6/6] dmaengine: dw-edma: eDMA: Add sync read before starting the DMA transfer in remote setup MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20231114-b4-feature_hdma_mainline-v5-6-7bc86d83c6f7@bootlin.com> References: <20231114-b4-feature_hdma_mainline-v5-0-7bc86d83c6f7@bootlin.com> In-Reply-To: <20231114-b4-feature_hdma_mainline-v5-0-7bc86d83c6f7@bootlin.com> To: Manivannan Sadhasivam , Gustavo Pimentel , Serge Semin , Vinod Koul , Cai Huoqing Cc: Thomas Petazzoni , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Herve Codina , Kory Maincent X-Mailer: b4 0.12.4 X-GND-Sasl: kory.maincent@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The Linked list element and pointer are not stored in the same memory as the eDMA controller register. If the doorbell register is toggled before the full write of the linked list a race condition error will occur. In remote setup we can only use a readl to the memory to assure the full write has occurred. Fixes: 7e4b8a4fbe2c ("dmaengine: Add Synopsys eDMA IP version 0 support") Reviewed-by: Serge Semin Signed-off-by: Kory Maincent --- Changes in v2: - New patch Changes in v4: - Update git commit message. --- drivers/dma/dw-edma/dw-edma-v0-core.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw= -edma-v0-core.c index b38786f0ad79..6245b720fbfe 100644 --- a/drivers/dma/dw-edma/dw-edma-v0-core.c +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c @@ -346,6 +346,20 @@ static void dw_edma_v0_core_write_chunk(struct dw_edma= _chunk *chunk) dw_edma_v0_write_ll_link(chunk, i, control, chunk->ll_region.paddr); } =20 +static void dw_edma_v0_sync_ll_data(struct dw_edma_chunk *chunk) +{ + /* + * In case of remote eDMA engine setup, the DW PCIe RP/EP internals + * configuration registers and Application memory are normally accessed + * over different buses. Ensure LL-data reaches the memory before the + * doorbell register is toggled by issuing the dummy-read from the remote + * LL memory in a hope that the posted MRd TLP will return only after the + * last MWr TLP is completed + */ + if (!(chunk->chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL)) + readl(chunk->ll_region.vaddr.io); +} + static void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first) { struct dw_edma_chan *chan =3D chunk->chan; @@ -412,6 +426,9 @@ static void dw_edma_v0_core_start(struct dw_edma_chunk = *chunk, bool first) SET_CH_32(dw, chan->dir, chan->id, llp.msb, upper_32_bits(chunk->ll_region.paddr)); } + + dw_edma_v0_sync_ll_data(chunk); + /* Doorbell */ SET_RW_32(dw, chan->dir, doorbell, FIELD_PREP(EDMA_V0_DOORBELL_CH_MASK, chan->id)); --=20 2.25.1