From nobody Tue Dec 30 11:08:21 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 6E77DC072A2 for ; Fri, 17 Nov 2023 10:04:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345864AbjKQKE2 (ORCPT ); Fri, 17 Nov 2023 05:04:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345810AbjKQKEO (ORCPT ); Fri, 17 Nov 2023 05:04:14 -0500 Received: from relay9-d.mail.gandi.net (relay9-d.mail.gandi.net [217.70.183.199]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ACFC7C5; Fri, 17 Nov 2023 02:04:10 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPSA id F0408FF80E; Fri, 17 Nov 2023 10:04:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1700215449; 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=NmKeLzmrWDgqwybx3yFMvQV6TVy/TJmLs+gOb6jsjkI=; b=ifWxZU5MoSMJa1RExPWzueMckAhDz+/FP9AYay2y7oLb+Zalg5OPxS+uJSZ6G4PLL7tG27 7B6Ezqo8uZROfk4rgCJc6dbvYgIY0+mmsg5++iTo+2fcRvuDlLaiwaAPAf0dyV1+8PobEE skGRJZEe1YrNGNOeLk6h94G5RCnogZx93R8UT/syiH7T0M9ZLWcTVt+xB67YQ+n6/3r0tV IGok0iY52aiynYO0qUXH50zKQ3zI/Qe6E8pLLQT4iH9YOGT69DmSBzVZnc2wkvYBBxQHs/ 4/1BS0mmd0dfRSU8bMiJBmTHfAEEK2aqW2EIlzEH2dGTFVoTpf8JR8kZfqoNKg== From: Kory Maincent Date: Fri, 17 Nov 2023 11:03:54 +0100 Subject: [PATCH v6 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: <20231117-b4-feature_hdma_mainline-v6-6-ebf7aa0e40d7@bootlin.com> References: <20231117-b4-feature_hdma_mainline-v6-0-ebf7aa0e40d7@bootlin.com> In-Reply-To: <20231117-b4-feature_hdma_mainline-v6-0-ebf7aa0e40d7@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 , Manivannan Sadhasivam 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 Reviewed-by: Manivannan Sadhasivam Signed-off-by: Kory Maincent --- Changes in v2: - New patch Changes in v4: - Update git commit message. Changes in v6: - Fix comment typos. --- 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..b75fdaffad9a 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 internal + * 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 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