From nobody Fri Jan 2 15:47:35 2026 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 3238DCD98FD for ; Wed, 11 Oct 2023 08:12:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230172AbjJKIMy (ORCPT ); Wed, 11 Oct 2023 04:12:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230255AbjJKIMn (ORCPT ); Wed, 11 Oct 2023 04:12:43 -0400 Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::228]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A131DA; Wed, 11 Oct 2023 01:12:39 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 475771BF20C; Wed, 11 Oct 2023 08:12:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1697011957; 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=raWpLxdnCsHiI6FQxGeq5/CW+Sjk7JXPZqqzsnU681g=; b=PdEzs+iwrBvoWBhPl97FjcpSGd90nBOEQ8xvaPJqFZ7EOnP3oVIei7hBWoOahPXkZiKoSx /eo7W0Bmiqth0V+eQESnoaYF7oZto0U9u57kkZUbon7wRGWnWbTk0pHou76+4tyfhmNHrj slmPP7CUxxKEsbcOPACjFRkqSdF4UPyK8sTNxvzqA9bz3z4olqOPb8rjmHMOj6vy5OE2WJ yRBPuUOe/3ahekYliDRdH3flj9EfuntbpXPyz+p2Prp4Mw/G3rf+BxjmZ8Zz+9GWcRjV+a RZBtCgCrdw7F14jdH3Eb9UmafuX+pLFOCM2lqm9xfacqRB7iwI0k/27CYO/ClA== From: Kory Maincent Date: Wed, 11 Oct 2023 10:11:45 +0200 Subject: [PATCH v3 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: <20231011-b4-feature_hdma_mainline-v3-6-24ee0c979c6f@bootlin.com> References: <20231011-b4-feature_hdma_mainline-v3-0-24ee0c979c6f@bootlin.com> In-Reply-To: <20231011-b4-feature_hdma_mainline-v3-0-24ee0c979c6f@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 0.12.3 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 can appears. In remote setup we can only use a readl to the memory to assured the full write has occurred. Fixes: 7e4b8a4fbe2c ("dmaengine: Add Synopsys eDMA IP version 0 support") Signed-off-by: Kory Maincent Reviewed-by: Serge Semin --- Changes in v2: - New patch --- 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