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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A769EC55178 for ; Tue, 27 Oct 2020 16:10:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6676120829 for ; Tue, 27 Oct 2020 16:10:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603815029; bh=eilhextZQwZykMlBpE0UMAvzHMeZHW5aESsHenSw0qo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jGpDjSZJJUNfxgfqfX4gYdOajD8t446lunE65WwqBgu3srG0D72xtbl5Vo9aI9kXD UaB96t4wNZmLz8TAbpSOxcFkG0hxQPdZcfczN3vC3/uqGUMlY6t84Ge//kobhtL6/Z /soMPDxxViAwGTIFj/gVsrrMpbhU4ao6PpRZbbKk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1807420AbgJ0QK1 (ORCPT ); Tue, 27 Oct 2020 12:10:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:55122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1803735AbgJ0PxX (ORCPT ); Tue, 27 Oct 2020 11:53:23 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 968E220657; Tue, 27 Oct 2020 15:53:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603814003; bh=eilhextZQwZykMlBpE0UMAvzHMeZHW5aESsHenSw0qo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ISxv544LZi7cD0zOyxHWq2Gs8418pbSGm4W8jGKThROYaIMcHcIw6nkDF/UOTi/Yk juMSdRJcQgPyo2VoqKO1ralOUFx/LHJUAkKUAO4/FhYVhafh7jkCn5vdKh3M7sA8AF 5ti+XgRz01flgrsou1Q7yv8G9a7os4xU3tB4p5TM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Serge Semin , Vinod Koul , Sasha Levin Subject: [PATCH 5.9 742/757] dmaengine: dw: Add DMA-channels mask cell support Date: Tue, 27 Oct 2020 14:56:32 +0100 Message-Id: <20201027135525.309374373@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135450.497324313@linuxfoundation.org> References: <20201027135450.497324313@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Serge Semin [ Upstream commit e8ee6c8cb61b676f1a2d6b942329e98224bd8ee9 ] DW DMA IP-core provides a way to synthesize the DMA controller with channels having different parameters like maximum burst-length, multi-block support, maximum data width, etc. Those parameters both explicitly and implicitly affect the channels performance. Since DMA slave devices might be very demanding to the DMA performance, let's provide a functionality for the slaves to be assigned with DW DMA channels, which performance according to the platform engineer fulfill their requirements. After this patch is applied it can be done by passing the mask of suitable DMA-channels either directly in the dw_dma_slave structure instance or as a fifth cell of the DMA DT-property. If mask is zero or not provided, then there is no limitation on the channels allocation. For instance Baikal-T1 SoC is equipped with a DW DMAC engine, which first two channels are synthesized with max burst length of 16, while the rest of the channels have been created with max-burst-len=4. It would seem that the first two channels must be faster than the others and should be more preferable for the time-critical DMA slave devices. In practice it turned out that the situation is quite the opposite. The channels with max-burst-len=4 demonstrated a better performance than the channels with max-burst-len=16 even when they both had been initialized with the same settings. The performance drop of the first two DMA-channels made them unsuitable for the DW APB SSI slave device. No matter what settings they are configured with, full-duplex SPI transfers occasionally experience the Rx FIFO overflow. It means that the DMA-engine doesn't keep up with incoming data pace even though the SPI-bus is enabled with speed of 25MHz while the DW DMA controller is clocked with 50MHz signal. There is no such problem has been noticed for the channels synthesized with max-burst-len=4. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20200731200826.9292-6-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/dw/core.c | 4 ++++ drivers/dma/dw/of.c | 7 +++++-- include/linux/platform_data/dma-dw.h | 2 ++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c index 4700f2e87a627..d9333ee14527e 100644 --- a/drivers/dma/dw/core.c +++ b/drivers/dma/dw/core.c @@ -772,6 +772,10 @@ bool dw_dma_filter(struct dma_chan *chan, void *param) if (dws->dma_dev != chan->device->dev) return false; + /* permit channels in accordance with the channels mask */ + if (dws->channels && !(dws->channels & dwc->mask)) + return false; + /* We have to copy data since dws can be temporary storage */ memcpy(&dwc->dws, dws, sizeof(struct dw_dma_slave)); diff --git a/drivers/dma/dw/of.c b/drivers/dma/dw/of.c index 1474b3817ef4f..c1cf7675b9d10 100644 --- a/drivers/dma/dw/of.c +++ b/drivers/dma/dw/of.c @@ -22,18 +22,21 @@ static struct dma_chan *dw_dma_of_xlate(struct of_phandle_args *dma_spec, }; dma_cap_mask_t cap; - if (dma_spec->args_count != 3) + if (dma_spec->args_count < 3 || dma_spec->args_count > 4) return NULL; slave.src_id = dma_spec->args[0]; slave.dst_id = dma_spec->args[0]; slave.m_master = dma_spec->args[1]; slave.p_master = dma_spec->args[2]; + if (dma_spec->args_count >= 4) + slave.channels = dma_spec->args[3]; if (WARN_ON(slave.src_id >= DW_DMA_MAX_NR_REQUESTS || slave.dst_id >= DW_DMA_MAX_NR_REQUESTS || slave.m_master >= dw->pdata->nr_masters || - slave.p_master >= dw->pdata->nr_masters)) + slave.p_master >= dw->pdata->nr_masters || + slave.channels >= BIT(dw->pdata->nr_channels))) return NULL; dma_cap_zero(cap); diff --git a/include/linux/platform_data/dma-dw.h b/include/linux/platform_data/dma-dw.h index fbbeb2f6189b8..b34a094b2258d 100644 --- a/include/linux/platform_data/dma-dw.h +++ b/include/linux/platform_data/dma-dw.h @@ -26,6 +26,7 @@ struct device; * @dst_id: dst request line * @m_master: memory master for transfers on allocated channel * @p_master: peripheral master for transfers on allocated channel + * @channels: mask of the channels permitted for allocation (zero value means any) * @hs_polarity:set active low polarity of handshake interface */ struct dw_dma_slave { @@ -34,6 +35,7 @@ struct dw_dma_slave { u8 dst_id; u8 m_master; u8 p_master; + u8 channels; bool hs_polarity; }; -- 2.25.1