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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 A82C1C4332D for ; Mon, 28 Dec 2020 15:53:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C3C5206E5 for ; Mon, 28 Dec 2020 15:53:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391889AbgL1Nlo (ORCPT ); Mon, 28 Dec 2020 08:41:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:40964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391503AbgL1Nk7 (ORCPT ); Mon, 28 Dec 2020 08:40:59 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 26C372072C; Mon, 28 Dec 2020 13:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609162843; bh=/1BgyCRqNzKFlvH0mGpObww8XwPPjHndLuaSHWsrnjQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=x4TLvKGls9O0X9CVhMYn5L2hq4bCbNliMLkBDRi4EOE4jWlrL29hM8RgD3nb6pkM6 IOHUbjfgu12un5CAZIIg2LevD7SKYHydDKDJoYYYrkh5FoSviqDEOVa+z1P/91zmQV S1wkHUQRmdDSLuKQFoKzyPJrkrtMOBM+QApF3AjE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Douglas Anderson , Stephen Boyd , Akash Asthana , Dmitry Baryshkov , Bjorn Andersson , Sasha Levin Subject: [PATCH 5.4 081/453] soc: qcom: geni: More properly switch to DMA mode Date: Mon, 28 Dec 2020 13:45:17 +0100 Message-Id: <20201228124941.136622187@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124937.240114599@linuxfoundation.org> References: <20201228124937.240114599@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: Douglas Anderson [ Upstream commit 4b6ea87be44ef34732846fc71e44c41125f0c4fa ] On geni-i2c transfers using DMA, it was seen that if you program the command (I2C_READ) before calling geni_se_rx_dma_prep() that it could cause interrupts to fire. If we get unlucky, these interrupts can just keep firing (and not be handled) blocking further progress and hanging the system. In commit 02b9aec59243 ("i2c: i2c-qcom-geni: Fix DMA transfer race") we avoided that by making sure we didn't program the command until after geni_se_rx_dma_prep() was called. While that avoided the problems, it also turns out to be invalid. At least in the TX case we started seeing sporadic corrupted transfers. This is easily seen by adding an msleep() between the DMA prep and the writing of the command, which makes the problem worse. That means we need to revert that commit and find another way to fix the bogus IRQs. Specifically, after reverting commit 02b9aec59243 ("i2c: i2c-qcom-geni: Fix DMA transfer race"), I put some traces in. I found that the when the interrupts were firing like crazy: - "m_stat" had bits for M_RX_IRQ_EN, M_RX_FIFO_WATERMARK_EN set. - "dma" was set. Further debugging showed that I could make the problem happen more reliably by adding an "msleep(1)" any time after geni_se_setup_m_cmd() ran up until geni_se_rx_dma_prep() programmed the length. A rather simple fix is to change geni_se_select_dma_mode() so it's a true inverse of geni_se_select_fifo_mode() and disables all the FIFO related interrupts. Now the problematic interrupts can't fire and we can program things in the correct order without worrying. As part of this, let's also change the writel_relaxed() in the prepare function to a writel() so that our DMA is guaranteed to be prepared now that we can't rely on geni_se_setup_m_cmd()'s writel(). NOTE: the only current user of GENI_SE_DMA in mainline is i2c. Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller") Fixes: 02b9aec59243 ("i2c: i2c-qcom-geni: Fix DMA transfer race") Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd Reviewed-by: Akash Asthana Tested-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20201013142448.v2.1.Ifdb1b69fa3367b81118e16e9e4e63299980ca798@changeid Signed-off-by: Bjorn Andersson Signed-off-by: Sasha Levin --- drivers/soc/qcom/qcom-geni-se.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c index 7d622ea1274eb..2e66098e82975 100644 --- a/drivers/soc/qcom/qcom-geni-se.c +++ b/drivers/soc/qcom/qcom-geni-se.c @@ -282,10 +282,23 @@ static void geni_se_select_fifo_mode(struct geni_se *se) static void geni_se_select_dma_mode(struct geni_se *se) { + u32 proto = geni_se_read_proto(se); u32 val; geni_se_irq_clear(se); + val = readl_relaxed(se->base + SE_GENI_M_IRQ_EN); + if (proto != GENI_SE_UART) { + val &= ~(M_CMD_DONE_EN | M_TX_FIFO_WATERMARK_EN); + val &= ~(M_RX_FIFO_WATERMARK_EN | M_RX_FIFO_LAST_EN); + } + writel_relaxed(val, se->base + SE_GENI_M_IRQ_EN); + + val = readl_relaxed(se->base + SE_GENI_S_IRQ_EN); + if (proto != GENI_SE_UART) + val &= ~S_CMD_DONE_EN; + writel_relaxed(val, se->base + SE_GENI_S_IRQ_EN); + val = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN); val |= GENI_DMA_MODE_EN; writel_relaxed(val, se->base + SE_GENI_DMA_MODE_EN); @@ -644,7 +657,7 @@ int geni_se_tx_dma_prep(struct geni_se *se, void *buf, size_t len, writel_relaxed(lower_32_bits(*iova), se->base + SE_DMA_TX_PTR_L); writel_relaxed(upper_32_bits(*iova), se->base + SE_DMA_TX_PTR_H); writel_relaxed(GENI_SE_DMA_EOT_BUF, se->base + SE_DMA_TX_ATTR); - writel_relaxed(len, se->base + SE_DMA_TX_LEN); + writel(len, se->base + SE_DMA_TX_LEN); return 0; } EXPORT_SYMBOL(geni_se_tx_dma_prep); @@ -681,7 +694,7 @@ int geni_se_rx_dma_prep(struct geni_se *se, void *buf, size_t len, writel_relaxed(upper_32_bits(*iova), se->base + SE_DMA_RX_PTR_H); /* RX does not have EOT buffer type bit. So just reset RX_ATTR */ writel_relaxed(0, se->base + SE_DMA_RX_ATTR); - writel_relaxed(len, se->base + SE_DMA_RX_LEN); + writel(len, se->base + SE_DMA_RX_LEN); return 0; } EXPORT_SYMBOL(geni_se_rx_dma_prep); -- 2.27.0