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Wed, 29 Jan 2020 16:36:39 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id E2FE7100039; Wed, 29 Jan 2020 16:36:38 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag3node2.st.com [10.75.127.8]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id D1E002BC7C2; Wed, 29 Jan 2020 16:36:38 +0100 (CET) Received: from localhost (10.75.127.46) by SFHDAG3NODE2.st.com (10.75.127.8) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Wed, 29 Jan 2020 16:36:38 +0100 From: Amelie Delaunay To: Vinod Koul , Dan Williams , Maxime Coquelin , Alexandre Torgue Subject: [PATCH 7/8] dmaengine: stm32-dma: fix sleeping function called from invalid context Date: Wed, 29 Jan 2020 16:36:27 +0100 Message-ID: <20200129153628.29329-8-amelie.delaunay@st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200129153628.29329-1-amelie.delaunay@st.com> References: <20200129153628.29329-1-amelie.delaunay@st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG8NODE2.st.com (10.75.127.23) To SFHDAG3NODE2.st.com (10.75.127.8) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-01-29_03:2020-01-28, 2020-01-29 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200129_073648_802486_328A3B8F X-CRM114-Status: GOOD ( 15.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Amelie Delaunay , linux-kernel@vger.kernel.org, Pierre-Yves MORDRET , dmaengine@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org This patch fixes BUG: sleeping function called from invalid context in stm32_dma_disable_chan function. The goal of this function is to force channel disable if it has not been disabled by hardware. This consists in clearing STM32_DMA_SCR_EN bit and read it as 0 to ensure the channel is well disabled and the last transfer is over. In previous implementation, the waiting loop was based on a do...while (1) with a call to cond_resched to give the scheduler a chance to run a higher priority process. But in some conditions, stm32_dma_disable_chan can be called while preemption is disabled, on a stm32_dma_stop call for example. So cond_resched must not be used. To avoid this, use readl_relaxed_poll_timeout_atomic to poll STM32_DMA_SCR_EN bit cleared. Signed-off-by: Amelie Delaunay --- drivers/dma/stm32-dma.c | 27 +++++++++------------------ 1 file changed, 9 insertions(+), 18 deletions(-) diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 01a2374ae03a..b585e11c2168 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -421,29 +422,19 @@ static void stm32_dma_irq_clear(struct stm32_dma_chan *chan, u32 flags) static int stm32_dma_disable_chan(struct stm32_dma_chan *chan) { struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan); - unsigned long timeout = jiffies + msecs_to_jiffies(5000); - u32 dma_scr, id; + u32 dma_scr, id, reg; id = chan->id; - dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id)); + reg = STM32_DMA_SCR(id); + dma_scr = stm32_dma_read(dmadev, reg); if (dma_scr & STM32_DMA_SCR_EN) { dma_scr &= ~STM32_DMA_SCR_EN; - stm32_dma_write(dmadev, STM32_DMA_SCR(id), dma_scr); - - do { - dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id)); - dma_scr &= STM32_DMA_SCR_EN; - if (!dma_scr) - break; - - if (time_after_eq(jiffies, timeout)) { - dev_err(chan2dev(chan), "%s: timeout!\n", - __func__); - return -EBUSY; - } - cond_resched(); - } while (1); + stm32_dma_write(dmadev, reg, dma_scr); + + return readl_relaxed_poll_timeout_atomic(dmadev->base + reg, + dma_scr, !(dma_scr & STM32_DMA_SCR_EN), + 10, 1000000); } return 0; -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel