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Thu, 24 Jun 2021 11:40:05 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 2D9AA100034; Thu, 24 Jun 2021 11:40:05 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 1377921B518; Thu, 24 Jun 2021 11:40:05 +0200 (CEST) Received: from localhost (10.75.127.47) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 24 Jun 2021 11:40:04 +0200 From: Amelie Delaunay To: Vinod Koul , Rob Herring , Dan Williams , Maxime Coquelin , Alexandre Torgue CC: , , , , , Amelie Delaunay , Pierre-Yves Mordret Subject: [PATCH 2/2] dmaengine: stm32-dma: add alternate REQ/ACK protocol management Date: Thu, 24 Jun 2021 11:39:59 +0200 Message-ID: <20210624093959.142265-3-amelie.delaunay@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210624093959.142265-1-amelie.delaunay@foss.st.com> References: <20210624093959.142265-1-amelie.delaunay@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.47] X-ClientProxiedBy: SFHDAG2NODE2.st.com (10.75.127.5) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-06-24_06:2021-06-24, 2021-06-24 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210624_024017_629113_4BFE72AF X-CRM114-Status: GOOD ( 17.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org STM32 USART/UART is not managing correctly the default DMA REQ/ACK protocol leading to possibly lock the DMA stream. Default protocol consists in maintaining ACK signal up to the removal of REQuest and the transfer completion. In case of alternative REQ/ACK protocol, ACK de-assertion does not wait the removal of the REQuest, but only the transfer completion. This patch retrieves the need of the alternative protocol through the device tree, and sets the protocol accordingly. It also unwrap STM32_DMA_DIRECT_MODE_GET macro definition for consistency with new STM32_DMA_ALT_ACK_MODE_GET macro definition. Signed-off-by: Amelie Delaunay --- drivers/dma/stm32-dma.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index f54ecb123a52..d3aa34b3d2f7 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -60,6 +60,7 @@ #define STM32_DMA_SCR_PSIZE_GET(n) ((n & STM32_DMA_SCR_PSIZE_MASK) >> 11) #define STM32_DMA_SCR_DIR_MASK GENMASK(7, 6) #define STM32_DMA_SCR_DIR(n) ((n & 0x3) << 6) +#define STM32_DMA_SCR_TRBUFF BIT(20) /* Bufferable transfer for USART/UART */ #define STM32_DMA_SCR_CT BIT(19) /* Target in double buffer */ #define STM32_DMA_SCR_DBM BIT(18) /* Double Buffer Mode */ #define STM32_DMA_SCR_PINCOS BIT(15) /* Peripheral inc offset size */ @@ -138,8 +139,9 @@ #define STM32_DMA_THRESHOLD_FTR_MASK GENMASK(1, 0) #define STM32_DMA_THRESHOLD_FTR_GET(n) ((n) & STM32_DMA_THRESHOLD_FTR_MASK) #define STM32_DMA_DIRECT_MODE_MASK BIT(2) -#define STM32_DMA_DIRECT_MODE_GET(n) (((n) & STM32_DMA_DIRECT_MODE_MASK) \ - >> 2) +#define STM32_DMA_DIRECT_MODE_GET(n) (((n) & STM32_DMA_DIRECT_MODE_MASK) >> 2) +#define STM32_DMA_ALT_ACK_MODE_MASK BIT(4) +#define STM32_DMA_ALT_ACK_MODE_GET(n) (((n) & STM32_DMA_ALT_ACK_MODE_MASK) >> 4) enum stm32_dma_width { STM32_DMA_BYTE, @@ -1252,6 +1254,8 @@ static void stm32_dma_set_config(struct stm32_dma_chan *chan, chan->threshold = STM32_DMA_THRESHOLD_FTR_GET(cfg->features); if (STM32_DMA_DIRECT_MODE_GET(cfg->features)) chan->threshold = STM32_DMA_FIFO_THRESHOLD_NONE; + if (STM32_DMA_ALT_ACK_MODE_GET(cfg->features)) + chan->chan_reg.dma_scr |= STM32_DMA_SCR_TRBUFF; } static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,