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Tue, 2 May 2023 06:50:25 +0000 (GMT) From: Jaewon Kim To: Krzysztof Kozlowski , Andi Shyti , Mark Brown , Alim Akhtar Cc: linux-spi@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Chanho Park , Jaewon Kim Subject: [PATCH v3 2/3] spi: s3c64xx: add sleep during transfer Date: Tue, 2 May 2023 15:28:12 +0900 Message-Id: <20230502062813.112434-3-jaewon02.kim@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230502062813.112434-1-jaewon02.kim@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrPKsWRmVeSWpSXmKPExsWy7bCmue7GTQEpBuemG1s8mLeNzWLxj+dM FlMfPmGzuLxf22JHwxFWi72vt7JbbHp8jdXi8q45bBYzzu9jsmj8eJPdgcvj+pJPzB6bVnWy edy5tofNY/OSeo++LasYPT5vkgtgi8q2yUhNTEktUkjNS85PycxLt1XyDo53jjc1MzDUNbS0 MFdSyEvMTbVVcvEJ0HXLzAE6TEmhLDGnFCgUkFhcrKRvZ1OUX1qSqpCRX1xiq5RakJJTYF6g V5yYW1yal66Xl1piZWhgYGQKVJiQnfH1cWzBQ66Kd0cXszYw3uPoYuTkkBAwkTj99zxzFyMX h5DADkaJ3Y93QTmfGCWO/OlkgXC+MUo0zHvGCNMy/9tJRojEXkaJGasboZyPjBLLbneDVbEJ aEt8X7+YFSQhIrCYUWLB1Z3sIA6zwA1Gie43m1lAqoQF7CWO3z4FZrMIqEqsvXqBCcTmFbCT WH1zNxPEPnmJ1RsOMIPYnED195pawKZKCNxjl7jR9xrqKBeJ849eskHYwhKvjm9hh7ClJD6/ 2wsVz5Zon/6HFcKukLi4YTZU3Fhi1rN2oDkcQNdpSqzfpQ9iSggoSxy5BXYaswCfRMfhv+wQ YV6JjjYhiEY1iftTz0ENkZGYdGQl1MUeEr8uzIAG3SRGiSUv1zBOYJSbhbBgASPjKkax1ILi 3PTUYqMCY3iUJefnbmIEpzwt9x2MM95+0DvEyMTBeIhRgoNZSYT3Q6FfihBvSmJlVWpRfnxR aU5q8SFGU2DYTWSWEk3OBybdvJJ4QxNLAxMzM0NzI1MDcyVxXmnbk8lCAumJJanZqakFqUUw fUwcnFINTNU9Saf/b1zL1dH5pHKyiPWeGfHvNxndeDRxx9YNCcEXtS54LVP/6voilJtXqqVE /yiHSiD7+aQSq0SpI3G7DDP9zdq3/9J72CdxQVsl6kIPx7sKJ47JC46F77l1TXXu1e8+PG8u vXm9dr/5wlvcDHtb13r5rWTew+IQcMhkich8yWt/Lp1QyNs+i+nZu8D3b+f6t7LWXJTdft9l yrzcM/6ffRzX33hgIFijKHLoi8C3NNeN9h7q2dM0rt9YVNI8NyHvozTntpJNTqdjWdfmas/3 r8+TydRY0FJ48/f+z6fNrSeGdLpyrrGXnWNjKS4rrqpXz2Js6nms48Tu7ld5EtME7vzcl3cu dtfGCYcbOpRYijMSDbWYi4oTAdSSxpgCBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrBLMWRmVeSWpSXmKPExsWy7bCSnO7GTQEpBn9eilo8mLeNzWLxj+dM FlMfPmGzuLxf22JHwxFWi72vt7JbbHp8jdXi8q45bBYzzu9jsmj8eJPdgcvj+pJPzB6bVnWy edy5tofNY/OSeo++LasYPT5vkgtgi+KySUnNySxLLdK3S+DK+Po4tuAhV8W7o4tZGxjvcXQx cnJICJhIzP92khHEFhLYzSix7HgpRFxGYvmzPjYIW1jifssRVoia94wSt2Yog9hsAtoS39cv BopzcYgILGWUeLznMQuIwyxwj1Hi5aRvTCBVwgL2Esdvn2IBsVkEVCXWXr0AFucVsJNYfXM3 E8QGeYnVGw4wg9icQPX3mlqgttlJXOn9yjqBkW8BI8MqRsnUguLc9NxiwwLDvNRyveLE3OLS vHS95PzcTYzgwNTS3MG4fdUHvUOMTByMhxglOJiVRHg/FPqlCPGmJFZWpRblxxeV5qQWH2KU 5mBREue90HUyXkggPbEkNTs1tSC1CCbLxMEp1cBUcVa10fXQJFaB/98DVeuyp68tW7VIT26m a4Tj/sZLcWFG7ju8DhaKut+xYP8+f7rg6+vZZ068eXPTIP30+7B0WcYmm508tx4n3Sg9+3vJ v7OL1LjnnHgzfxKjjtK9sMxFlWudptzdsaRY+gGPaJzMR5UwnYW3pFdsmJNW/s7u6R8ppfO6 kQUBR9sEtdsPVIk9/huwuCU05kjEPL2inkdVFk2PA7oXLxNS99J7npIS9+iRh4lwjP3ZxuIj K4pFRN90ernmiR8+PE+4ZsJenfQt738dvRkixf5a7JTRLo50ryKGjA2nzzuq28yq1FWft/+x pqfP0XeGD72Ddll07/+qvYjN0Fc+SFWmkq1KeoYSS3FGoqEWc1FxIgDX9jshuwIAAA== X-CMS-MailID: 20230502065025epcas2p11549db7400e6707c61bbb1cff1b22252 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20230502065025epcas2p11549db7400e6707c61bbb1cff1b22252 References: <20230502062813.112434-1-jaewon02.kim@samsung.com> X-Spam-Status: No, score=-4.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In polling mode, the status register is continuously read to check data transfer completion. It can cause excessive CPU usage. To reduce this, we can calculate the transfer time and put the sleep during transfer. When test on ExynosAuto9 SADK board, throughput remained the same, but 100% CPU utilization decreased to 40%. Signed-off-by: Jaewon Kim --- drivers/spi/spi-s3c64xx.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c index 66ac94022a1b..2a8304678df9 100644 --- a/drivers/spi/spi-s3c64xx.c +++ b/drivers/spi/spi-s3c64xx.c @@ -561,11 +561,18 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd, u32 cpy_len; u8 *buf; int ms; + unsigned long time_us; - /* millisecs to xfer 'len' bytes @ 'cur_speed' */ - ms = xfer->len * 8 * 1000 / sdd->cur_speed; + /* microsecs to xfer 'len' bytes @ 'cur_speed' */ + time_us = (xfer->len * 8 * 1000 * 1000) / sdd->cur_speed; + ms = (time_us / 1000); ms += 10; /* some tolerance */ + /* sleep during signal transfer time */ + status = readl(regs + S3C64XX_SPI_STATUS); + if (RX_FIFO_LVL(status, sdd) < xfer->len) + usleep_range(time_us / 2, time_us); + val = msecs_to_loops(ms); do { status = readl(regs + S3C64XX_SPI_STATUS); -- 2.17.1