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Tue, 27 Aug 2019 08:17:50 +0000 Received: from AM0PR04MB4481.eurprd04.prod.outlook.com ([fe80::5d98:e1f4:aa72:16b4]) by AM0PR04MB4481.eurprd04.prod.outlook.com ([fe80::5d98:e1f4:aa72:16b4%4]) with mapi id 15.20.2178.022; Tue, 27 Aug 2019 08:17:50 +0000 From: Peng Fan To: "mturquette@baylibre.com" , "sboyd@kernel.org" , "shawnguo@kernel.org" , "s.hauer@pengutronix.de" , "festevam@gmail.com" , Aisheng Dong Subject: [PATCH] clk: imx: lpcg: write twice when writing lpcg regs Thread-Topic: [PATCH] clk: imx: lpcg: write twice when writing lpcg regs Thread-Index: AQHVXK/qRNohGClvt0yC94cqOwkPUA== Date: Tue, 27 Aug 2019 08:17:50 +0000 Message-ID: <1566936978-28519-1-git-send-email-peng.fan@nxp.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: git-send-email 2.7.4 x-clientproxiedby: HK2PR02CA0143.apcprd02.prod.outlook.com (2603:1096:202:16::27) To AM0PR04MB4481.eurprd04.prod.outlook.com (2603:10a6:208:70::15) authentication-results: spf=none (sender IP is ) smtp.mailfrom=peng.fan@nxp.com; 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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 From: Peng Fan There is hardware issue that: The output clock the LPCG cell will not turn back on as expected, even though a read of the IPG registers in the LPCG indicates that the clock should be enabled. The software workaround is to write twice to enable the LPCG clock output. Signed-off-by: Peng Fan --- drivers/clk/imx/clk-lpcg-scu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/clk/imx/clk-lpcg-scu.c b/drivers/clk/imx/clk-lpcg-scu.c index a73a799fb777..7391d0668ec4 100644 --- a/drivers/clk/imx/clk-lpcg-scu.c +++ b/drivers/clk/imx/clk-lpcg-scu.c @@ -54,6 +54,11 @@ static int clk_lpcg_scu_enable(struct clk_hw *hw) reg |= val << clk->bit_idx; writel(reg, clk->reg); + /* + * There is hardware bug. When enabling the LPCG clock + * output, SW can write the enabling value twice + */ + writel(reg, clk->reg); spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags); @@ -71,6 +76,11 @@ static void clk_lpcg_scu_disable(struct clk_hw *hw) reg = readl_relaxed(clk->reg); reg &= ~(CLK_GATE_SCU_LPCG_MASK << clk->bit_idx); writel(reg, clk->reg); + /* + * There is hardware bug. When enabling the LPCG clock + * output, SW can write the enabling value twice + */ + writel(reg, clk->reg); spin_unlock_irqrestore(&imx_lpcg_scu_lock, flags); } -- 2.16.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel