The patch below does not apply to the 5.3-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b234fe9558615098d8d62516e7041ad7f99ebcea Mon Sep 17 00:00:00 2001

From: Leonard Crestez leonard.crestez@nxp.com Date: Tue, 22 Oct 2019 22:21:28 +0300 Subject: [PATCH] clk: imx8m: Use SYS_PLL1_800M as intermediate parent of CLK_ARM

During cpu frequency switching the main "CLK_ARM" is reparented to an intermediate "step" clock. On imx8mm and imx8mn the 24M oscillator is used for this purpose but it is extremely slow, increasing wakeup latencies to the point that i2c transactions can timeout and system becomes unresponsive.

Fix by switching the "step" clk to SYS_PLL1_800M, matching the behavior of imx8m cpufreq drivers in imx vendor tree.

This bug was not immediately apparent because upstream arm64 defconfig uses the "performance" governor by default so no cpufreq transitions happen.

Fixes: ba5625c3e272 ("clk: imx: Add clock driver support for imx8mm") Fixes: 96d6392b54db ("clk: imx: Add support for i.MX8MN clock driver")

Cc: stable@vger.kernel.org Signed-off-by: Leonard Crestez leonard.crestez@nxp.com Link: https://lkml.kernel.org/r/f5d2b9c53f1ed5ccb1dd3c6624f56759d92e1689.157177177... Acked-by: Shawn Guo shawnguo@kernel.org Signed-off-by: Stephen Boyd sboyd@kernel.org

diff --git a/drivers/clk/imx/clk-imx8mm.c b/drivers/clk/imx/clk-imx8mm.c index 067ab876911d..172589e94f60 100644 --- a/drivers/clk/imx/clk-imx8mm.c +++ b/drivers/clk/imx/clk-imx8mm.c @@ -638,7 +638,7 @@ static int imx8mm_clocks_probe(struct platform_device *pdev) clks[IMX8MM_CLK_A53_DIV], clks[IMX8MM_CLK_A53_SRC], clks[IMX8MM_ARM_PLL_OUT], - clks[IMX8MM_CLK_24M]); + clks[IMX8MM_SYS_PLL1_800M]);

imx_check_clocks(clks, ARRAY_SIZE(clks));

diff --git a/drivers/clk/imx/clk-imx8mn.c b/drivers/clk/imx/clk-imx8mn.c index 47a4b44ba3cb..58b5acee3830 100644 --- a/drivers/clk/imx/clk-imx8mn.c +++ b/drivers/clk/imx/clk-imx8mn.c @@ -610,7 +610,7 @@ static int imx8mn_clocks_probe(struct platform_device *pdev) clks[IMX8MN_CLK_A53_DIV], clks[IMX8MN_CLK_A53_SRC], clks[IMX8MN_ARM_PLL_OUT], - clks[IMX8MN_CLK_24M]); + clks[IMX8MN_SYS_PLL1_800M]);

imx_check_clocks(clks, ARRAY_SIZE(clks));