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-rw-r--r--SOURCES/arm64-pwm-rockchip-Keep-enabled-PWMs-running-while-probing.patch141
1 files changed, 141 insertions, 0 deletions
diff --git a/SOURCES/arm64-pwm-rockchip-Keep-enabled-PWMs-running-while-probing.patch b/SOURCES/arm64-pwm-rockchip-Keep-enabled-PWMs-running-while-probing.patch
new file mode 100644
index 0000000..4bdb5cb
--- /dev/null
+++ b/SOURCES/arm64-pwm-rockchip-Keep-enabled-PWMs-running-while-probing.patch
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+From: Simon South <simon@simonsouth.net>
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+ lee.jones@linaro.org, heiko@sntech.de, linux-pwm@vger.kernel.org,
+ linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org
+Subject: [PATCH v2] pwm: rockchip: Keep enabled PWMs running while probing
+Date: Sat, 19 Sep 2020 15:33:06 -0400
+Message-Id: <20200919193306.1023-1-simon@simonsouth.net>
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+Following commit cfc4c189bc70 ("pwm: Read initial hardware state at
+request time") the Rockchip PWM driver can no longer assume a device's
+pwm_state structure has been populated after a call to pwmchip_add().
+Consequently, the test in rockchip_pwm_probe() intended to prevent the
+driver from stopping PWM devices already enabled by the bootloader no
+longer functions reliably and this can lead to the kernel hanging
+during startup, particularly on devices like the Pinebook Pro that use
+a PWM-controlled backlight for their display.
+
+Avoid this by querying the device directly at probe time to determine
+whether or not it is enabled.
+
+Fixes: cfc4c189bc70 ("pwm: Read initial hardware state at request time")
+Signed-off-by: Simon South <simon@simonsouth.net>
+Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+Reviewed-by: Heiko Stuebner <heiko@sntech.de>
+---
+ drivers/pwm/pwm-rockchip.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
+index eb8c9cb645a6..098e94335cb5 100644
+--- a/drivers/pwm/pwm-rockchip.c
++++ b/drivers/pwm/pwm-rockchip.c
+@@ -288,6 +288,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
+ const struct of_device_id *id;
+ struct rockchip_pwm_chip *pc;
+ struct resource *r;
++ u32 enable_conf, ctrl;
+ int ret, count;
+
+ id = of_match_device(rockchip_pwm_dt_ids, &pdev->dev);
+@@ -362,7 +363,9 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
+ }
+
+ /* Keep the PWM clk enabled if the PWM appears to be up and running. */
+- if (!pwm_is_enabled(pc->chip.pwms))
++ enable_conf = pc->data->enable_conf;
++ ctrl = readl_relaxed(pc->base + pc->data->regs.ctrl);
++ if ((ctrl & enable_conf) != enable_conf)
+ clk_disable(pc->clk);
+
+ return 0;