[PATCH v5 25/46] pwm: sti: avoid glitches on already running PWMs
From: Boris Brezillon <hidden>
Date: 2016-03-30 20:05:37
Also in:
dri-devel, intel-gfx, linux-arm-kernel, linux-clk, linux-fbdev, linux-leds, linux-pwm, linux-rockchip, linux-samsung-soc, lkml
Subsystem:
pwm subsystem, the rest · Maintainers:
Uwe Kleine-König, Linus Torvalds
The current logic will disable the PWM clk even if a PWM was left enabled by the bootloader (because it's controlling a critical device like a regulator for example). Keep the PWM clk enabled if at least one PWM is enabled to avoid any glitches. Signed-off-by: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> --- drivers/pwm/pwm-sti.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 0fbca94..bea1d17 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c@@ -343,7 +343,7 @@ static int sti_pwm_probe(struct platform_device *pdev) struct sti_pwm_compat_data *cdata; struct sti_pwm_chip *pc; struct resource *res; - int ret; + int i, ret; pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL); if (!pc)
@@ -394,7 +394,7 @@ static int sti_pwm_probe(struct platform_device *pdev) return -EINVAL; } - ret = clk_prepare(pc->clk); + ret = clk_prepare_enable(pc->clk); if (ret) { dev_err(dev, "failed to prepare clock\n"); return ret;
@@ -412,6 +412,19 @@ static int sti_pwm_probe(struct platform_device *pdev) return ret; } + /* + * Keep the PWM clk enabled if some PWMs appear to be up and + * running. + */ + for (i = 0; i < pc->chip.npwm; i++) { + struct pwm_state pstate; + + pwm_get_state(&pc->chip.pwms[i], &pstate); + if (pstate.enabled) + clk_enable(pc->clk); + } + clk_disable(pc->clk); + platform_set_drvdata(pdev, pc); return 0;
--
2.5.0