linux-kernel - [PATCH] pwm: tiehrpwm: Update shadow register for disabling PWMs

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Message-ID: <20190312090846.29519-1-vigneshr@ti.com>
Date:   Tue, 12 Mar 2019 14:38:46 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     <linux-pwm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Christoph Vogtländer 
        <c.vogtlaender@...ma-surface-science.com>
Subject: [PATCH] pwm: tiehrpwm: Update shadow register for disabling PWMs

From: Christoph Vogtländer <c.vogtlaender@...ma-surface-science.com>

It must be made sure that immediate mode is not already set, when
modifying shadow register value in ehrpwm_pwm_disable(). Otherwise
modifications to the action-qualifier continuous S/W force
register(AQSFRC) will be done in the active register.
This may happen when both channels are being disabled. In this case,
only the first channel state will be recorded as disabled in the shadow
register. Later, when enabling the first channel again, the second
channel would be enabled as well. Setting RLDCSF to zero, first, ensures
that the shadow register is updated as desired.

Fixes: 38dabd91ff0b ("pwm: tiehrpwm: Fix disabling of output of PWMs")
Signed-off-by: Christoph Vogtländer <c.vogtlaender@...ma-surface-science.com>
[vigneshr@...com: Improve commit message]
Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
---
 drivers/pwm/pwm-tiehrpwm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
index f7b8a86fa5c5..ad4a40c0f27c 100644
--- a/drivers/pwm/pwm-tiehrpwm.c
+++ b/drivers/pwm/pwm-tiehrpwm.c
@@ -382,6 +382,8 @@ static void ehrpwm_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	}
 
 	/* Update shadow register first before modifying active register */
+	ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
+		      AQSFRC_RLDCSF_ZRO);
 	ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);
 	/*
 	 * Changes to immediate action on Action Qualifier. This puts
-- 
2.21.0