From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relmlor1.renesas.com ([210.160.252.171]:12374 "EHLO relmlie5.idc.renesas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725967AbeLGIcD (ORCPT ); Fri, 7 Dec 2018 03:32:03 -0500 From: Yoshihiro Shimoda To: thierry.reding@gmail.com Cc: linux-pwm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Yoshihiro Shimoda Subject: [PATCH 5/5] pwm: rcar: add workaround to output "pseudo" low level Date: Fri, 7 Dec 2018 17:29:33 +0900 Message-Id: <1544171373-29618-6-git-send-email-yoshihiro.shimoda.uh@renesas.com> In-Reply-To: <1544171373-29618-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> References: <1544171373-29618-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: This PWM Timer cannot output low because setting 0x000 is prohibited on PWMCNT.PH0 (High-Level Period) bitfields. So, avoiding the prohibited, this patch adds a workaround function to change the value from 0 to 1 as pseudo low level. Signed-off-by: Yoshihiro Shimoda --- drivers/pwm/pwm-rcar.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c index e479b6a..888cb37 100644 --- a/drivers/pwm/pwm-rcar.c +++ b/drivers/pwm/pwm-rcar.c @@ -166,6 +166,20 @@ static void rcar_pwm_disable(struct rcar_pwm_chip *rp) rcar_pwm_update(rp, RCAR_PWMCR_EN0, 0, RCAR_PWMCR); } +static void rcar_pwm_workaround_output_low(struct rcar_pwm_chip *rp) +{ + /* + * This PWM Timer cannot output low because setting 0x000 is + * prohibited on PWMCNT.PH0 (High-Level Period) bitfields. So, avoiding + * the prohibited, this function changes the value from 0 to 1 as + * pseudo low level. + * + * TODO: Add GPIO handling to output low level. + */ + if ((rp->pwmcnt & RCAR_PWMCNT_PH0_MASK) == 0) + rp->pwmcnt |= 1; +} + static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { @@ -179,6 +193,7 @@ static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR); rcar_pwm_calc_counter(rp, div, state->duty_cycle, state->period); + rcar_pwm_workaround_output_low(rp); ret = rcar_pwm_set_counter(rp); if (!ret) rcar_pwm_set_clock_control(rp, div); -- 1.9.1