From: Baruch Siach <baruch@tkos.co.il>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>,
Lee Jones <lee.jones@linaro.org>, Andy Gross <agross@kernel.org>,
Balaji Prakash J <bjagadee@codeaurora.org>,
Rob Herring <robh+dt@kernel.org>,
Robert Marko <robert.marko@sartura.hr>,
Kathiravan T <kathirav@codeaurora.org>,
linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 2/4] pwm: driver for qualcomm ipq6018 pwm block
Date: Mon, 26 Jul 2021 07:31:55 +0300 [thread overview]
Message-ID: <87czr5wv9g.fsf@tarshish> (raw)
In-Reply-To: <YP2u9Hz2/+av6JLG@yoga>
Hi Bjorn,
On Sun, Jul 25 2021, Bjorn Andersson wrote:
> On Thu 22 Jul 05:01 CDT 2021, Baruch Siach wrote:
>> + if (IS_ERR(pwm->clk))
>> + return dev_err_probe(dev, PTR_ERR(pwm->clk),
>> + "failed to get core clock");
>> +
>> + ret = clk_prepare_enable(pwm->clk);
>
> Not sure if Uwe asked you this already, but do you need to clock the
> supply even when the PWM isn't enabled?
I guess not. However, tracking clock enable/disable per PWM signal
complicates the code. We'd need to balance enables with matching
disables in the .remove callback. I'd prefer to leave that as room for
future optimization.
>> + if (ret)
>> + return dev_err_probe(dev, ret, "clock enable failed");
>> +
>> + pwm->chip.dev = dev;
>> + pwm->chip.ops = &ipq_pwm_ops;
>> + pwm->chip.npwm = 4;
>> +
>> + ret = pwmchip_add(&pwm->chip);
>
> Depending on above answer you may or may not have the need to ensure the
> ordering of clk_disable_unprepare() in the remove function.
According to Uwe pwmchip_remove() must precede clock disable:
https://lore.kernel.org/linux-arm-msm/20210714201839.kfyqcyvowekc4ejs@pengutronix.de/
How is that related to per PWM signal clock handling?
> Otherwise devm_pwmchip_add() would be nice here.
Thanks,
baruch
--
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next prev parent reply other threads:[~2021-07-26 4:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 10:01 [PATCH v6 1/4] arm64: dts: ipq6018: correct TCSR block area Baruch Siach
2021-07-22 10:01 ` [PATCH v6 2/4] pwm: driver for qualcomm ipq6018 pwm block Baruch Siach
2021-07-25 18:35 ` Bjorn Andersson
2021-07-26 4:31 ` Baruch Siach [this message]
2021-07-22 10:01 ` [PATCH v6 3/4] dt-bindings: pwm: add IPQ6018 binding Baruch Siach
2021-07-23 23:03 ` Rob Herring
2021-07-25 18:27 ` Bjorn Andersson
2021-07-26 4:08 ` Baruch Siach
2021-07-26 17:48 ` Bjorn Andersson
2021-07-26 20:38 ` Rob Herring
2021-07-22 10:01 ` [PATCH v6 4/4] arm64: dts: ipq6018: add pwm node Baruch Siach
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