linux-kernel - Re: [PATCH V4] mmc: sdhci-msm: Reset GCC_SDCC

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Date:   Thu, 21 Apr 2022 11:56:01 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     "Sajida Bhanu (Temp)" <quic_c_sbhanu@...cinc.com>,
        adrian.hunter@...el.com, agross@...nel.org,
        bjorn.andersson@...aro.org, ulf.hansson@...aro.org,
        chris@...ntf.net, venkatg@...eaurora.org, gdjakov@...sol.com,
        quic_asutoshd@...cinc.com
Cc:     linux-mmc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_rampraka@...cinc.com,
        quic_pragalla@...cinc.com, quic_sartgarg@...cinc.com,
        quic_nitirawa@...cinc.com, quic_sayalil@...cinc.com
Subject: Re: [PATCH V4] mmc: sdhci-msm: Reset GCC_SDCC_BCR register for SDHC

On Do, 2022-04-21 at 10:32 +0530, Sajida Bhanu (Temp) wrote:
> Hi,
> 
> Thanks for the review.
> 
> Please find the inline comments.
> 
> Thanks,
> 
> Sajida
> 
> On 4/19/2022 12:52 PM, Philipp Zabel wrote:
> > Hi Sajida,
> > 
> > On Di, 2022-04-19 at 11:46 +0530, Sajida Bhanu (Temp) wrote:
> > [...]
> > > > > +static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
> > > > > +{
> > > > > +	struct reset_control *reset;
> > > > > +	int ret = 0;
> > > > No need to initialize ret.
> > > > 
> > > > > +
> > > > > +	reset = reset_control_get_optional_exclusive(dev, NULL);
> > > > > +	if (IS_ERR(reset))
> > > > > +		return dev_err_probe(dev, PTR_ERR(reset),
> > > > > +				"unable to acquire core_reset\n");
> > > > > +
> > > > > +	if (!reset)
> > > > > +		return ret;
> > > Here we are returning ret directly if reset is NULL , so ret
> > > initialization is required.
> > You are right. I would just "return 0;" here, but this is correct as
> > is.
> Ok
> > > > > +
> > > > > +	ret = reset_control_assert(reset);
> > > > > +	if (ret)
> > > > > +		return dev_err_probe(dev, ret, "core_reset assert failed\n");
> > > > Missing reset_control_put(reset) in the error path.
> > > Sure will add
> > > > > +
> > > > > +	/*
> > > > > +	 * The hardware requirement for delay between assert/deassert
> > > > > +	 * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
> > > > > +	 * ~125us (4/32768). To be on the safe side add 200us delay.
> > > > > +	 */
> > > > > +	usleep_range(200, 210);
> > > > > +
> > > > > +	ret = reset_control_deassert(reset);
> > > > > +	if (ret)
> > > > > +		return dev_err_probe(dev, ret, "core_reset deassert failed\n");
> > > > Same as above. Maybe make both ret = dev_err_probe() and goto ...
> > > In both cases error message is different so I think goto not good idea here.
> > You could goto after the error message. Either way is fine.
> 
> Sorry didn't get this ..can  you please help

I meant you could either use goto after the error messages:

+static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
+{
[...]
+	ret = reset_control_assert(reset);
+	if (ret) {
+		dev_err_probe(dev, ret, "core_reset assert failed\n");
+		goto out_reset_put;
+	}
[...]
+	ret = reset_control_deassert(reset);
+	if (ret) {
+		dev_err_probe(dev, ret, "core_reset deassert failed\n");
+		goto out_reset_put;
+	}
+
+	usleep_range(200, 210);
+
+out_reset_put:
+	reset_control_put(reset);
+
+	return ret;
+}

Or not use goto and copy the reset_control_put() into each error path:

+static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
+{
[...]
+	ret = reset_control_assert(reset);
+	if (ret) {
+		reset_control_put(reset);
+		return dev_err_probe(dev, ret, "core_reset assert failed\n");
+	}
[...]
+	ret = reset_control_deassert(reset);
+	if (ret) {
+		reset_control_put(reset);
+		return dev_err_probe(dev, ret, "core_reset deassert failed\n");
+	}
+
+	usleep_range(200, 210);
+	reset_control_put(reset);
+
+	return 0;
+}

regards
Philipp
>