linux-kernel - Re: [PATCH 1/3] net: stmmac: explicitly deassert GMAC_AHB

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Date:   Sun, 6 Jun 2021 10:36:33 +0100
From:   Matthew Hagan <mnhagan88@...il.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Voon Weifeng <weifeng.voon@...el.com>,
        Ong Boon Leong <boon.leong.ong@...el.com>,
        Wong Vee Khee <vee.khee.wong@...ux.intel.com>,
        Tan Tee Min <tee.min.tan@...el.com>,
        "Wong, Vee Khee" <vee.khee.wong@...el.com>,
        Fugang Duan <fugang.duan@....com>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] net: stmmac: explicitly deassert GMAC_AHB_RESET

On 06/06/2021 04:24, Bjorn Andersson wrote:

> On Sat 05 Jun 12:35 CDT 2021, Matthew Hagan wrote:
>
>> We are currently assuming that GMAC_AHB_RESET will already be deasserted
>> by the bootloader. However if this has not been done, probing of the GMAC
>> will fail. To remedy this we must ensure GMAC_AHB_RESET has been deasserted
>> prior to probing.
>>
> Sounds good, just some small style comments below.
>
>> Signed-off-by: Matthew Hagan <mnhagan88@...il.com>
>> ---
>>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 7 +++++++
>>  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
>>  include/linux/stmmac.h                                | 1 +
>>  3 files changed, 15 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> index 6d41dd6f9f7a..1e28058b65a8 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
>> @@ -6840,6 +6840,13 @@ int stmmac_dvr_probe(struct device *device,
>>  			reset_control_reset(priv->plat->stmmac_rst);
>>  	}
>>  
>> +	if (priv->plat->stmmac_ahb_rst) {
> You don't need this conditional, stmmac_ahb_rst will be NULL if not
> specified and you can reset_control_deassert(NULL) without any problems.
>
>> +		ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
>> +		if (ret == -ENOTSUPP)
>> +			dev_err(priv->device,
>> +				"unable to bring out of ahb reset\n");
> No need to wrap this line.
>
>> +	}
>> +
>>  	/* Init MAC and get the capabilities */
>>  	ret = stmmac_hw_init(priv);
>>  	if (ret)
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>> index 97a1fedcc9ac..d8ae58bdbbe3 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>> @@ -600,6 +600,13 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
>>  		goto error_hw_init;
>>  	}
>>  
>> +	plat->stmmac_ahb_rst = devm_reset_control_get_optional_shared(
>> +							&pdev->dev, "ahb");
>> +	if (IS_ERR(plat->stmmac_ahb_rst)) {
>> +		ret = plat->stmmac_ahb_rst;
> You need a PTR_ERR() around the plat->stmmac_ahb_rst.
>
> Regards,
> Bjorn
>
>> +		goto error_hw_init;
>> +	}
>> +
>>  	return plat;
>>  
>>  error_hw_init:
>> diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
>> index e55a4807e3ea..9b6a64f3e3dc 100644
>> --- a/include/linux/stmmac.h
>> +++ b/include/linux/stmmac.h
>> @@ -239,6 +239,7 @@ struct plat_stmmacenet_data {
>>  	unsigned int mult_fact_100ns;
>>  	s32 ptp_max_adj;
>>  	struct reset_control *stmmac_rst;
>> +	struct reset_control *stmmac_ahb_rst;
>>  	struct stmmac_axi *axi;
>>  	int has_gmac4;
>>  	bool has_sun8i;
>> -- 
>> 2.26.3
>>
>>
Thanks for the review. Will submit a v2 shortly.

Matthew