linux-kernel - Re: [PATCH v2] net: stmmac: explicitly deassert GMAC_AHB

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Date:   Mon, 07 Jun 2021 11:45:40 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Matthew Hagan <mnhagan88@...il.com>
Cc:     bjorn.andersson@...aro.org,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        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>,
        Mohammad Athari Bin Ismail <mohammad.athari.ismail@...el.com>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: stmmac: explicitly deassert GMAC_AHB_RESET

On Sun, 2021-06-06 at 11:30 +0100, 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.
> 
> v2 changes:
>  - remove NULL condition check for stmmac_ahb_rst in stmmac_main.c
>  - unwrap dev_err() message in stmmac_main.c
>  - add PTR_ERR() around plat->stmmac_ahb_rst in stmmac_platform.c
> 
> Signed-off-by: Matthew Hagan <mnhagan88@...il.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 4 ++++
>  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
>  include/linux/stmmac.h                                | 1 +
>  3 files changed, 12 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 6d41dd6f9f7a..0d4cb423cbbd 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -6840,6 +6840,10 @@ int stmmac_dvr_probe(struct device *device,
>  			reset_control_reset(priv->plat->stmmac_rst);
>  	}
>  
> +	ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
> +	if (ret == -ENOTSUPP)
> +		dev_err(priv->device, "unable to bring out of ahb reset\n");
> +

I would make this

	if (ret)
		dev_err(priv->device, "unable to bring out of ahb reset: %pe\n", ERR_PTR(ret));

Also consider asserting the reset again in the remove path. Or is there
a reason not to?

With that addressed,

Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>

regards
Philipp