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Date:   Tue, 31 Oct 2023 13:32:13 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc:     Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: stmmac: Wait a bit for the reset to take effect
Message-ID: <j37ktiug7vwbb7h7s44zmng5a2bjzbd663p7pfowbehapjv3by@vrxfmapscaln>
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On Mon, Oct 30, 2023 at 07:01:11AM +0100, Bernd Edlinger wrote:
> otherwise the synopsys_id value may be read out wrong,
> because the GMAC_VERSION register might still be in reset
> state, for at least 1 us after the reset is de-asserted.

From what have you got that delay value?

-Serge(y)

> 
> Add a wait for 10 us before continuing to be on the safe side.
> 
> Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 5801f4d50f95..e485f4db3605 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -7398,6 +7398,9 @@ int stmmac_dvr_probe(struct device *device,
>  		dev_err(priv->device, "unable to bring out of ahb reset: %pe\n",
>  			ERR_PTR(ret));
>  
> +	/* Wait a bit for the reset to take effect */
> +	udelay(10);
> +
>  	/* Init MAC and get the capabilities */
>  	ret = stmmac_hw_init(priv);
>  	if (ret)
> -- 
> 2.39.2
> 
>