netdev - Re: [PATCH net 2/2] net: ravb: Check that GTI loading request is done

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Date: Thu, 14 Dec 2023 23:22:15 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Claudiu <claudiu.beznea@...on.dev>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<claudiu.beznea.uj@...renesas.com>, <yoshihiro.shimoda.uh@...esas.com>,
	<wsa+renesas@...g-engineering.com>, <niklas.soderlund+renesas@...natech.se>,
	<biju.das.jz@...renesas.com>, <prabhakar.mahadev-lad.rj@...renesas.com>,
	<mitsuhiro.kimura.kc@...esas.com>, <geert+renesas@...der.be>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net 2/2] net: ravb: Check that GTI loading request is done

On 12/14/23 2:31 PM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> Hardware manual specifies the following for GCCR.LTI bit:
> 0: Setting completed
> 1: When written: Issue a configuration request.
> When read: Completion of settings is pending
> 
> Thus, check the completion status when setting 1 to GCCR.LTI.

   But do we really need to? Seems quite dubious... currently we
just let it the loading complete asynchronously...

> Fixes: 7e09a052dc4e ("ravb: Exclude gPTP feature support for RZ/G2L")
> Fixes: 568b3ce7a8ef ("ravb: factor out register bit twiddling code")
> Fixes: 0184165b2f42 ("ravb: add sleep PM suspend/resume support")
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index ce95eb5af354..1c253403a297 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2819,6 +2819,10 @@ static int ravb_probe(struct platform_device *pdev)
>  
>  		/* Request GTI loading */
>  		ravb_modify(ndev, GCCR, GCCR_LTI, GCCR_LTI);
> +		/* Check completion status. */
> +		error = ravb_wait(ndev, GCCR, GCCR_LTI, 0);
> +		if (error)
> +			goto out_disable_refclk;
>  	}
>  
>  	if (info->internal_delay) {
> @@ -3041,6 +3045,10 @@ static int __maybe_unused ravb_resume(struct device *dev)
>  
>  		/* Request GTI loading */
>  		ravb_modify(ndev, GCCR, GCCR_LTI, GCCR_LTI);
> +		/* Check completion status. */
> +		ret = ravb_wait(ndev, GCCR, GCCR_LTI, 0);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	if (info->internal_delay)
> 

   BTW, seems worth factoring out into a separate function...

MBR, Sergey