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Subject: Re: [PATCH net v2 1/1] net: ravb: Wait for operation mode to be
 applied
To: Claudiu <claudiu.beznea@tuxon.dev>, <davem@davemloft.net>,
	<edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
	<yoshihiro.shimoda.uh@renesas.com>, <wsa+renesas@sang-engineering.com>,
	<mitsuhiro.kimura.kc@renesas.com>
CC: <netdev@vger.kernel.org>, <linux-renesas-soc@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, Claudiu Beznea
	<claudiu.beznea.uj@bp.renesas.com>
References: <20231222113552.2049088-1-claudiu.beznea.uj@bp.renesas.com>
 <20231222113552.2049088-2-claudiu.beznea.uj@bp.renesas.com>
From: Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <98efc508-c431-2509-5799-96decc124136@omp.ru>
Date: Sat, 23 Dec 2023 22:39:50 +0300
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On 12/22/23 2:35 PM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> 
> CSR.OPS bits specify the current operating mode and (according to
> documentation) they are updated by HW when the operating mode change
> request is processed. To comply with this check CSR.OPS before proceeding.
> 
> Commit introduces ravb_set_opmode() that does all the necessities for
> setting the operating mode (set DMA.CCC and wait for CSR.OPS) and call it
> where needed. This should comply with all the HW manuals requirements as
> different manual variants specify that different modes need to be checked
> in CSR.OPS when setting DMA.CCC.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 52 ++++++++++++++----------
>  1 file changed, 31 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 664eda4b5a11..ae99d035a3b6 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -66,14 +66,15 @@ int ravb_wait(struct net_device *ndev, enum ravb_reg reg, u32 mask, u32 value)
>  	return -ETIMEDOUT;
>  }
>  
> -static int ravb_config(struct net_device *ndev)
> +static int ravb_set_opmode(struct net_device *ndev, u32 opmode)

   Since you pass the complete CCC register value below, you should
rather call the function ravb_set_ccc() and call the parameter opmode
ccc.

>  {
> +	u32 csr_opmode = 1UL << opmode;

   Please use the correct expression, 1U << (ccc & CCC_OPC) instead.
And I'd suggest calling the variable csr_ops or just ops.

>  	int error;
>  
> -	/* Set config mode */
> -	ravb_modify(ndev, CCC, CCC_OPC, CCC_OPC_CONFIG);
> -	/* Check if the operating mode is changed to the config mode */
> -	error = ravb_wait(ndev, CSR, CSR_OPS, CSR_OPS_CONFIG);
> +	/* Set operating mode */
> +	ravb_modify(ndev, CCC, CCC_OPC, opmode);
> +	/* Check if the operating mode is changed to the requested one */
> +	error = ravb_wait(ndev, CSR, CSR_OPS, csr_opmode);
>  	if (error)
>  		netdev_err(ndev, "failed to switch device to config mode\n");

   s/config/requested/? Or just print out that mode...

[...]
> @@ -2560,21 +2559,23 @@ static int ravb_set_gti(struct net_device *ndev)
>  	return 0;
>  }
>  
> -static void ravb_set_config_mode(struct net_device *ndev)
> +static int ravb_set_config_mode(struct net_device *ndev)
>  {
>  	struct ravb_private *priv = netdev_priv(ndev);
>  	const struct ravb_hw_info *info = priv->info;
> +	int error;
>  
>  	if (info->gptp) {
> -		ravb_modify(ndev, CCC, CCC_OPC, CCC_OPC_CONFIG);
> +		error = ravb_set_opmode(ndev, CCC_OPC_CONFIG);

   Don't we need to return on error here?

>  		/* Set CSEL value */
>  		ravb_modify(ndev, CCC, CCC_CSEL, CCC_CSEL_HPB);
>  	} else if (info->ccc_gac) {
> -		ravb_modify(ndev, CCC, CCC_OPC, CCC_OPC_CONFIG |
> -			    CCC_GAC | CCC_CSEL_HPB);
> +		error = ravb_set_opmode(ndev, CCC_OPC_CONFIG | CCC_GAC | CCC_CSEL_HPB);

   See, you pass more than just CCC.OPC value here -- need to mask it out
above...

[...]
> @@ -2917,8 +2921,9 @@ static void ravb_remove(struct platform_device *pdev)
>  	dma_free_coherent(ndev->dev.parent, priv->desc_bat_size, priv->desc_bat,
>  			  priv->desc_bat_dma);
>  
> -	/* Set reset mode */
> -	ravb_write(ndev, CCC_OPC_RESET, CCC);
> +	error = ravb_set_opmode(ndev, CCC_OPC_RESET);
> +	if (error)
> +		netdev_err(ndev, "Failed to reset ndev\n");

   ravb_set_opmode() will have complained already at this point...

[...]

MBR, Sergey