netdev - Re: [PATCH v3 4/5] ravb: Use separate clock for gPTP

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Date:   Thu, 12 May 2022 09:02:32 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Phil Edworthy <phil.edworthy@...esas.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        Biju Das <biju.das.jz@...renesas.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v3 4/5] ravb: Use separate clock for gPTP

On Tue, 2022-05-10 at 10:03 +0100, Phil Edworthy wrote:
> RZ/V2M has a separate gPTP reference clock that is used when the
> AVB-DMAC Mode Register (CCC) gPTP Clock Select (CSEL) bits are
> set to "01: High-speed peripheral bus clock".
> Therefore, add a feature that allows this clock to be used for
> gPTP.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@...esas.com>
> Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
> ---
> v3:
>  - No change
> v2:
>  - Added Reviewed-by tags
> ---
>  drivers/net/ethernet/renesas/ravb.h      |  2 ++
>  drivers/net/ethernet/renesas/ravb_main.c | 15 ++++++++++++++-
>  2 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> index e505e8088445..b980bce763d3 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -1031,6 +1031,7 @@ struct ravb_hw_info {
>  	unsigned err_mgmt_irqs:1;	/* Line1 (Err) and Line2 (Mgmt) irqs are separate */
>  	unsigned gptp:1;		/* AVB-DMAC has gPTP support */
>  	unsigned ccc_gac:1;		/* AVB-DMAC has gPTP support active in config mode */
> +	unsigned gptp_ref_clk:1;	/* gPTP has separate reference clock */
>  	unsigned nc_queues:1;		/* AVB-DMAC has RX and TX NC queues */
>  	unsigned magic_pkt:1;		/* E-MAC supports magic packet detection */
>  	unsigned half_duplex:1;		/* E-MAC supports half duplex mode */
> @@ -1042,6 +1043,7 @@ struct ravb_private {
>  	void __iomem *addr;
>  	struct clk *clk;
>  	struct clk *refclk;
> +	struct clk *gptp_clk;
>  	struct mdiobb_ctrl mdiobb;
>  	u32 num_rx_ring[NUM_RX_QUEUE];
>  	u32 num_tx_ring[NUM_TX_QUEUE];
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 8ccc817b8b5d..ef6967731263 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -2495,11 +2495,15 @@ MODULE_DEVICE_TABLE(of, ravb_match_table);
>  static int ravb_set_gti(struct net_device *ndev)
>  {
>  	struct ravb_private *priv = netdev_priv(ndev);
> +	const struct ravb_hw_info *info = priv->info;
>  	struct device *dev = ndev->dev.parent;
>  	unsigned long rate;
>  	uint64_t inc;
>  
> -	rate = clk_get_rate(priv->clk);
> +	if (info->gptp_ref_clk)
> +		rate = clk_get_rate(priv->gptp_clk);
> +	else
> +		rate = clk_get_rate(priv->clk);
>  	if (!rate)
>  		return -EINVAL;
>  
> @@ -2721,6 +2725,15 @@ static int ravb_probe(struct platform_device *pdev)
>  	}
>  	clk_prepare_enable(priv->refclk);
>  
> +	if (info->gptp_ref_clk) {
> +		priv->gptp_clk = devm_clk_get(&pdev->dev, "gptp");
> +		if (IS_ERR(priv->gptp_clk)) {
> +			error = PTR_ERR(priv->gptp_clk);
> +			goto out_release;
> +		}
> +		clk_prepare_enable(priv->gptp_clk);
> +	}
> +

I guess you need to a conditional

	clk_disable_unprepare(info->gptp_ref_clk)

in the error path? And even in ravb_remove()?

>  	ndev->max_mtu = info->rx_max_buf_size - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
>  	ndev->min_mtu = ETH_MIN_MTU;
>