netdev - Re: [PATCH] macb: propagate errors when getting optional clocks

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Date:   Fri, 18 Oct 2019 15:53:36 +0000
From:   <Nicolas.Ferre@...rochip.com>
To:     <m.tretter@...gutronix.de>, <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <alexandre.belloni@...tlin.com>,
        <antoine.tenart@...tlin.com>, <Claudiu.Beznea@...rochip.com>
Subject: Re: [PATCH] macb: propagate errors when getting optional clocks

On 18/10/2019 at 16:11, Michael Tretter wrote:
> The tx_clk, rx_clk, and tsu_clk are optional. Currently the macb driver
> marks clock as not available if it receives an error when trying to get
> a clock. This is wrong, because a clock controller might return
> -EPROBE_DEFER if a clock is not available, but will eventually become
> available.
> 
> In these cases, the driver would probe successfully but will never be
> able to adjust the clocks, because the clocks were not available during
> probe, but became available later.
> 
> For example, the clock controller for the ZynqMP is implemented in the
> PMU firmware and the clocks are only available after the firmware driver
> has been probed.
> 
> Use devm_clk_get_optional() in instead of devm_clk_get() to get the
> optional clock and propagate all errors to the calling function.
> 
> Signed-off-by: Michael Tretter <m.tretter@...gutronix.de>

Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Tested-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
(for the record: on sama5d3 xplained GMAC and MACB interfaces)

Thank you Michael. Best regards,
   Nicolas

> ---
>   drivers/net/ethernet/cadence/macb_main.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 8e8d557901a9..1e1b774e1953 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -3405,17 +3405,17 @@ static int macb_clk_init(struct platform_device *pdev, struct clk **pclk,
>   		return err;
>   	}
>   
> -	*tx_clk = devm_clk_get(&pdev->dev, "tx_clk");
> +	*tx_clk = devm_clk_get_optional(&pdev->dev, "tx_clk");
>   	if (IS_ERR(*tx_clk))
> -		*tx_clk = NULL;
> +		return PTR_ERR(*tx_clk);
>   
> -	*rx_clk = devm_clk_get(&pdev->dev, "rx_clk");
> +	*rx_clk = devm_clk_get_optional(&pdev->dev, "rx_clk");
>   	if (IS_ERR(*rx_clk))
> -		*rx_clk = NULL;
> +		return PTR_ERR(*rx_clk);
>   
> -	*tsu_clk = devm_clk_get(&pdev->dev, "tsu_clk");
> +	*tsu_clk = devm_clk_get_optional(&pdev->dev, "tsu_clk");
>   	if (IS_ERR(*tsu_clk))
> -		*tsu_clk = NULL;
> +		return PTR_ERR(*tsu_clk);
>   
>   	err = clk_prepare_enable(*pclk);
>   	if (err) {
> 


-- 
Nicolas Ferre