netdev - Re: [PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on wait user access

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Message-ID: <d176da18-b608-9738-317c-6ca01cb937e9@ti.com>
Date:   Thu, 10 Aug 2017 11:24:50 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Max Uvarov <muvarov@...il.com>, <netdev@...r.kernel.org>
CC:     <linux-omap@...r.kernel.org>
Subject: Re: [PATCHv2 1/2] drivers: net: davinci_mdio: remove busy loop on
 wait user access



On 08/10/2017 02:47 AM, Max Uvarov wrote:
> Polling 14 mdio devices on single mdio bus eats 30% of 1Ghz cpu time
> due to busy loop in wait(). Add small delay to relax cpu.
> 
> Signed-off-by: Max Uvarov <muvarov@...il.com>

yep. cover letter is good to have.

Reviewed-by: Grygorii Strashko <grygorii.strashko@...com>

> ---
>   v2: fix spelling in commit description.
> 
>   drivers/net/ethernet/ti/davinci_mdio.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/ti/davinci_mdio.c b/drivers/net/ethernet/ti/davinci_mdio.c
> index 33df340..611e7cc 100644
> --- a/drivers/net/ethernet/ti/davinci_mdio.c
> +++ b/drivers/net/ethernet/ti/davinci_mdio.c
> @@ -198,8 +198,10 @@ static inline int wait_for_user_access(struct davinci_mdio_data *data)
>   			return 0;
>   
>   		reg = __raw_readl(&regs->control);
> -		if ((reg & CONTROL_IDLE) == 0)
> +		if ((reg & CONTROL_IDLE) == 0) {
> +			usleep_range(100, 200);
>   			continue;
> +		}
>   
>   		/*
>   		 * An emac soft_reset may have clobbered the mdio controller's
> 

-- 
regards,
-grygorii