linux-kernel - Re: [PATCH net-next 4/4] net: phy: mscc-miim: read poll when high resolution timers are disabled

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Date:   Tue, 26 May 2020 15:05:34 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Antoine Tenart <antoine.tenart@...tlin.com>, davem@...emloft.net,
        hkallweit1@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, alexandre.belloni@...tlin.com,
        thomas.petazzoni@...tlin.com, allan.nielsen@...rochip.com
Subject: Re: [PATCH net-next 4/4] net: phy: mscc-miim: read poll when high
 resolution timers are disabled



On 5/26/2020 3:01 PM, Andrew Lunn wrote:
>>> +/* When high resolution timers aren't built-in: we can't use usleep_range() as
>>> + * we would sleep way too long. Use udelay() instead.
>>> + */
>>> +#define mscc_readl_poll_timeout(addr, val, cond, delay_us, timeout_us)	\
>>> +({									\
>>> +	if (!IS_ENABLED(CONFIG_HIGH_RES_TIMERS))			\
>>> +		readl_poll_timeout_atomic(addr, val, cond, delay_us,	\
>>> +					  timeout_us);			\
>>> +	readl_poll_timeout(addr, val, cond, delay_us, timeout_us);	\
>>> +})
>>> +
>>
>> I would make this a regular function which would not harm the compiler's
>> ability to optimize it, but would give you type checking. With that fixed:
> 
> Hi Florian
> 
> cond makes that difficult, since it is not a parameter in the usual
> sense, but an expression to evaluate if the polling should terminate.
> 
> readl_poll_timeout() and readl_poll_timeout_atomic() themselves are
> #define's, and there are more levels of macros under them.

Oh that's right, thanks for reminding me of this.
-- 
Florian