Re: [RESEND PATCH 05/14] eeprom: at24: hide the read/write loop behind a macro

From: Wolfram Sang
Date: Fri Jul 15 2016 - 08:24:52 EST


> +/*
> + * Both reads and writes fail if the previous write didn't complete yet. This
> + * macro loops a few times waiting at least long enough for one entire page
> + * write to work.
> + *
> + * It takes two parameters: a variable in which the future timeout in jiffies
> + * will be stored and a temporary variable holding the time of the last
> + * iteration of processing the request. Both should be unsigned integers
> + * holding at least 32 bits.
> + */
> +#define loop_until_timeout(tout, op_time) \
> + for (tout = jiffies + msecs_to_jiffies(write_timeout), \
> + op_time = jiffies; \
> + time_before(op_time, tout); \
> + usleep_range(1000, 1500), op_time = jiffies)

There is one subtle change coming with this change: the do-while loop is
guaranteed to run at least once while the for-loop doesn't.

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