Re: [PATCH] New: Omnikey CardMan 4040 PCMCIA Driver

[Harald Welte]

On Sat, Sep 03, 2005 at 04:27:00PM -0500, Chase Venters wrote:
> > Below you can find a driver for the Omnikey CardMan 4040 PCMCIA
> > Smartcard Reader.
> 
> Someone correct me if I'm wrong, but wouldn't these #defines be a problem with 
> the new HZ flexibility:
> 
> #define	CCID_DRIVER_BULK_DEFAULT_TIMEOUT  	(150*HZ)
> #define	CCID_DRIVER_ASYNC_POWERUP_TIMEOUT 	(35*HZ)
> #define	CCID_DRIVER_MINIMUM_TIMEOUT 		(3*HZ)

The defines above certainly have no problems.  They want to wait for
multiples of seconds.

> /* how often to poll for fifo status change */
> #define POLL_PERIOD 				(HZ/100)
> 
> In particular, 2.6.13 allows a HZ of 100, which would define POLL_PERIOD to 0. 
> Your later calls to mod_timer would be setting cmx_poll_timer to the current 
> value of jiffies. 

100/100 == 1.  As far as my limited math skills go, only 0 divided by
something can give a result of zero ;)

So yes, the code would poll every 1/100th of a second, even with HZ=100.  

Obviously, if HZ would ever go below 100, the code above would provide
some problems.  I'm not sure what the future plans with HZ are, but I'll
add an #error statement in case HZ goes smaller than that.

> Also, you've got a typo in the comments:

thanks.

-- 
- Harald Welte <laforge@xxxxxxxxxxxx>          	        http://gnumonks.org/
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