Major changes for hardware interrupt handling

Martin Whitlock martin.whitlock
Fri Nov 22 03:09:18 PST 2002

Well done Jouni!

I have tested this both on StrongARM and XScale pxa250 with 2.4.18 kernel.
Seems to work great! Especially on the XScale I see an increase in system
performance. The PCMCIA byte read bug in the XScale made the driver occupy
hw irq a _LONG_ time before. With the new irq handling it looks much better.



> -----Original Message-----
> From: hostap-admin at [mailto:hostap-admin at]On Behalf Of
> Jouni Malinen
> Sent: den 21 november 2002 16:31
> To: hostap at
> Subject: Major changes for hardware interrupt handling
> I just finished committing major changes to hardware interrupt handling
> in the Host AP driver. Please do note, that the new code has not been
> tested throughly, so there may well be problems with it. I have been
> using 2.5.47 kernel in my tests and thus far haven't even once compiled
> new code for 2.2.x kernels..
> The driver is now trying to get out of the hw irq context as soon as
> possible. This means that RX, info, TX, and TX Exc event processing only
> schedules a tasklet to take care of the event, masks these events from
> generating new interrupts during processing, and ACKs hw irq. Then data
> is read in tasklet (SoftIRQ) and queued in a driver queue and a new
> tasklet is scheduled to take care of rest of the processing (including
> 802.11 to Ethernet header conversion, possible host-based decryption,
> etc.). This will hopefully help with platforms that may have had
> problems with missed or delayed irqs.
> These changes remove all hardware irq context from the AP code
> (hostap_ap.c), so it can use lighter locking. In addition, I removed
> some hardware specific code from hostap_ap.c and hopefully will get rest
> of it removed at some point in the future. Most of the code in
> hostap_hw.c is now running in softirq context, so locking is lighter
> also in this file and hw irqs should not be disabled for long periods of
> time anymore.
> --
> Jouni Malinen                                            PGP id EFC895FA
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