Re: [PATCH v4 0/2] [SCSI] Asynchronous event notificationinfrastructure

[James Bottomley]

On Mon, 2007-10-29 at 10:42 -0400, Jeff Garzik wrote:
> This is the next revision of the SCSI event notification infrastructure
> patchset, enabling SATA Asynchronous Notification ("AN") for CD/DVD
> devices that support it.
> 
> For devices that support SATA AN (only very recent ones do), this means
> that HAL and other userspace utilities no longer need to repeatedly poll
> the CD/DVD device to determine if the user has changed the media.
> 
> This revision takes into account James' comments from earlier today,
> modulo the following notes:
> 
> * I think the various event attributes should always be present,
>   for all devices at all times.  If various events are not supported,
>   the attribute will of course return zero (false, not supported).

Actually, I don't think so.  We have precedent for this in the transport
classes: if a device doesn't support a feature, we don't export the flag
for that feature through sysfs.  This allows not only feature control,
but an immediate view of the device capabilities simply by viewing the
sysfs directory.

I think this functionality is very easy to layer in, so there's no
reason not to do it.

> * I do not think this work should be blocked behind a revamp
>   of the attribute group interface.

Assuming gregkh or kay ack, it won't be.

> * I was slack and did not bother to implement the 'set' operation
>   for the attributes.  This can easily be done at a later time in a
>   separate patch.  It is not a merge stopper to have the driver
>   exclusively control the event mask, rather than driver+sysfs.

James


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