[alsa-devel] [PATCH] asoc/multi-component: fsl: add support for variable SSI FIFO depth

Tabi Timur-B04825 B04825 at freescale.com
Thu Aug 5 17:14:55 CEST 2010

Mark Brown wrote:
>> >  The whole point behind having a device tree is to specify device
>> >  information that cannot be probed.  So every piece of information in the
>> >  DT is something that the driver needs to be told because there is no way
>> >  to query the hardware.

> This seems crazy, it means that we're not able to use new support for
> hardware features to the driver which require any kind of flag or data
> without also going through and updating the device trees for all
> existing boards.  That doesn't seem terribly helpful.

Hey, what do you want me to do?  That's just the way the hardware is 
designed.  It is not possible for software to know the FIFO depth of the SSI 
on its own, because there is no register that can be queried.  The device 
tree was designed specifically for this purpose -- the provide a data 
structure (e.g. not kernel code) that describes all of the unprobe-able 
features of the various devices on the SOC.

> I'm fairly sure that some of the previous discussion with other device
> tree people suggested that this was something that there was
> infrastructure to cope with.

I have no idea what you're talking about.

Timur Tabi
Linux kernel developer

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