On 1/25/2011 5:36 AM, Mark Brown wrote:
On Mon, Jan 24, 2011 at 10:13:33PM -0800, Patrick Lai wrote:
What we're doing for this currently is passing the configuration data in
platform data or via request_firmware() (mostly using the latter for
larger data). At the minute we're loading everything at startup rather
than on demand, with the drivers presenting an enum with the available
use cases if there's more than one.
Can you point me to an example driver which does exactly what you
describe? Loading at startup is what I would like to avoid. That means
calibration data for all use cases would be packed into single binary file.
perform extensive parsing of data. Furthermore, host processor and
co-processor need to establish common use case definitions so
co-processor know what chunk of calibration data to apply in certain
scenario such as device switch.
I don't understand the issue with either parsing cost or with listing
use cases - I'd expect that for multiple use cases the host processor
and (if required) the coprocessor would parse the set of use cases out
of the data (for many systems the coprocessor won't know anything about
use cases and they'll be managed by the host reprogramming coefficients
to switch), and I'd expect that either the format will be defined to
something readily usable or the host can do the required processing.
Could you elaborate on the issues here, it's possible I'm missing
something about the sort of data you're looking at?
Parsing is not a big concern as the co-processor in question does
parsing to some extend. The calibration binary contains coefficients for
different features on the co-processor for a given playback or capture
path. I would like to keep parsing based on features(i.e type of filter)
supported on the co-processor but stay use case agnostic. A more
concrete example would be reapplying calibration data for different
device mode(speaker, headphone). In this case, if calibrations data for
all devices is packed into single binary, host-processor and
co-processor would need to maintain common device ID. When there is
device switch, host-processor passes new device ID so co-processor know
the right set of calibration to apply. As a device mode is constructed
by connecting components in the CODEC through mixer commands,
co-processor should also stay device-mode agnostic. That's why I believe
push down model would work better based what I have stated above.
If there is no precedent, my idea is to apply calibration data
through sysfs. After introduction of ASoC multi-component
architecture, PCM stream created from dailink is registered as
device. So, there is syfs entry for each dailink. If ALSA ASoC can
provide API for drivers(platform/CPU) to register additional
attributes to the PCM device, this approach gives user-space
application the ability to push down new calibration as audio
situation changes. I believe it's a viable solution to my problem
and perhaps can be useful to other systems as well.
I'm not enthused about sysfs for this as it means applications end up
needing custom infrastructure for individual cards, or UCM needs to end
up integrating that anyway, so we'd have some issues at the application
level when writing generic code for multiple systems
That's exactly why we need UCM, right? Though application request for
headphone device, different system would have different set of mixer
controls to construct headphone device. That's why I do not see why each
DAI link cannot have its own unique attributes.
we'd need support
for enumerating and understanding the available settings. In terms of
actually loading the data it doesn't really offer anything that
request_firmware() doesn't except for a push interface and it's not got
the existing userspace infrastructure that request_firmware() does.
Request_frmware() can accomplish my request but requires common device
ID to be defined. If there is new use case with new device defined,
co-processor would have to be updated with new ID and it's not a
scalable solution. Another approach is to devise mixer command which
passes name of calibration file. This command triggers
request_firmware() being called with file name passed as parameter of
the command. The caveat is, unless user-space application wants to
extract calibration data for a device mode and save into file system at
run-time, we would end up having numerous calibration files in the file
system.
Thinking off the top of my head I think we're reasonably covered from
the point of view of actually injecting data already but we currently
don't have a way to add additional data at runtime (eg, when doing a
calibration run). If we added a way for applications to say "I'd like
to add some new coefficients to this feature" then that would address
that aspect of things, I think?
--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
