On 06/09/2016 06:24 PM, Mauro Carvalho Chehab wrote:
Hi Akihiro,
Em Thu, 09 Jun 2016 21:49:33 +0900
Akihiro TSUKADA <tskd08@xxxxxxxxx> escreveu:
Hi,
excuse me for taking up a very old post again,
but I'd like to know the status of the patch:
https://patchwork.linuxtv.org/patch/27922/
, which provides helper code for defining/loading i2c DVB subdev drivers.
Was it rejected and
It was not rejected. It is just that I didn't have time yet to think
about that, and Antti has a different view.
The thing is that, whatever we do, it should work fine on drivers that
also exposes the tuner via V4L2. One of the reasons is that devices
that also allow the usage for SDR use the V4L2 core for the SDR part.
each i2c demod/tuner drivers should provide its own version of "attach" code?
Antti took this path, but I don't like it. Lots of duplicated and complex
stuff. Also, some static analyzers refuse to check it (like smatch),
due to its complexity.
Or is it acceptable (with some modifications) ?
I guess we should discuss a way of doing it that will be acceptable
on existing drivers. Perhaps you should try to do such change for
an hybrid driver like em28xx or cx231xx. There are a few ISDB-T
devices using them. Not sure how easy would be to find one of those
in Japan, though.
Although not many drivers currently use i2c binding model (and use dvb_attach()),
but I expect that coming DVB subdev drivers will have a similar attach code,
including module request/ref-counting, device creation,
(re-)using i2c_board_info.platformdata to pass around both config parameters
and the resulting i2c_client* & dvb_frontend*.
Since I have a plan to split out demod/tuner drivers from pci/pt1 dvb-usb/friio
integrated drivers (because those share the tc90522 demod driver with pt3, and
friio also shares the bridge chip with gl861),
it would be nice if I can use the helper code,
instead of re-iterating similar "attach" code.
IMHO only thing which makes it looking complex is that module reference
counting - otherwise it is just standard I2C binding. Ideally I2C
modules should be possible to unbind and unload at runtime and also load
and bind. There is "suppress_bind_attrs = true" set to prevent runtime
unbinding and try_module_get() is to prevent module unloading. For me
eyes all that is still some workaround - and now you want put this
workaround to some generic code. Please find correct solutions for those
two problems and then there we can get rid of things totally - no need
to make generic functions at all.
regards
Antti
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