This ensures consistent handling of the SR_CONF_SCAN_OPTIONS and
SR_CONF_DEVICE_OPTIONS (with sdi NULL or non-NULL) config keys
and also reduces copy-pasted boilerplate in the drivers a bit.
This function does not handle channel-group specific items, that's
very driver-specific and thus left to the individual drivers.
Also move some generic checks and error messages from the drivers into
the sr_config_list() wrapper.
Until now, clear_helper() callbacks for std_dev_clear_with_callback()
were expected to g_free(devc), but not all of them did that.
Have std_dev_clear_with_callback() unconditionally g_free(sdi->priv)
(i.e., devc), regardless of whether a clear_helper() callback was
provided or not. It was doing g_free(sdi->priv) when no callback
was provided already anyway.
This makes the individual drivers' clear_helper() implementations
shorter and prevents errors such as missing g_free(devc) calls.
This works, because all drivers either call std_dev_clear_with_callback()
directly, or indirectly via std_dev_clear().
This also allows us to remove some no-longer needed dev_clear()
and clear_helper() implementations that only did g_free(devc)
in favor of std_dev_clear().
Before firmware upload some models (e.g. the original DSLogic or the
DSLogic Pro) don't have any USB manufacturer or product strings set, so
they wouldn't be detected.
Uwe Hermann