Messages in this thread | | | Date | Fri, 12 Feb 2016 11:33:17 -0700 | Subject | Re: [PATCH V3 1/6] stm class: Add ioctl get_options interface | From | Mathieu Poirier <> |
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On 12 February 2016 at 08:18, Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote: > Chunyan Zhang <zhang.chunyan@linaro.org> writes: > >> There is already an interface of set_options, but no get_options yet. >> Before setting any options, one would may want to see the current >> status of that option by means of get_options interface. This >> interface has been used in CoreSight STM driver. > > I'm not sure I understand the reasoning behind this. If a userspace > program opens a communication channel and wants to configure certain > features on it, why does its choice depend on what has been configured > for this channel previously? It can be anything at all. Most likely, > it's either unconfigured or configured to its default values, but why > does this matter for a new writer?
A client may wish to change the settings (invariant/guaranteed) it has on a specific channel - it may even want to so do multiple times. The idea behind introducing a get_options() was to probe the specific settings of a channel before going a head with a new configuration. In hindsight it may not be needed as a client should simply go ahead and push down the configuration it wants.
> > Regards, > -- > Alex
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