Messages in this thread | | | Date | Mon, 7 Feb 2011 09:24:58 -0500 (EST) | From | Nicolas Pitre <> | Subject | Re: [RFC, PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics |
| |
On Mon, 7 Feb 2011, Jeremy Kerr wrote:
> Hi Uwe, > > > This implies the warning is only issued on clocks that have a prepare > > callback. If we want to enforce the new API the warning here shouldn't > > depend on clk->ops->prepare. (clk_prepare and clk_unprepare need to > > be changed then to adapt the prepare_count even in the absence of > > clk->ops->prepare.) > > Yeah, it's a decision about either adding a small cost to all clk_prepare()s > (ie, adding cost when there is no prepare callback), or checking for the > correct prepare/enable semantics for all clocks (even when it doesn't matter > for that particular clock). I chose the first as more important, but happy to > go either way here.
The prepare method being called from non-atomic context cannot be considered to be in a speed critical path. Most of the time, this is going to be called on driver initialization or the like, and that's a relatively rare event. Therefore this really small cost to clk_prepare() is definitively worth it to help proper usage of the API. If this ever becomes a problem then this could be confined to some CONFIG_CLK_DEBUG or the like. But when introducing a new API it is best to be more strict to help people get its usage right (without going overboard with it of course).
Nicolas
| |