Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: (EXT) Re: [PATCH mmc-next v2] mmc: allow setting slot index via device tree alias | From | Matthias Schiffer <> | Date | Tue, 25 Aug 2020 13:24:10 +0200 |
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On Tue, 2020-08-25 at 11:39 +0200, Matthias Schiffer wrote: > On Tue, 2020-08-25 at 11:14 +0200, Ulf Hansson wrote: > > On Thu, 20 Aug 2020 at 09:59, Matthias Schiffer > > <matthias.schiffer@ew.tq-group.com> wrote: > > > + > > > +static void __init mmc_of_reserve_idx(void) > > > +{ > > > + int max; > > > + > > > + max = of_alias_get_highest_id("mmc"); > > > > Is calling of_alias_get_highest_id("mmc") costly from an execution > > point of view? > > > > If not, we might as well call it directly from mmc_alloc_host() > > each > > time a host is allocated instead, to simplify the code a bit. > > It's not particularly costly (it just walks the list of aliases once > and does a string comparison for each entry), but it does so while > holding the of_mutex. > > Both variants exist in the current kernel: The I2C core stores the > hightest index in a global variable, while of_alias_get_highest_id() > is > called once for each registered SPI controller. I have a slight > preference for the global variable solution.
Looking at this again, it's pretty much the same as of_alias_get_id(). I'll remove the extra functions and global variable.
Kind regards, Matthias
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