On Tue, 25 Jan 2011, Ryan Mallon wrote: > On 01/25/2011 09:28 AM, Julia Lawall wrote: > >> Julia is correct. Some architectures can return NULL from clk_get, but I > >> didn't check the at91 before posting :-/. If we can't return NULL from > >> clk_get then we shouldn't bother checking for it. I do think we should > >> drop the !IS_ERR(clk_get(dev, func)) check though. > > > > It seems a bit subtle, because the clk manipulated by clk_get in the call > > of clk_get(dev, func) is not necessarily the same as the one in > > clock_associate. But perhaps this is the only possibility in practice? > > Not sure I follow. The at91 clk_get does not modify the clk. In > at91_clock_associate we have: > > clk->function = func; > clk->dev = dev; > > and in clk_get we have: > > if (clk->function && (dev == clk->dev) && > strcmp(id, clk->function) == 0) > return clk; > > So at91_clock_associate sets the function for a clock, and clk_get > returns clocks based on the function association if the name lookup > fails. The only caveat to this is that the the clock function name > (clk->function) is not the same as any others clock's clk->name. Right, that was what I was worried about. That one would find the same information already present but somewhere else. But perhaps it can't happen, or it doesn't matter if it does? julia > The !IS_ERR(clk_get(dev, func)) check in at91_clock_associate just > appears to check that the clock is not already associated with the given > function. We don't really need this check because we are just making the > same assignment anyway. > > ~Ryan > > -- > Bluewater Systems Ltd - ARM Technology Solution Centre > > Ryan Mallon 5 Amuri Park, 404 Barbadoes St > ryan@xxxxxxxxxxxxxxxx PO Box 13 889, Christchurch 8013 > http://www.bluewatersys.com New Zealand > Phone: +64 3 3779127 Freecall: Australia 1800 148 751 > Fax: +64 3 3779135 USA 1800 261 2934 > -- > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
