On 19 June 2014 16:23, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > On 06/19/2014 04:03 PM, Hans de Goede wrote: >> Hi, >> > > <snip> > >> Also I'm not sold on how you're making this a devm only thing, and >> are using devres_alloc to not only allocate memory for resource tracking, >> but also the actual backing struct, that is not how devres_alloc is >> intended to be used AFAIK. >> >> A problem with having this one always devm managed is that it makes it >> hard to use in library functions without side effects. >> >> e.g. if you look at how your using this in mmc_of_parse in the next >> patch, this gives mmc_of_parse the side-effect of having allocated >> and bound the power-seq method, even if mmc_of_parse later >> fails on e.g. gpio binding. If then for some reason the mmc host >> probe method decides to not propagate the mmc_of_parse method >> error (leading to freeing of all devm managed resources), then this is >> undesirable. >> >> Where as with a non devm version, it would be clear that on error >> mmc_of_parse would need to explicitly release the pwrseq again. >> >> I realize that pwrseq implementations likely will want to use >> devm functions too, and I'm a great fan of devm. But this is something >> to keep in mind. At a minimum the description of of_mmc_parse needs >> to get updated with info about it having potential side-effects even >> when it fails, and that failure should always be treated as a fatal >> error and cause the host probe method to fail. > > Thinking more about this, it may be a good idea to give the pwrseq > its own struct device, turning it into a virtual device, this way the > pwrseq-method can use devm managed resources bound to this device, > we can set the of_node of this device to the actual powerseq > childnode and it gets its own sysfs dir in which we could do useful things > such as have an attribute to query the current power state. > > This would also mean introducing a non devm version of devm_pwrseq_get > + an explicit release, which would be useful to avoid the side-effects > mentioned above when used in library functions such as mmc_of_parse. Hans, thanks for your comments. I will try to include all your ideas in a v2. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
