> -----Original Message----- > From: Arnd Bergmann [mailto:arnd@xxxxxxxx] > Sent: Tuesday, September 02, 2014 1:45 PM > To: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Cc: Lee Jones; kgene.kim@xxxxxxxxxxx; linux@xxxxxxxxxxxxxxxx; > naushad@xxxxxxxxxxx; Pankaj Dubey; Tomasz Figa; linux-kernel@xxxxxxxxxxxxxxx; > joshi@xxxxxxxxxxx; vikas.sajjan@xxxxxxxxxxx; linux-samsung- > soc@xxxxxxxxxxxxxxx; broonie@xxxxxxxxxx; thomas.ab@xxxxxxxxxxx; > chow.kim@xxxxxxxxxxx > Subject: Re: [PATCH] mfd: syscon: Decouple syscon interface from syscon devices > > On Tuesday 02 September 2014 09:05:16 Lee Jones wrote: > > On Mon, 01 Sep 2014, Arnd Bergmann wrote: > > > > > On Monday 01 September 2014 17:04:26 Lee Jones wrote: > > > > On Mon, 01 Sep 2014, Arnd Bergmann wrote: > > > > > Maybe I'm misreading the patch, but I don't see how it creates a > > > > > migration path. What I want to end up with is infrastructure > > > > > that lets anybody call syscon_regmap_lookup_by_pdevname or > > > > > syscon_regmap_lookup_by_compatible (if they really need to) > > > > > without needing the platform_driver for syscon. That should not > > > > > require any form of compatibility layer because to the driver > > > > > using it there is no API change. > > > > > > > > Somehow I think the likelyhood is that I am misreading the patch. > > > > > > > > I thought that before this patch drivers we had to register a > > > > syscon device to bind to this driver, which was fine for the first > > > > use-cases of syscon as it wasn't required too early during boot. > > > > However, now there are use-cases where systems require access to > > > > syscon registers eariler in boot we require a means to obtain > > > > access prior to device probing. I thought this patch not only > > > > provides that possibilty, but also leaves in the ability to register direct from > DT. > > > > > > Right, it does provide the ability to have syscon before devices are > > > registered, I missed that part. > > > > > > > > In contrast, this patch introduces a new > > > > > of_syscon_{un,}register() interface that would get removed after > > > > > the the above has been implemented, causing extra churn for any > > > > > driver that also wants to provide a regmap-like interface. > > > > > > > > When will we ever not have to register syscon? > > > > > > The idea is that we implicitly register the syscon block when > > > someone calls syscon_regmap_lookup_by_compatible or > > > syscon_regmap_lookup_by_phandle and then return a reference to that > > > new syscon. When another driver looks up the same device node, we > > > just pass a reference to the existing syscon. > > > > Doesn't sound too unreasonable. So how about instead of exporting > > these new of_syscon_{un,}register() calls, we make them static and > > call them from syscon_regmap_lookup_by_{phandle,compatible}? > > Yes, that would be a good start. We should think about whether we want to remove > the existing DT probing at the same time, since it becomes unused, and we might > want to move the code to drivers/base/regmap_*.c at some point. > OK, I am working on these two parts. Once code is in proper form and tested on our setup I will post here. Thanks, Pankaj > Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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