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Date: Mon, 16 Dec 2013 16:48:44 +0000 From: Lee Jones <lee.jones@...aro.org> To: Laszlo Papp <lpapp@....org> Cc: sameo@...ux.intel.com, LKML <linux-kernel@...r.kernel.org> Subject: Re: Simple MFD driver example > > Please refrain from top posting. > > > > Responses should appear under quoted lines, which they reference. > > I intentionally did not reply to a specific quote, but to the email as a whole! Then you should have placed your response underneath the whole email, not on top. If you're going to continue contributing to Mainline, please find yourself a better email client. I assume you're using Gmail at the moment, which is not suitable for this purpose. > >> >> I have been trying to write about 50-100 LOC for 1-2 weeks now. I have > >> >> a fairly simple use case for MFD where I need to have gpio and hwmon > >> >> functionality for a GPIO. > >> >> > >> >> I read the mfd drivers inside and out by now, but it looks a bit > >> >> inconsistent to me. I am not sure what to follow etc. The > >> >> documentation seems to be virtually missing which makes my life and > >> >> involvement even more difficult. :( > >> >> > >> >> May I ask for some pointer how to do all this? It would be nice to see > >> >> a minimal example where the parent does not do anything else than just > >> >> enumerating the sub-device drivers. Is that possible with an empty > >> >> probe callback? > >> >> > >> >> If I understand the regmap correctly (again, it is possible I do not), > >> >> then I would not need this. But in general, it is really hard to deal > >> >> with the linux kernel in this regard when basic documentations are > >> >> missing. > >> >> > >> >> I hope this would change over time for the posterity. It is a pity > >> >> that contributors do not join probably due to this. It is a bit > >> >> chaotic, but I hope it can be changed in the future. > >> >> > >> >> Apologies for my frustration... > >> > > >> > Due to the nature of the MFD subsystem, there isn't a simple use-case > >> > which you can use as a template. It's completely dependent on the > >> > device you are trying to enable. There are lots of well written > >> > drivers in the subsystem that you can use as good examples though. > > > >> Well, if you ask me the MFD subsystem is underdocumented, and there is > >> some inconsistency between the drivers. It is hard to take any of them > >> as a starting point, at least for me. > > > > Feel free to write some. I'm always happy to take helpful patches. > > I am not the right person for documentating everything here, > especially when I do not even understand basics... I am just trying to > figure out my way here. It was more like a hint that this area could > take some love. At least, I would personally appreciate it a lot. It > is currently somewhat difficult to get involved. There isn't any documentation that would help you I fear. I'm trying to help you, but you haven't answered my previous question. Do you have a datasheet for the device that you're trying to enable? -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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