Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate".

From	Andrzej Hajda <a.hajda@samsung.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate".
Date	2016-10-11 12:00 +0200
Message-ID	<sr20N-52o-7@gated-at.bofh.it> (permalink)
References	(1 earlier) <sqE89-7l8-5@gated-at.bofh.it> <sqFxf-82E-3@gated-at.bofh.it> <sr0V3-4mQ-1@gated-at.bofh.it> <sr20N-52o-9@gated-at.bofh.it> <sr1Hr-4Wf-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 11.10.2016 11:33, Jani Nikula wrote:
> On Tue, 11 Oct 2016, "Sun, Jing A" <jing.a.sun@intel.com> wrote:
>> It's needed that DRM Driver module could be removed and reloaded after
>> kernel booting on the projects that I have been working on, and I hope
>> such module type change could be accepted. Looks like Iwai has similar
>> change request as well. Would you please review it and let us know if
>> any concerns?
> Looking at the Kconfig, selecting CONFIG_DRM_MIPI_DSI is against the
> recommendations of Documentation/kbuild/kconfig-language.txt:
>
> 	select should be used with care. select will force
> 	a symbol to a value without visiting the dependencies.
> 	By abusing select you are able to select a symbol FOO even
> 	if FOO depends on BAR that is not set.
> 	In general use select only for non-visible symbols
> 	(no prompts anywhere) and for symbols with no dependencies.
> 	That will limit the usefulness but on the other hand avoid
> 	the illegal configurations all over.

All existing drivers which selects DRM_MIPI_DSI also depends on DRM.
So the dependency is always true. I am not sure if it could not change in
the future, but in such case mipi_dsi bus should be completely detached from
DRM framework, I hope we have not such case yet :)

>
> Indeed, you may end up with CONFIG_DRM_MIPI_DSI=y and CONFIG_DRM=m,
> which violates DRM_MIPI_DSI dependency on CONFIG_DRM. This is broken and
> should be fixed. The suggested patch does *not* fix this issue.

At the moment it should not be possible.

Regards
Andrzej

Thread

[PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to  "tristate". "Sun, Jing A" <jing.a.sun@intel.com> - 2016-10-10 09:40 +0200
  Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Jani Nikula <jani.nikula@linux.intel.com> - 2016-10-10 10:30 +0200
    Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Takashi Iwai <tiwai@suse.de> - 2016-10-10 12:00 +0200
      RE: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to  "tristate". "Sun, Jing A" <jing.a.sun@intel.com> - 2016-10-11 10:50 +0200
        Re:  [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Andrzej Hajda <a.hajda@samsung.com> - 2016-10-11 11:20 +0200
        RE: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Jani Nikula <jani.nikula@linux.intel.com> - 2016-10-11 11:40 +0200
          Re:  [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Andrzej Hajda <a.hajda@samsung.com> - 2016-10-11 12:00 +0200
            RE: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to  "tristate". "Sun, Jing A" <jing.a.sun@intel.com> - 2016-10-12 05:10 +0200
              Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to  "tristate". Daniel Vetter <daniel@ffwll.ch> - 2016-10-12 09:00 +0200
                RE: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to  "tristate". "Sun, Jing A" <jing.a.sun@intel.com> - 2016-10-12 11:10 +0200
                RE: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Jani Nikula <jani.nikula@linux.intel.com> - 2016-10-12 13:00 +0200
          Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Emil Velikov <emil.l.velikov@gmail.com> - 2016-10-12 13:30 +0200
            Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Jani Nikula <jani.nikula@linux.intel.com> - 2016-10-12 16:30 +0200

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