From: Zev Weiss <firstname.lastname@example.org> To: Jeremy Kerr <email@example.com> Cc: Andrew Jeffery <firstname.lastname@example.org>, "email@example.com" <firstname.lastname@example.org>, Eddie James <email@example.com> Subject: Re: [PATCH RFC] Specifying default-disabled devices Date: Fri, 10 Sep 2021 05:28:36 +0000 [thread overview] Message-ID: <20210910052835.GF17315@packtop> (raw) In-Reply-To: <firstname.lastname@example.org> On Thu, Sep 09, 2021 at 09:04:05PM PDT, Jeremy Kerr wrote: >Hi Zev, > >> However, I think I may have spoken too soon regarding the relative >> simplicity of implementing it -- from a quick glance at it, I think >> I'd want to take of_device_is_available() and split it into some >> variants for strictly-okay and okay-or-reserved (and similarly for >> of_get_next_available_child()). The problem there is that there are >> currently circa 200 callers of those functions scattered thoughout the >> tree, and auditing each of them individually to determine which of >> those semantics is actually appropriate in each case seems...a bit >> daunting. > >I think you should be OK, if you stage it this way: > > - add status = "reserved" to your device tree; this will supress the > automatic binding right away. With the current code, all it cares > about is status = "okay" (or "ok"), so you'll at least keep the > device quiesced. > > with that, there won't be an easy way to initiate the driver probe, > but maybe that's OK for your use-case if you're doing the bind > manually. > From some grepping around it looks like the only check is for "okay"/"ok", and nothing actually checks for "disabled", so I'd think any non-OK string (including "reserved") would end up being equivalent to "disabled", and hence result in the device node not being instantiated at all. (A quick test appears to confirm; with status = "reserved", an attempt to bind via sysfs fails with ENODEV.) Zev
next prev parent reply other threads:[~2021-09-10 5:29 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-10 2:24 Zev Weiss 2021-09-10 2:33 ` Jeremy Kerr 2021-09-10 3:49 ` Zev Weiss 2021-09-10 4:04 ` Jeremy Kerr 2021-09-10 5:28 ` Zev Weiss [this message] 2021-09-10 7:59 ` Jeremy Kerr 2021-09-10 8:35 ` Zev Weiss 2021-09-10 9:08 ` Jeremy Kerr 2021-09-10 21:59 ` Zev Weiss 2021-09-21 2:56 ` Zev Weiss 2021-09-10 4:36 ` Oliver O'Halloran
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