devicetree.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Maxime Ripard <maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org>
To: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
Cc: Jagan Teki
	<jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>,
	David Airlie <airlied-cv59FeDIM0c@public.gmane.org>,
	Daniel Vetter <daniel-/w4YWyX8dFk@public.gmane.org>,
	dri-devel
	<dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	linux-arm-kernel
	<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
	linux-kernel
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Jernej Skrabec <jernej.skrabec-gGgVlfcn5nU@public.gmane.org>,
	Michael Trimarchi
	<michael-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>,
	linux-sunxi <linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>,
	linux-amarula
	<linux-amarula-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
Subject: Re: Re: [PATCH v2 5/9] drm/sun4i: tcon_top: Register clock gates in probe
Date: Mon, 17 Jun 2019 16:54:20 +0200	[thread overview]
Message-ID: <20190617145420.e7yfrmmhdhift5id@flea> (raw)
In-Reply-To: <CAGb2v66RU=m0iA9VoBiYbake+mDoiiGcd5gGGXvNCBjhY2n+Dw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

[-- Attachment #1: Type: text/plain, Size: 1969 bytes --]

On Mon, Jun 17, 2019 at 09:01:33PM +0800, Chen-Yu Tsai wrote:
> On Mon, Jun 17, 2019 at 7:45 PM Maxime Ripard <maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org> wrote:
> >
> > On Fri, Jun 14, 2019 at 10:13:20PM +0530, Jagan Teki wrote:
> > > TCON TOP have clock gates for TV0, TV1, dsi and right
> > > now these are register during bind call.
> > >
> > > Of which, dsi clock gate would required during DPHY probe
> > > but same can miss to get since tcon top is not bound at
> > > that time.
> > >
> > > To solve, this circular dependency move the clock gate
> > > registration from bind to probe so-that DPHY can get the
> > > dsi gate clock on time.
> >
> > It's not really clear to me what the circular dependency is?
> >
> > if you have a chain that is:
> >
> > tcon-top +-> DSI
> >          +-> D-PHY
> >
> > There's no loop, right?
>
> Looking at how the DTSI patch structures things (without going into
> whether it is correct or accurate):
>
> The D-PHY is not part of the component graph. However it requests
> the DSI gate clock from the TCON-TOP.
>
> The TCON-TOP driver, in its current form, only registers the clocks
> it provides at component bind time. Thus the D-PHY can't successfully
> probe until the TCON-TOP has been bound.
>
> The DSI interface requires the D-PHY to bind. It will return -EPROBE_DEFER
> if it cannot request it. This in turn goes into the error path of
> component_bind_all, which unbinds all previous components.
>
> So it's actually
>
>     D-PHY -> TCON-TOP -> DSI
>       ^                   |
>       |--------------------
>
> I've not checked, but I suspect there's no possibility of having other
> drivers probe (to deal with deferred probing) within component_bind_all.
> Otherwise we shouldn't run into this weird circular dependency issue.
>

Ah, yes, that makes sense. It should be cleraer in the commit log then.

Thanks!
Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

  parent reply	other threads:[~2019-06-17 14:54 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-14 16:43 [PATCH v2 0/9] drm/sun4i: Allwinner R40 MIPI-DSI support Jagan Teki
2019-06-14 16:43 ` [PATCH v2 1/9] dt-bindings: display: Add TCON LCD compatible for R40 Jagan Teki
2019-07-09 14:49   ` Rob Herring
2019-06-14 16:43 ` [PATCH v2 2/9] drm/sun4i: tcon: Add TCON LCD support " Jagan Teki
2019-06-14 16:43 ` [PATCH v2 5/9] drm/sun4i: tcon_top: Register clock gates in probe Jagan Teki
     [not found]   ` <20190614164324.9427-6-jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
2019-06-16  5:31     ` Chen-Yu Tsai
     [not found]       ` <CAGb2v669MprYgy2wc_a7Kz8VpzzNGZxDxsj0z_Ujx5bV25+AWQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-17 10:29         ` Jagan Teki
     [not found]           ` <CAMty3ZDRYBPKrGQxAZoB+trFiDLJ5BxDfNUOnPzgd+UWcpwCoQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-18  7:19             ` Chen-Yu Tsai
2019-06-18  7:45               ` [linux-sunxi] " Jagan Teki
     [not found]                 ` <CAMty3ZBUrGEi+e62sFe7GkXinK3q076sGLwpEVz67qeoV+1ZeA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-18  7:53                   ` Chen-Yu Tsai
2019-06-18 10:34                     ` [linux-sunxi] " Jagan Teki
     [not found]                       ` <CAMty3ZA+hV_X0-=b83M3rDUhX=+g5RNC6EU-DzAS_pbvwc54FA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-18 10:54                         ` Chen-Yu Tsai
2019-06-20 16:24                           ` [linux-sunxi] " Jagan Teki
     [not found]                             ` <CAMty3ZC=Mn2po=98onX7WcmTGOmV0aK+ZT5bYFEFw+q+SqK4FA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-21  8:00                               ` Chen-Yu Tsai
2019-06-17 11:45     ` Maxime Ripard
2019-06-17 13:01       ` Chen-Yu Tsai
     [not found]         ` <CAGb2v66RU=m0iA9VoBiYbake+mDoiiGcd5gGGXvNCBjhY2n+Dw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-17 14:54           ` Maxime Ripard [this message]
2019-06-18  7:12         ` [linux-sunxi] " Jagan Teki
     [not found]           ` <CAMty3ZA0J+2fSRwX+tS-waJDLMyTOf6UY_1pHjXe0qOk5QuzrQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-06-18  7:23             ` Chen-Yu Tsai
2019-06-18  7:46               ` [linux-sunxi] " Jagan Teki
     [not found] ` <20190614164324.9427-1-jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
2019-06-14 16:43   ` [PATCH v2 3/9] ARM: dts: sun8i: r40: Use tcon top clock index macros Jagan Teki
2019-06-14 16:43   ` [PATCH v2 4/9] drm/sun4i: tcon_top: Use clock name " Jagan Teki
2019-06-14 16:43   ` [PATCH v2 6/9] dt-bindings: sun6i-dsi: Add R40 MIPI-DSI compatible (w/ A64 fallback) Jagan Teki
2019-07-09 14:50     ` Rob Herring
2019-06-14 16:43   ` [PATCH v2 7/9] dt-bindings: sun6i-dsi: Add R40 DPHY compatible (w/ A31 fallback) Jagan Teki
2019-07-09 16:16     ` Rob Herring
2019-06-14 16:43   ` [PATCH v2 8/9] ARM: dts: sun8i: r40: Add MIPI DSI pipeline Jagan Teki
2019-06-14 16:43   ` [DO NOT MERGE] [PATCH v2 9/9] ARM: dts: sun8i-r40: bananapi-m2-ultra: Enable Bananapi S070WV20-CT16 DSI panel Jagan Teki

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190617145420.e7yfrmmhdhift5id@flea \
    --to=maxime.ripard-ldxbnhwyfcjbdgjk7y7tuq@public.gmane.org \
    --cc=airlied-cv59FeDIM0c@public.gmane.org \
    --cc=daniel-/w4YWyX8dFk@public.gmane.org \
    --cc=devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org \
    --cc=jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org \
    --cc=jernej.skrabec-gGgVlfcn5nU@public.gmane.org \
    --cc=linux-amarula-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org \
    --cc=linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org \
    --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org \
    --cc=michael-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org \
    --cc=wens-jdAy2FN1RRM@public.gmane.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).