From: Stephen Boyd <swboyd@chromium.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
Daniel Vetter <daniel.vetter@ffwll.ch>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Rob Clark <robdclark@gmail.com>,
Russell King <rmk+kernel@arm.linux.org.uk>
Subject: Re: [PATCH v2 02/34] component: Introduce the aggregate bus_type
Date: Thu, 7 Oct 2021 16:11:40 -0400 [thread overview]
Message-ID: <CAE-0n532XYgT=dTTCyLcwikvxgUyGi=TcybDh=v3wQTNb=wqyw@mail.gmail.com> (raw)
In-Reply-To: <CAE-0n50YqKr1nKy-4WaxsfuwPiJ5kZcf46t-U_4i-TpfXzOX1g@mail.gmail.com>
Quoting Stephen Boyd (2021-10-07 11:40:07)
> Quoting Saravana Kannan (2021-10-06 20:07:11)
> > On Wed, Oct 6, 2021 at 12:38 PM Stephen Boyd <swboyd@chromium.org> wrote:
> > > diff --git a/drivers/base/component.c b/drivers/base/component.c
> > > index 0a41bbe14981..d99e99cabb99 100644
> > > --- a/drivers/base/component.c
> > > +++ b/drivers/base/component.c
> [...]
> > > + continue;
> > > +
> > > + /* Matches put in component_del() */
> > > + get_device(&adev->dev);
> > > + c->link = device_link_add(&adev->dev, c->dev,
> > > + DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
> >
> > Remove the STATELESS flag and you'll get a bunch of other stuff done for free:
>
> I tried that and it didn't work for me. The aggregate device never
> probed and I was left with no display. Let me see if I can reproduce it
> with logging to provide more details.
This patch fixes it (whitespace damaged sorry).
----8<----
diff --git a/drivers/base/component.c b/drivers/base/component.c
index 65042c9f8a42..43cac9ed70b7 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -202,7 +202,7 @@ static int find_components(struct aggregate_device *adev)
/* Matches put in component_del() */
get_device(&adev->dev);
c->link = device_link_add(&adev->dev, c->dev,
- DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
+ DL_FLAG_PM_RUNTIME);
c->adev = adev;
}
@@ -749,7 +749,9 @@ static int __component_add(struct device *dev,
const struct component_ops *ops,
mutex_unlock(&component_mutex);
/* Try to bind */
- return bus_rescan_devices(&aggregate_bus_type);
+ bus_rescan_devices(&aggregate_bus_type);
+
+ return 0;
}
/**
The important part is ignoring the return value of bus_rescan_devices().
It's a cycle problem. The last component is probing and calling
component_add() in its probe function. The call to component_add() is
trying to probe the aggregate device now that all components are added.
But when it tries to probe the aggregate device it sees that a supplier,
which is this component calling compnent_add(), hasn't been probed yet,
so it returns -EPROBE_DEFER. That is passed up to the component and it
defers probe.
I don't think the component device cares at all about the aggregate
device being able to probe or not. We should be able to ignore the
return value of bus_rescan_devices() in component_add(). I'll add a
comment to the code here so it's more obvious.
next prev parent reply other threads:[~2021-10-07 20:11 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 19:37 [PATCH v2 00/34] component: Make into an aggregate bus Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 01/34] component: Introduce struct aggregate_device Stephen Boyd
2021-10-07 1:17 ` Laurent Pinchart
2021-10-07 18:36 ` Stephen Boyd
2021-10-13 12:22 ` Daniel Vetter
2021-10-13 19:49 ` Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 02/34] component: Introduce the aggregate bus_type Stephen Boyd
2021-10-06 22:42 ` kernel test robot
2021-10-07 3:07 ` Saravana Kannan
2021-10-07 18:40 ` Stephen Boyd
2021-10-07 20:11 ` Stephen Boyd [this message]
2021-10-08 1:10 ` Saravana Kannan
2021-10-08 1:24 ` Stephen Boyd
2021-10-08 1:32 ` Saravana Kannan
2021-10-08 1:37 ` Stephen Boyd
2021-10-07 5:37 ` Greg Kroah-Hartman
2021-10-07 20:42 ` Stephen Boyd
2021-10-14 13:27 ` Daniel Vetter
2021-10-06 19:37 ` [PATCH v2 03/34] component: Move struct aggregate_device out to header file Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 04/34] drm/msm: Migrate to aggregate driver Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 05/34] component: Add {bind,unbind}_component() ops that take aggregate device Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 06/34] drm/of: Add a drm_of_aggregate_probe() API Stephen Boyd
2021-10-06 22:28 ` kernel test robot
2021-10-06 22:36 ` kernel test robot
2021-10-06 19:37 ` [PATCH v2 07/34] drm/komeda: Migrate to aggregate driver Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 08/34] drm/arm/hdlcd: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 09/34] drm/malidp: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 10/34] drm/armada: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 11/34] drm/etnaviv: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 12/34] drm/kirin: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 13/34] drm/exynos: " Stephen Boyd
2021-10-06 19:37 ` [PATCH v2 14/34] drm/imx: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 15/34] drm/ingenic: " Stephen Boyd
2021-10-07 21:29 ` Paul Cercueil
2021-10-06 19:38 ` [PATCH v2 16/34] drm/mcde: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 17/34] drm/mediatek: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 18/34] drm/meson: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 19/34] drm/omap: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 20/34] drm/rockchip: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 21/34] drm/sti: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 22/34] drm/sun4i: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 23/34] drm/tilcdc: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 24/34] drm/vc4: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 25/34] drm/zte: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 26/34] iommu/mtk: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 27/34] mei: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 28/34] power: supply: ab8500: " Stephen Boyd
2021-10-13 16:24 ` Sebastian Reichel
2021-10-06 19:38 ` [PATCH v2 29/34] fbdev: omap2: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 30/34] sound: hdac: " Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 31/34] ASoC: codecs: wcd938x: " Stephen Boyd
2021-10-07 12:35 ` Mark Brown
2021-10-06 19:38 ` [PATCH v2 32/34] component: Get rid of drm_of_component_probe() Stephen Boyd
2021-10-06 19:38 ` [PATCH v2 33/34] component: Remove component_master_ops and friends Stephen Boyd
2021-10-06 23:19 ` kernel test robot
2021-10-06 19:38 ` [PATCH v2 34/34] component: Remove all references to 'master' Stephen Boyd
2021-10-07 10:16 ` [PATCH v2 00/34] component: Make into an aggregate bus Andrzej Hajda
2021-10-07 20:46 ` Stephen Boyd
2021-10-13 12:14 ` Daniel Vetter
[not found] ` <CAHp75VdLg-rBjCDGEwgkY6QDbFGW0of4SjSmp08FXXRN_raQtQ@mail.gmail.com>
2021-10-07 12:33 ` Andrzej Hajda
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