From: Daniel Vetter <daniel@ffwll.ch>
To: Andrzej Hajda <a.hajda@samsung.com>
Cc: "Peter Rosin" <peda@axentia.se>,
linux-kernel@vger.kernel.org,
"Archit Taneja" <architt@codeaurora.org>,
"Laurent Pinchart" <Laurent.pinchart@ideasonboard.com>,
"David Airlie" <airlied@linux.ie>,
"Peter Senna Tschudin" <peter.senna@collabora.com>,
"Martin Donnelly" <martin.donnelly@ge.com>,
"Martyn Welch" <martyn.welch@collabora.co.uk>,
"Gustavo Padovan" <gustavo@padovan.org>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Sean Paul" <seanpaul@chromium.org>,
"Inki Dae" <inki.dae@samsung.com>,
"Joonyoung Shim" <jy0922.shim@samsung.com>,
"Seung-Woo Kim" <sw0312.kim@samsung.com>,
"Kyungmin Park" <kyungmin.park@samsung.com>,
"Kukjin Kim" <kgene@kernel.org>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
"CK Hu" <ck.hu@mediatek.com>,
"Philipp Zabel" <p.zabel@pengutronix.de>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Rob Clark" <robdclark@gmail.com>,
"Sandy Huang" <hjc@rock-chips.com>,
"Heiko Stübner" <heiko@sntech.de>,
"Benjamin Gaignard" <benjamin.gaignard@linaro.org>,
"Vincent Abriou" <vincent.abriou@st.com>,
dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org,
linux-mediatek@lists.infradead.org,
linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
linux-renesas-soc@vger.kernel.org,
linux-rockchip@lists.infradead.org, "Jyri Sarha" <jsarha@ti.com>,
"Daniel Vetter" <daniel@ffwll.ch>
Subject: Re: [PATCH v2 26/26] drm/bridge: establish a link between the bridge supplier and consumer
Date: Mon, 7 May 2018 15:53:41 +0200 [thread overview]
Message-ID: <20180507135341.GI12521@phenom.ffwll.local> (raw)
In-Reply-To: <4cdcd215-8caf-e045-a478-f438f128c9f2@samsung.com>
On Mon, May 07, 2018 at 02:59:45PM +0200, Andrzej Hajda wrote:
> On 04.05.2018 15:52, Peter Rosin wrote:
> > If the bridge supplier is unbound, this will bring the bridge consumer
> > down along with the bridge. Thus, there will no longer linger any
> > dangling pointers from the bridge consumer (the drm_device) to some
> > non-existent bridge supplier.
>
> I understand rationales behind this patch, but it is another step into
> making drm_dev one big driver with subcomponents, where drm will work
> only if every subcomponent is working/loaded. Do we need to go this way?
> In case of many platforms such approach results in display turned on
> very late on boot for example due to late initialization of some
> regulator exposed by some i2c device, which is used by hdmi bridge. And
> this hdmi bridge is just to provide alternative(rarely used) display
> path, the main display path would work anyway.
>
> So the main question to drm maintainers is about evolution of bridges,
> if drm_bridges should become mandatory components of drm device or they
> could be added/removed dynamically?
This is already the case. You currently cannot hotplug a drm_bridge,
everything must be present. I don't think it makes sense to change that
until we have physically hotpluggable drm_bridges in real hardware. I
definitely don't want to refcount stuff to work around driver load
bonghits on DT platforms, because refcounting is way too hard to get right
:-)
Afaik there's out-of-tree patches to solve 99% of the driver load fun on
DT platforms, but because it's not a 100% solution it's blocked since
forever.
-Daniel
>
> Regards
> Andrzej
>
>
> >
> > Signed-off-by: Peter Rosin <peda@axentia.se>
> > ---
> > drivers/gpu/drm/drm_bridge.c | 18 ++++++++++++++++++
> > include/drm/drm_bridge.h | 2 ++
> > 2 files changed, 20 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> > index 78d186b6831b..0259f0a3ff27 100644
> > --- a/drivers/gpu/drm/drm_bridge.c
> > +++ b/drivers/gpu/drm/drm_bridge.c
> > @@ -26,6 +26,7 @@
> > #include <linux/mutex.h>
> >
> > #include <drm/drm_bridge.h>
> > +#include <drm/drm_device.h>
> > #include <drm/drm_encoder.h>
> >
> > #include "drm_crtc_internal.h"
> > @@ -127,12 +128,25 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
> > if (bridge->dev)
> > return -EBUSY;
> >
> > + if (encoder->dev->dev != bridge->odev) {
> > + bridge->link = device_link_add(encoder->dev->dev,
> > + bridge->odev, 0);
> > + if (!bridge->link) {
> > + dev_err(bridge->odev, "failed to link bridge to %s\n",
> > + dev_name(encoder->dev->dev));
> > + return -EINVAL;
> > + }
> > + }
> > +
> > bridge->dev = encoder->dev;
> > bridge->encoder = encoder;
> >
> > if (bridge->funcs->attach) {
> > ret = bridge->funcs->attach(bridge);
> > if (ret < 0) {
> > + if (bridge->link)
> > + device_link_del(bridge->link);
> > + bridge->link = NULL;
> > bridge->dev = NULL;
> > bridge->encoder = NULL;
> > return ret;
> > @@ -159,6 +173,10 @@ void drm_bridge_detach(struct drm_bridge *bridge)
> > if (bridge->funcs->detach)
> > bridge->funcs->detach(bridge);
> >
> > + if (bridge->link)
> > + device_link_del(bridge->link);
> > + bridge->link = NULL;
> > +
> > bridge->dev = NULL;
> > }
> >
> > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> > index b656e505d11e..804189c63a4c 100644
> > --- a/include/drm/drm_bridge.h
> > +++ b/include/drm/drm_bridge.h
> > @@ -261,6 +261,7 @@ struct drm_bridge_timings {
> > * @list: to keep track of all added bridges
> > * @timings: the timing specification for the bridge, if any (may
> > * be NULL)
> > + * @link: drm consumer <-> bridge supplier
> > * @funcs: control functions
> > * @driver_private: pointer to the bridge driver's internal context
> > */
> > @@ -271,6 +272,7 @@ struct drm_bridge {
> > struct drm_bridge *next;
> > struct list_head list;
> > const struct drm_bridge_timings *timings;
> > + struct device_link *link;
> >
> > const struct drm_bridge_funcs *funcs;
> > void *driver_private;
>
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
next prev parent reply other threads:[~2018-05-07 13:53 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 13:51 [PATCH v2 00/26] device link, bridge supplier <-> drm device Peter Rosin
2018-05-04 13:51 ` [PATCH v2 01/26] drm/bridge: allow optionally specifying an owner .odev device Peter Rosin
2018-05-09 15:08 ` Andrzej Hajda
2018-05-09 15:53 ` Peter Rosin
2018-05-09 22:21 ` Peter Rosin
2018-05-10 7:00 ` Andrzej Hajda
2018-05-04 13:51 ` [PATCH v2 02/26] drm/bridge: adv7511: provide " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 03/26] drm/bridge/analogix: core: specify the owner .odev of the bridge Peter Rosin
2018-05-04 13:51 ` [PATCH v2 04/26] drm/bridge: analogix-anx78xx: provide an owner .odev device Peter Rosin
2018-05-04 13:51 ` [PATCH v2 05/26] drm/bridge: cdns-dsi: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 06/26] drm/bridge: vga-dac: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 07/26] drm/bridge: lvds-encoder: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 08/26] drm/bridge: megachips-stdpxxxx-ge-b850v3-fw: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 09/26] drm/bridge: nxp-ptn3460: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 10/26] drm/bridge: panel: " Peter Rosin
2018-05-08 6:51 ` Jyri Sarha
2018-05-08 7:58 ` Peter Rosin
2018-05-08 10:30 ` Daniel Vetter
2018-05-08 12:25 ` Jyri Sarha
2018-05-04 13:51 ` [PATCH v2 11/26] drm/bridge: ps8622: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 12/26] drm/bridge: sii902x: " Peter Rosin
2018-05-04 13:51 ` [PATCH v2 13/26] drm/bridge: sii9234: " Peter Rosin
2018-05-04 13:52 ` [PATCH v2 14/26] drm/bridge: sii8620: " Peter Rosin
2018-05-04 13:52 ` [PATCH v2 15/26] drm/bridge: synopsys: provide an owner .odev device for the bridges Peter Rosin
2018-05-04 13:52 ` [PATCH v2 16/26] drm/bridge: tc358767: provide an owner .odev device Peter Rosin
2018-05-04 13:52 ` [PATCH v2 17/26] drm/bridge: thc63lvd1024: " Peter Rosin
2018-05-04 13:52 ` [PATCH v2 18/26] drm/bridge: ti-tfp410: " Peter Rosin
2018-05-04 13:52 ` [PATCH v2 19/26] drm/exynos: mic: provide an owner .odev device for the bridge Peter Rosin
2018-05-04 13:52 ` [PATCH v2 20/26] drm/mediatek: hdmi: " Peter Rosin
2018-05-04 13:52 ` [PATCH v2 21/26] drm/msm: specify the owner .odev of the bridges Peter Rosin
2018-05-04 13:52 ` [PATCH v2 22/26] drm/rcar-du: lvds: provide an owner .odev device for the bridge Peter Rosin
2018-05-04 13:52 ` [PATCH v2 23/26] drm/sti: provide an owner .odev device for the bridges Peter Rosin
2018-05-04 13:52 ` [PATCH v2 24/26] drm/bridge: remove the .of_node member Peter Rosin
2018-05-04 13:52 ` [PATCH v2 25/26] drm/bridge: require the owner .odev to be filled in on drm_bridge_add/attach Peter Rosin
2018-05-10 7:13 ` Andrzej Hajda
2018-05-04 13:52 ` [PATCH v2 26/26] drm/bridge: establish a link between the bridge supplier and consumer Peter Rosin
2018-05-07 12:59 ` Andrzej Hajda
2018-05-07 13:43 ` Peter Rosin
2018-05-08 9:03 ` Andrzej Hajda
2018-05-07 13:53 ` Daniel Vetter [this message]
2018-05-08 6:36 ` Andrzej Hajda
2018-05-10 8:10 ` Andrzej Hajda
2018-05-11 7:37 ` Peter Rosin
2018-05-14 16:28 ` Daniel Vetter
2018-05-14 20:40 ` Peter Rosin
2018-05-15 10:22 ` Daniel Vetter
2018-05-15 11:09 ` Peter Rosin
2018-05-16 9:31 ` Daniel Vetter
2018-05-07 13:56 ` [PATCH v2 00/26] device link, bridge supplier <-> drm device Daniel Vetter
2018-05-07 14:09 ` Peter Rosin
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