linux-kernel - Re: [PATCH v2 10/26] drm/bridge: panel: provide an owner .odev device

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Date:   Tue, 8 May 2018 15:25:51 +0300
From:   Jyri Sarha <jsarha@...com>
To:     Peter Rosin <peda@...ntia.se>, <linux-kernel@...r.kernel.org>
CC:     Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH v2 10/26] drm/bridge: panel: provide an owner .odev device

On 05/08/18 10:58, Peter Rosin wrote:
> On 2018-05-08 08:51, Jyri Sarha wrote:
>> On 05/04/18 16:51, Peter Rosin wrote:
>>> It gets rid of an #ifdef and the .of_node member is going away.
>>>
>>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>>> ---
>>>  drivers/gpu/drm/bridge/panel.c | 4 +---
>>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
>>> index 6d99d4a3beb3..f43d77b5ed20 100644
>>> --- a/drivers/gpu/drm/bridge/panel.c
>>> +++ b/drivers/gpu/drm/bridge/panel.c
>>> @@ -169,10 +169,8 @@ struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel,
>>>  	panel_bridge->connector_type = connector_type;
>>>  	panel_bridge->panel = panel;
>>>  
>>> +	panel_bridge->bridge.odev = panel->dev;
>> I am afraid this approach will eventually conflict with my lately
>> accepted patch[1].
> I don't see how? The links are refcounted. So, if there is one link
> each for the panel and bridge between the drm device and the panel
> device that link will simply get two references. If/when the panel
> device then goes away, the drm device will be brought down because
> of that link (with two references, but that is irrelevant). When
> the drm device is brought down, it will (presumably) bring down the
> bridge as well (which will fix the refcount as the bridge link is
> killed as part of that).
> 

I guess you are right. If everything is done correctly the both links
should get removed in the tear down situation and all should be fine.


> Or have you done some test and seen an actual problem?
> 

No testing, just a hunch.

BR,
Jyri

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