linux-kernel - Re: [PATCH v4 05/10] drm/bridge: synopsis: Fix to properly handle HPD

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Message-Id: <FBF48545-3509-42AA-AED5-A89BB5B1D9CD@goldelico.com>
Date:   Mon, 27 Sep 2021 19:53:45 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Paul Cercueil <paul@...pouillou.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Harry Wentland <harry.wentland@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Paul Boddie <paul@...die.org.uk>, devicetree@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        letux-kernel@...nphoenux.org, Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v4 05/10] drm/bridge: synopsis: Fix to properly handle HPD



> Am 27.09.2021 um 19:00 schrieb Maxime Ripard <maxime@...no.tech>:
> 
> Hi,
> 
> On Mon, Sep 27, 2021 at 06:44:23PM +0200, H. Nikolaus Schaller wrote:
>> It appears that dw-hdmi plugin detection is not properly
>> propagated unless we call drm_kms_helper_hotplug_event().
>> 
>> Maybe drm_bridge_hpd_notify should have been setup to
>> call this.
>> 
>> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
>> ---
>> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 2 ++
>> 1 file changed, 2 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> index f082e14320e1..edea04f80576 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>> @@ -3018,6 +3018,8 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
>> 		if (hdmi->bridge.dev) {
>> 			drm_helper_hpd_irq_event(hdmi->bridge.dev);
>> 			drm_bridge_hpd_notify(&hdmi->bridge, status);
>> +
>> +			drm_kms_helper_hotplug_event(hdmi->bridge.dev);
> 
> drm_kms_helper_hotplug_event is already called from drm_helper_hpd_irq_event

Ah, now I see. It should be called but is not for some unkown
condition (poll disabled? changed = false?).

It may also be a leftover from the attempt to make it work with
the builtin dw-hdmi connector.

Will check for v5.

BR and thanks,
Nikolaus