linux-kernel - Re: [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the detect function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201108104742.GA1161483@ravnborg.org>
Date:   Sun, 8 Nov 2020 11:47:42 +0100
From:   Sam Ravnborg <sam@...nborg.org>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Fabio Estevam <fabio.estevam@...escale.com>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonathan Liu <net147@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        David Airlie <airlied@...ux.ie>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Andrzej Hajda <a.hajda@...sung.com>,
        linux-rockchip@...ts.infradead.org,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Liu Ying <victor.liu@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the
 detect function

Hi Russell,

On Sun, Nov 08, 2020 at 09:57:25AM +0000, Russell King - ARM Linux admin wrote:
> On Sun, Nov 08, 2020 at 10:53:22AM +0100, Sam Ravnborg wrote:
> > Russell,
> > 
> > On Sat, Oct 31, 2020 at 07:17:47PM +1100, Jonathan Liu wrote:
> > > It has been observed that resetting force in the detect function can
> > > result in the PHY being powered down in response to hot-plug detect
> > > being asserted, even when the HDMI connector is forced on.
> > > 
> > > Enabling debug messages and adding a call to dump_stack() in
> > > dw_hdmi_phy_power_off() shows the following in dmesg:
> > > [  160.637413] dwhdmi-rockchip ff940000.hdmi: EVENT=plugin
> > > [  160.637433] dwhdmi-rockchip ff940000.hdmi: PHY powered down in 0 iterations
> > > 
> > > Call trace:
> > > dw_hdmi_phy_power_off
> > > dw_hdmi_phy_disable
> > > dw_hdmi_update_power
> > > dw_hdmi_detect
> > > dw_hdmi_connector_detect
> > > drm_helper_probe_detect_ctx
> > > drm_helper_hpd_irq_event
> > > dw_hdmi_irq
> > > irq_thread_fn
> > > irq_thread
> > > kthread
> > > ret_from_fork
> > > 
> > > Fixes: 381f05a7a842 ("drm: bridge/dw_hdmi: add connector mode forcing")
> > > Signed-off-by: Jonathan Liu <net147@...il.com>
> > 
> > you are the original author of this code - any comments on this patch?
> 
> No further comments beyond what has already been discussed, and the
> long and short of it is it's been so long that I don't remember why
> that code was there. Given that, I'm not even in a position to ack
> the change. Sorry.
Thanks for the quick reply.

Given that this fixes a problem for Jonathan I will apply this to -fixes
if there is no other feedback the next couple of days.
If it introduces regression we can take it from there.

Jonathan - please ping me if I forget.

	Sam