From: John Stultz <john.stultz@linaro.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
David Airlie <airlied@linux.ie>,
Archit Taneja <architt@codeaurora.org>,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
Lars-Peter Clausen <lars@metafoo.de>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>
Subject: Re: [RFC][PATCH 2/3] drm/bridge: adv7511: Add 200ms delay on power-on
Date: Tue, 22 Nov 2016 10:07:53 -0800 [thread overview]
Message-ID: <CALAqxLXpYfnqPaxRNpiTqo25xyN3ENLPd3L8nfRoi0Gk5xDTyQ@mail.gmail.com> (raw)
In-Reply-To: <CALAqxLUMCD0PywzYJPn7OccM-xbyP=M0zRJX6+MfFtHBSSGvcA@mail.gmail.com>
On Tue, Nov 22, 2016 at 9:38 AM, John Stultz <john.stultz@linaro.org> wrote:
>
> Interestingly, without the msleep added in this patch, removing the
> wait_event_interruptible_timeout() method in adv7511_wait_for_edid()
> and using the polling loop seems to make things just as reliable. So
> maybe something is off with the irq handling here instead?
Ahhhh.. So I think the trouble here is the that when we fail waiting
for the irq, the backtrace is as follows:
[ 8.318654] [<ffffff8008087c28>] dump_backtrace+0x0/0x1a0
[ 8.318661] [<ffffff8008087ddc>] show_stack+0x14/0x20
[ 8.318671] [<ffffff80084344f0>] dump_stack+0x90/0xb0
[ 8.318680] [<ffffff8008534650>] adv7511_get_edid_block+0x2c8/0x320
[ 8.318687] [<ffffff80085214a8>] drm_do_get_edid+0x78/0x280
[ 8.318693] [<ffffff8008534728>] adv7511_get_modes+0x80/0xd8
[ 8.318700] [<ffffff8008534794>] adv7511_connector_get_modes+0x14/0x20
[ 8.318710] [<ffffff8008500a54>]
drm_helper_probe_single_connector_modes+0x2bc/0x500
[ 8.318718] [<ffffff800850e400>] drm_fb_helper_hotplug_event+0x130/0x188
[ 8.318726] [<ffffff800850ee68>] drm_fbdev_cma_hotplug_event+0x10/0x20
[ 8.318733] [<ffffff8008535718>] kirin_fbdev_output_poll_changed+0x20/0x58
[ 8.318740] [<ffffff8008500cc0>] drm_kms_helper_hotplug_event+0x28/0x38
[ 8.318748] [<ffffff80085010d8>] drm_helper_hpd_irq_event+0x138/0x180
[ 8.318754] [<ffffff8008533850>] adv7511_irq_process+0x78/0xd8
[ 8.318761] [<ffffff80085338c4>] adv7511_irq_handler+0x14/0x28
[ 8.318769] [<ffffff8008100060>] irq_thread_fn+0x28/0x68
[ 8.318775] [<ffffff8008100350>] irq_thread+0x128/0x1e8
[ 8.318782] [<ffffff80080d2e68>] kthread+0xd0/0xe8
[ 8.318788] [<ffffff8008082e80>] ret_from_fork+0x10/0x50
So we're actually in irq handling the hotplug interrupt, which is why
we never get the irq notification when the edid is read.
I suspect we need to use a workqueue to do the hotplug handling out of irq.
thanks
-john
next prev parent reply other threads:[~2016-11-22 18:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-22 0:37 [RFC][PATCH 0/3] adv7511 EDID probing improvements John Stultz
2016-11-22 0:37 ` [RFC][PATCH 1/3] drm/bridge: adv7511: Rework adv7511_power_on/off() so they can be reused internally John Stultz
2016-11-22 8:14 ` Laurent Pinchart
2016-11-22 8:16 ` John Stultz
2016-11-22 8:27 ` Laurent Pinchart
2016-11-22 17:25 ` John Stultz
2016-11-22 17:38 ` Laurent Pinchart
2016-11-22 17:44 ` John Stultz
2016-11-22 19:46 ` John Stultz
2016-11-23 3:50 ` Archit Taneja
2016-11-28 18:44 ` John Stultz
2016-11-22 0:37 ` [RFC][PATCH 2/3] drm/bridge: adv7511: Add 200ms delay on power-on John Stultz
2016-11-22 8:25 ` Laurent Pinchart
2016-11-22 17:38 ` John Stultz
2016-11-22 18:07 ` John Stultz [this message]
2016-11-22 18:23 ` Laurent Pinchart
2016-11-22 18:53 ` John Stultz
2016-11-23 7:55 ` Daniel Vetter
2016-11-25 0:23 ` Laurent Pinchart
2016-11-25 6:33 ` Daniel Vetter
2016-11-22 0:37 ` [RFC][PATCH 3/3] drm/bridge: adv7511: Enable HPD interrupts to support hotplug and improve monitor detection John Stultz
2016-11-22 8:29 ` Laurent Pinchart
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