linux-kernel - Re: [PATCH v2 0/5] drm/vc4: hdmi: Fix CEC access while disabled

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Date:   Wed, 28 Jul 2021 14:52:24 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     DRI Development <dri-devel@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maxime Ripard <mripard@...nel.org>,
        Emma Anholt <emma@...olt.net>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Phil Elwell <phil@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Dom Cobley <dom@...pberrypi.com>,
        linux-rpi-kernel@...ts.infradead.org,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH v2 0/5] drm/vc4: hdmi: Fix CEC access while disabled

Hi Maxime

On Wed, 7 Jul 2021 at 10:23, Maxime Ripard <maxime@...no.tech> wrote:
>
> Hi,
>
> This series aims at fixing a complete and silent hang when one tries to use CEC
> while the display output is off.
>
> This can be tested with:
>
> echo off > /sys/class/drm/card0-HDMI-A-1/status
> cec-ctl --tuner -p 1.0.0.0
> cec-compliance
>
> This series addresses it by making sure the HDMI controller is powered up as
> soon as the CEC device is opened by the userspace.
>
> Let me know what you think,
> Maxime
>
> Changes from v1:
>   - More fixes
>   - Added a big warning if we try to access a register while the device is
>     disabled.
>   - Fixed the pre_crtc_configure error path
>
> Maxime Ripard (5):
>   drm/vc4: hdmi: Make sure the controller is powered up during bind
>   drm/vc4: hdmi: Rework the pre_crtc_configure error handling
>   drm/vc4: hdmi: Split the CEC disable / enable functions in two
>   drm/vc4: hdmi: Make sure the device is powered with CEC
>   drm/vc4: hdmi: Warn if we access the controller while disabled

Comment made on patch 1.

Patches 2-5:
Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>

  Dave

>
>  drivers/gpu/drm/vc4/vc4_hdmi.c      | 123 +++++++++++++++++++---------
>  drivers/gpu/drm/vc4/vc4_hdmi_regs.h |   6 ++
>  2 files changed, 89 insertions(+), 40 deletions(-)
>
> --
> 2.31.1
>