linux-kernel - Re: [PATCH v6 1/3] media: cec: expose HDMI connector to CEC dev mapping

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Message-ID: <c0007b51-5e9f-4788-b860-d0623e21013b@xs4all.nl>
Date:   Mon, 20 May 2019 12:25:13 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Dariusz Marcinkiewicz <darekm@...gle.com>,
        linux-media@...r.kernel.org, hans.verkuil@...co.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/3] media: cec: expose HDMI connector to CEC dev
 mapping

Hi Dariusz,

On 5/17/19 5:42 PM, Dariusz Marcinkiewicz wrote:
> This patch proposes to expose explicit mapping between HDMI connectors
> and /dev/cecX adapters to userland.
> 
> New structure with connector info (card number and connector id in case
> of DRM connectors) is added to cec_adapter. That connector info is expected
> to be provided when an adapter is created.
> 
> CEC notifier is extended so that it can be used to communicate the
> connector's info to CEC adapters' creators.
> 
> New ioctl, exposing connector info to userland, is added to /dev/cec.
> 
> Changes since v5:
>  - make the patch apply against the latest changes in the affected code
> Changes since v4:
>  - small tweaks + added documentation
> Changes since v3:
>  - cec_get_connter_conn takes connector_info as argument
> Changes since v2:
>  - cec_s_connector_info removed, the connector info is now passed to
>    cec_allocate_adapter
>  - updated commit message
> Changes since v1:
>  - removed the unnecessary event,
>  - extended cec_connctor_info to allow for various types of connectors.
> 
> Signed-off-by: Dariusz Marcinkiewicz <darekm@...gle.com>
> ---
>  Documentation/media/kapi/cec-core.rst         |   7 +-
>  Documentation/media/uapi/cec/cec-funcs.rst    |   1 +
>  .../uapi/cec/cec-ioc-adap-g-conn-info.rst     | 109 ++++++++++++++++++
>  .../display/amdgpu_dm/amdgpu_dm_mst_types.c   |   2 +-
>  drivers/gpu/drm/bridge/adv7511/adv7511_cec.c  |   3 +-
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c |   2 +-
>  drivers/gpu/drm/drm_dp_cec.c                  |  22 ++--
>  drivers/gpu/drm/i2c/tda9950.c                 |   3 +-
>  drivers/gpu/drm/i915/intel_dp.c               |   4 +-
>  drivers/gpu/drm/i915/intel_hdmi.c             |   6 +-
>  drivers/gpu/drm/nouveau/nouveau_connector.c   |   3 +-
>  drivers/gpu/drm/vc4/vc4_hdmi.c                |   8 +-
>  drivers/media/cec/cec-adap.c                  |  13 +++
>  drivers/media/cec/cec-api.c                   |  12 ++
>  drivers/media/cec/cec-core.c                  |   8 +-
>  drivers/media/cec/cec-notifier.c              |  20 +++-
>  drivers/media/cec/cec-pin.c                   |   2 +-
>  drivers/media/i2c/tc358743.c                  |   3 +-
>  .../media/platform/cros-ec-cec/cros-ec-cec.c  |   7 +-
>  drivers/media/platform/meson/ao-cec.c         |   6 +-
>  drivers/media/platform/s5p-cec/s5p_cec.c      |   6 +-
>  drivers/media/platform/seco-cec/seco-cec.c    |   8 +-
>  drivers/media/platform/sti/cec/stih-cec.c     |   6 +-
>  drivers/media/platform/stm32/stm32-cec.c      |   2 +-
>  drivers/media/platform/tegra-cec/tegra_cec.c  |   5 +-
>  drivers/media/platform/vivid/vivid-cec.c      |   2 +-
>  drivers/media/usb/pulse8-cec/pulse8-cec.c     |   3 +-
>  .../media/usb/rainshadow-cec/rainshadow-cec.c |   3 +-
>  include/drm/drm_dp_helper.h                   |  14 +--
>  include/media/cec-notifier.h                  |  34 ++++--
>  include/media/cec.h                           |  16 ++-
>  include/uapi/linux/cec.h                      |  24 ++++
>  32 files changed, 310 insertions(+), 54 deletions(-)
>  create mode 100644 Documentation/media/uapi/cec/cec-ioc-adap-g-conn-info.rst
> 

I've been doing some testing with my Khadas VIM2 board (amlogic SoC).

It's a bit unusual since it uses the Synopsys bridge, but not the Synopsys
CEC driver (it has its own meson cec driver).

The first thing I noticed is that I did not get any connector info.
I think that the root cause of that is that you forgot that there are
several drm drivers that call cec_notifier_get() instead of cec_notifier_get_conn().

I think all those calls to cec_notifier_get() in drm drivers should be replaced
by cec_notifier_get_conn() where the second argument is NULL, but the third argument
should contain valid connector info.

A quick grep gives me the following drivers that need work:

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
drivers/gpu/drm/exynos/exynos_hdmi.c
drivers/gpu/drm/i2c/tda998x_drv.c
drivers/gpu/drm/sti/sti_hdmi.c
drivers/gpu/drm/tegra/output.c

The second thing I noticed is that patch 2 gave me a new kernel warning, but
I'll do some more testing for that and reply to patch 2/3 once I know more.

Regards,

	Hans