[PATCH v2 3/3] drm/bridge: sii9234: use extcon cable detection logic to detect MHL

[Dmitry Baryshkov]

On Thu, Jul 24, 2025 at 08:50:53PM +0200, Henrik Grimler wrote:
> To use MHL we currently need the MHL chip to be permanently on, which
> consumes unnecessary power. Let's use extcon attached to MUIC to enable
> the MHL chip only if it detects an MHL cable.

Does HPD GPIO reflect the correct state of the cable? What is the order
of events in such a case? Should the sii9234 signal to Exynos HDMI that
the link is established?

> 
> Signed-off-by: Henrik Grimler <henrik at grimler.se>
> ---
> v2: add dependency on extcon. Issue reported by kernel test robot
>     <lkp at intel.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig   |  1 +
>  drivers/gpu/drm/bridge/sii9234.c | 89 ++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 87 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index b9e0ca85226a603a24f90c6879d1499f824060cb..f18a083f6e1c6fe40bde5e65a1548acc61a162ae 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -303,6 +303,7 @@ config DRM_SII902X
>  config DRM_SII9234
>  	tristate "Silicon Image SII9234 HDMI/MHL bridge"
>  	depends on OF
> +	select EXTCON

Either this or 'depends on EXTCON || !EXTCON'

>  	help
>  	  Say Y here if you want support for the MHL interface.
>  	  It is an I2C driver, that detects connection of MHL bridge

-- 
With best wishes
Dmitry