[PATCH v4 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

[Abhinav Kumar]

On 1/8/2025 6:31 AM, Abel Vesa wrote:
> According to the DisplayPort standard, LTTPRs have two operating
> modes:
>   - non-transparent - it replies to DPCD LTTPR field specific AUX
>     requests, while passes through all other AUX requests
>   - transparent - it passes through all AUX requests.
> 
> Switching between this two modes is done by the DPTX by issuing
> an AUX write to the DPCD PHY_REPEATER_MODE register.
> 
> Add a generic helper that allows switching between these modes.
> 
> Also add a generic wrapper for the helper that handles the explicit
> disabling of non-transparent mode and its disable->enable sequence
> mentioned in the DP Standard v2.0 section 3.6.6.1. Do this in order
> to move this handling out of the vendor specific driver implementation
> into the generic framework.
> 
> Tested-by: Johan Hovold <johan+linaro at kernel.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> Reviewed-by: Johan Hovold <johan+linaro at kernel.org>
> Signed-off-by: Abel Vesa <abel.vesa at linaro.org>
> ---
>   drivers/gpu/drm/display/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++
>   include/drm/display/drm_dp_helper.h     |  2 ++
>   2 files changed, 64 insertions(+)
> 

Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>