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Message-ID: <ZyPxLpykHkO9Xx_R@ideak-desk.fi.intel.com>
Date: Thu, 31 Oct 2024 23:05:50 +0200
From: Imre Deak <imre.deak@...el.com>
To: Abel Vesa <abel.vesa@...aro.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>,
Danilo Krummrich <dakr@...hat.com>,
Jani Nikula <jani.nikula@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Tvrtko Ursulin <tursulin@...ulin.net>,
Rob Clark <robdclark@...il.com>,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Sean Paul <sean@...rly.run>,
Marijn Suijten <marijn.suijten@...ainline.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konradybcio@...nel.org>,
Johan Hovold <johan@...nel.org>, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, nouveau@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org
Subject: Re: [PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent
mode
On Thu, Oct 31, 2024 at 05:12:45PM +0200, 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.
>
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> ---
> drivers/gpu/drm/display/drm_dp_helper.c | 17 +++++++++++++++++
> include/drm/display/drm_dp_helper.h | 1 +
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> index 6ee51003de3ce616c3a52653c2f1979ad7658e21..38d612345986ad54b42228902ea718a089d169c4 100644
> --- a/drivers/gpu/drm/display/drm_dp_helper.c
> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> @@ -2694,6 +2694,23 @@ int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE])
> }
> EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate);
>
> +/**
> + * drm_dp_lttpr_set_transparent_mode - set the LTTPR in transparent mode
> + * @aux: DisplayPort AUX channel
> + * @enable: Enable or disable transparent mode
> + *
> + * Returns 0 on success or a negative error code on failure.
Should be "Returns 1 on success".
> + */
> +
> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable)
> +{
> + u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
> + DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
> +
> + return drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
> +}
> +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
> +
> /**
> * drm_dp_lttpr_max_lane_count - get the maximum lane count supported by all LTTPRs
> * @caps: LTTPR common capabilities
> diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
> index 279624833ea9259809428162f4e845654359f8c9..8821ab2d36b0e04d38ccbdddcb703b34de7ed680 100644
> --- a/include/drm/display/drm_dp_helper.h
> +++ b/include/drm/display/drm_dp_helper.h
> @@ -625,6 +625,7 @@ int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux,
> u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
> int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);
> int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable);
> int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
> bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
> bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
>
> --
> 2.34.1
>
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