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Mon, 03 Feb 2025 02:58:21 -0800 (PST) Received: from [127.0.1.1] ([86.123.96.125]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c5c13a0efsm12555083f8f.60.2025.02.03.02.58.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Feb 2025 02:58:21 -0800 (PST) From: Abel Vesa Date: Mon, 03 Feb 2025 12:57:56 +0200 Subject: [PATCH v5 1/4] drm/dp: Add helper to set LTTPRs in transparent mode MIME-Version: 1.0 Message-Id: <20250203-drm-dp-msm-add-lttpr-transparent-mode-set-v5-1-c865d0e56d6e@linaro.org> References: <20250203-drm-dp-msm-add-lttpr-transparent-mode-set-v5-0-c865d0e56d6e@linaro.org> In-Reply-To: <20250203-drm-dp-msm-add-lttpr-transparent-mode-set-v5-0-c865d0e56d6e@linaro.org> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Karol Herbst , Lyude Paul , Danilo Krummrich , Jani Nikula , Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , Rob Clark , Abhinav Kumar , Dmitry Baryshkov , Sean Paul , Marijn Suijten Cc: Bjorn Andersson , Konrad Dybcio , Johan Hovold , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Abel Vesa , Johan Hovold X-Mailer: b4 0.15-dev-dedf8 X-Developer-Signature: v=1; a=openpgp-sha256; l=4430; i=abel.vesa@linaro.org; h=from:subject:message-id; bh=GWDPLjsD/LaP+fD+1LfYD/7l93rcVcvESuGQSIuupYA=; b=owEBbQKS/ZANAwAKARtfRMkAlRVWAcsmYgBnoKFE89QOXDiWSJro65eII8Rv3UxY8Qc4UyUUI 531ArtGoZaJAjMEAAEKAB0WIQRO8+4RTnqPKsqn0bgbX0TJAJUVVgUCZ6ChRAAKCRAbX0TJAJUV VgtjD/43YCJn+kR3wQvW34kEv7ddETk/bpBbvc+gF6M7mOlHTfHynaAffq939L1AgY2sKs0Ehem W3Ql9tbPbR5GPSxwLs+TK6wRt6Gqia8dwDdS+GRPBl8JtMFEI3Hf1Rzs9akUdToFV5BFIaqm1a+ zZgwAdSycOWeyoVwotoojTFVBH5l9iHVl7xJkcCIMYP+LRke8XLepAW23jcYrjpo0Af3uk2UxZv PNigdxWHhIMyubZI1QzE8RoaJFLVEvwiIymaaICaU51PXN4p+651Jgyz5v2Wd/zWAelnH89HFV3 jhVfTpHgVEx/2ELpV2HjnWApWKO2y3UxalTfbG4z4twC6sR8bj4zoR3e6A4H+tp3ZM/IL++quo6 toJJwamCFUy0XUFSQm7HY4z1jVrWNvtns4yBm6c+iAXAIIKtoDfgI/XWCrEo514Qyeoba45IovW VfyWGZpYEEIKw1TOCGMMdEqUCikLbg9UtID5UCtqGU4oQelo06HWIJCYrvH3cblppwNc5gRacyb v2MIbm8qQ4wPv8iltN0OK+XRbanbtcC9N5PbB5x+eX3pswEUz51It3L3cSRY1HGLKuB3w0vDchB Kt6XEsCoDVip8OJAOhfAc79z2yz0Xvjz1chZCqg/vNqm06bjUOuQWUYVQRlEh+hX7WVf/Grria5 86nPpHdX0g3xNrQ== X-Developer-Key: i=abel.vesa@linaro.org; a=openpgp; fpr=6AFF162D57F4223A8770EF5AF7BF214136F41FAE X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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 Reviewed-by: Dmitry Baryshkov Reviewed-by: Johan Hovold Reviewed-by: Abhinav Kumar Signed-off-by: Abel Vesa --- drivers/gpu/drm/display/drm_dp_helper.c | 61 +++++++++++++++++++++++++++++++++ include/drm/display/drm_dp_helper.h | 2 ++ 2 files changed, 63 insertions(+) diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index da3c8521a7fa7d3c9761377363cdd4b44ab1106e..ea3ad0fe51c4ce13961f2918cd651ab2d23b4edd 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -2817,6 +2817,67 @@ 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. + */ +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; + int ret = drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val); + + if (ret < 0) + return ret; + + return (ret == 1) ? 0 : -EIO; +} +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode); + +/** + * drm_dp_lttpr_init() - init LTTPR transparency mode according to DP standard + * @aux: DisplayPort AUX channel + * @lttpr_count: Number of LTTPRs. Between 0 and 8, according to DP standard. + * Negative error code for any non-valid number. + * See drm_dp_lttpr_count(). + * + * Returns: 0 on success or a negative error code on failure. + */ +int drm_dp_lttpr_init(struct drm_dp_aux *aux, int lttpr_count) +{ + int ret; + + if (!lttpr_count) + return 0; + + /* + * See DP Standard v2.0 3.6.6.1 about the explicit disabling of + * non-transparent mode and the disable->enable non-transparent mode + * sequence. + */ + ret = drm_dp_lttpr_set_transparent_mode(aux, true); + if (ret) + return ret; + + if (lttpr_count < 0) + return -ENODEV; + + if (drm_dp_lttpr_set_transparent_mode(aux, false)) { + /* + * Roll-back to transparent mode if setting non-transparent + * mode has failed + */ + drm_dp_lttpr_set_transparent_mode(aux, true); + return -EINVAL; + } + + return 0; +} +EXPORT_SYMBOL(drm_dp_lttpr_init); + /** * 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 8f4054a560396a43750570a8c2e95624039ab8ad..3311df3b58255cf0620391d0948ccf6b569a8a34 100644 --- a/include/drm/display/drm_dp_helper.h +++ b/include/drm/display/drm_dp_helper.h @@ -630,6 +630,8 @@ 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_init(struct drm_dp_aux *aux, int lttpr_count); 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]);