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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8535cd8a41esm588474b3a.29.2026.08.26.00.49.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Aug 2026 00:49:12 -0700 (PDT) Message-ID: <4b15dc5d-d9ff-45b9-b46e-e36319ff0570@oss.qualcomm.com> Date: Wed, 26 Aug 2026 15:49:06 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RESEND v5 17/25] drm/msm/dp: add link_ready to manage link-level operations To: Dmitry Baryshkov Cc: Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Sean Paul , Marijn Suijten , David Airlie , Simona Vetter , Jessica Zhang , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org, Abhinav Kumar References: <20260629-msm-dp-mst-v5-0-2ed6aee1867a@oss.qualcomm.com> <20260629-msm-dp-mst-v5-17-2ed6aee1867a@oss.qualcomm.com> <2ciespht5pfxvqnrik4a26drkmow2ilvxbkcnpt43jprhndryq@vfetl33dz3yg> Content-Language: en-US From: Yongxing Mou In-Reply-To: <2ciespht5pfxvqnrik4a26drkmow2ilvxbkcnpt43jprhndryq@vfetl33dz3yg> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: _2-Wd6xrERkvnu5oLOj4lu7e4m9bhACK X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI2MDA2MyBTYWx0ZWRfX8m7ybub/sryo QgIinBaFex/ID9UzVtbnH26whrPBXFilAVqNHJEQz6oCbfNs4055wvgwLBHZGVN90+BhNeEkN0D T1IOJQEAATOkxx4L6x446qIhvbXdn+kZbBTG+gwcdFyJl8c8rhkZSxVr3MTwNHHUXv7GaEWSRW9 wg/KrD4LCCl65z3HUoIZL0ep0gSVjSd0YZT7rjdsvFZ9jYFQcdo/eD2b5EfAzHvxJNhcK6rik/3 6a3Bvg5heed+FSFqZEevUt4q+mCc4Wm1ZxdpeKztdhCzz1eEUwxK1PAvSJHJy0CHJZRjrqN+LX8 ZGkA1vJgovN7wBgES4Z1/Ayj29D6MpnhGV5KQ7ZzpcUjD1S03gPCA33kSLNWpaj6XDZ9l7Jr+/n oCpp4U97O0/mF0X/B2u72PpJntejtqlfGYCM1LKldTVSavFh0mlpZm+bDByIffInB8NhHfz6NCM VnWPIq9IdxFf0tMWwlg== X-Authority-Analysis: v=2.4 cv=d8LFDxjE c=1 sm=1 tr=0 ts=6a8e9a7a cx=c_pps a=rEQLjTOiSrHUhVqRoksmgQ==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=COk6AnOGAAAA:8 a=EUspDBNiAAAA:8 a=e8pokjpGc4Y85sSXAHsA:9 a=QEXdDO2ut3YA:10 a=2VI0MkxyNR6bbpdq8BZq:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-ORIG-GUID: _2-Wd6xrERkvnu5oLOj4lu7e4m9bhACK X-Proofpoint-Spam-Info: AW1haW4tMjYwODI2MDA2MyBTYWx0ZWRfX6bmGAEEGc4XQ 4TKCnM3ibEi1mmjxNNFbiY6V1t82LUFcYgivx6BNWbKXnKldoHQK7bPzw6TUUjl2uN2WIx/S/ZT 0BH1Xbq1b/ZGELJUuyunn9snQNsnPsY= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-26_02,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 malwarescore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 adultscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608260063 On 7/13/2026 7:46 AM, Dmitry Baryshkov wrote: > On Mon, Jun 29, 2026 at 10:14:38PM +0800, Yongxing Mou wrote: >> In MST mode, multiple streams share the same DP link. Track a link_ready >> state so msm_dp_display_prepare_link() runs only once per link and >> repeated calls are skipped. >> >> Signed-off-by: Abhinav Kumar >> Signed-off-by: Yongxing Mou >> --- >> drivers/gpu/drm/msm/dp/dp_display.c | 42 ++++++++++++++++++++++++------------- >> drivers/gpu/drm/msm/dp/dp_display.h | 1 + >> 2 files changed, 29 insertions(+), 14 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c >> index 2a74302bcb7c..d56ee10ee065 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.c >> +++ b/drivers/gpu/drm/msm/dp/dp_display.c >> @@ -702,6 +702,9 @@ int msm_dp_display_prepare_link(struct msm_dp *msm_dp_display) >> if (msm_dp_display->is_edp) >> msm_dp_hpd_plug_handle(dp); >> >> + if (msm_dp_display->link_ready) >> + return 0; >> + > > What kind of locking is protecting this variable? What prevents it from > being accessed concurrently? > In MST, the entire function is protected by mst_lock, so concurrent access to this variable is serialized. >> rc = pm_runtime_resume_and_get(&msm_dp_display->pdev->dev); >> if (rc) { >> DRM_ERROR("failed to pm_runtime_resume\n"); >> @@ -714,14 +717,18 @@ int msm_dp_display_prepare_link(struct msm_dp *msm_dp_display) >> if (!msm_dp_display->active_stream_cnt) { >> msm_dp_display_host_phy_init(dp); >> force_link_train = true; >> + >> + rc = msm_dp_ctrl_on_link(dp->ctrl, dp->panel); >> + if (rc) >> + DRM_ERROR("Failed link training (rc=%d)\n", rc); >> + // TODO: schedule drm_connector_set_link_status_property() >> } >> >> - rc = msm_dp_ctrl_on_link(dp->ctrl, dp->panel); >> - if (rc) >> - DRM_ERROR("Failed link training (rc=%d)\n", rc); >> - // TODO: schedule drm_connector_set_link_status_property() > > Why is it being moved now rather than in the patch where > active_stream_cnt was introduced? > Got it. will move to that part >> + rc = msm_dp_ctrl_prepare_stream_on(dp->ctrl, dp->panel, force_link_train); >> + if (!rc) >> + msm_dp_display->link_ready = true; >> >> - return msm_dp_ctrl_prepare_stream_on(dp->ctrl, dp->panel, force_link_train); >> + return rc; >> } >> >> static int msm_dp_display_enable(struct msm_dp_display_private *dp, > >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h >> index 676213a48089..0464f8941e8d 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.h >> +++ b/drivers/gpu/drm/msm/dp/dp_display.h >> @@ -22,6 +22,7 @@ struct msm_dp { >> bool mst_active; >> unsigned int connector_type; >> bool is_edp; >> + bool link_ready; > > Please group the status variables together. > Got it. >> >> struct msm_dp_audio *msm_dp_audio; >> bool psr_supported; >> >> -- >> 2.43.0 >> >