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Thu, 15 Oct 2026 03:28:59 -0700 (PDT) X-Received: by 2002:a17:902:cec2:b0:2dd:c0ff:e72b with SMTP id d9443c01a7336-2e842e02a57mr148391435ad.61.1792060139204; Thu, 15 Oct 2026 03:28:59 -0700 (PDT) Received: from [10.64.69.173] ([114.94.8.21]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2e8422ba80asm80869785ad.63.2026.10.15.03.28.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Oct 2026 03:28:58 -0700 (PDT) Message-ID: Date: Thu, 15 Oct 2026 18:28:52 +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 v7 08/35] drm/msm/dp: add support to send ACT packets for MST 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: <20260929-msm-dp-mst-v7-0-4b81473185e7@oss.qualcomm.com> <20260929-msm-dp-mst-v7-8-4b81473185e7@oss.qualcomm.com> <3c28f89e-8b49-4937-b4c8-66da180a5706@oss.qualcomm.com> Content-Language: en-US From: Yongxing Mou In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: f_6IWLBqevA3XimM7z6DYp38P4m0nAMx X-Authority-Analysis: v=2.4 cv=fNusTpae c=1 sm=1 tr=0 ts=6ad0aaee cx=c_pps a=MTSHoo12Qbhz2p7MsH1ifg==:117 a=Uz3yg00KUFJ2y2WijEJ4bw==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=3WHJM1ZQz_JShphwDgj5:22 a=COk6AnOGAAAA:8 a=EUspDBNiAAAA:8 a=laV4OcfiDC6K5KK7Cz4A:9 a=QEXdDO2ut3YA:10 a=GvdueXVYPmCkWapjIL-Q:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE1MDA0MSBTYWx0ZWRfX1GyCRKoHXMGp iXVy9KUUlkt1fNUk5jCJfLBj77QgqR8aFJBhSF1jF/CXVeqeN3IWqLSNPucyj1njHDMQ48mMnvr RlkaAGhOPumIXrKoKlV4fh2YJMGvngw46hIvcqRy+3MKZhJg5GstdXYu7j60vG0dPmS5pxJtLvi J9RSvOr+5smoTkvXz1tdNEO1DZi+ezdZ3ksj60hsNF1dxpuTqlYkxyri8KFikl/i5nmbvNLmRuN x9diOOaw/clQN3C5jgUvXca2v7xUYy8+VRmf5XZ9jN8dIylni4QY7EjKDIunwpMfr1mclKlSyHc pUGSy/xa+iVtPf3PtQCl/qipjLGiq+kxOmG6LZizlonij7uYaypHXkbosOR0RzZ9Qj+RVBxbETd 7LlLG2cm4gShpzbvDNfOnXD/2qvFUrjUHerjCPuYZqxzIliLcsbluaBCHtQHPpn3EHwcicWM00O geGblVbeZ+wAilGYf/w== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE1MDA0MSBTYWx0ZWRfXya2GMhkx5DOe Q1jV7TJeE87n3HoBZ7MUfBBt5Ss1YeHeDP7hVJ3qHbnGTnJqmRyJ1Mr4z5lvBqTP8PmzwrMbM3+ J3fywU651RQn9d5VYzp+L4uJoYBhFO8= X-Proofpoint-GUID: f_6IWLBqevA3XimM7z6DYp38P4m0nAMx 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=2026-10-14_01,2026-10-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 clxscore=1015 priorityscore=1501 adultscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610150041 On 10/12/2026 8:23 PM, Dmitry Baryshkov wrote: > On Mon, Oct 12, 2026 at 04:44:06PM +0800, Yongxing Mou wrote: >> >> >> On 10/1/2026 6:32 PM, Dmitry Baryshkov wrote: >>> On Tue, Sep 29, 2026 at 12:25:32PM +0800, Yongxing Mou wrote: >>>> From: Abhinav Kumar >>>> >>>> Whenever virtual channel slot allocation changes, the DP >>>> source must send the action control trigger sequence to notify >>>> the sink about the same. This would be applicable during the >>>> start and stop of the pixel stream. Add the infrastructure >>>> to be able to send ACT packets for the DP controller when >>>> operating in MST mode. >>>> >>>> Add REG_DP_MST_ACT, the ACT trigger register used by this sequence. >>>> >>>> Signed-off-by: Abhinav Kumar >>>> Signed-off-by: Yongxing Mou >>>> --- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.c | 44 ++++++++++++++++++++++++++++++++++++- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.h | 5 ++++- >>>> drivers/gpu/drm/msm/dp/dp_display.c | 3 ++- >>>> drivers/gpu/drm/msm/dp/dp_display.h | 1 + >>>> drivers/gpu/drm/msm/dp/dp_reg.h | 1 + >>>> 5 files changed, 51 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> index e1614bc49a7c..65d22505c2b6 100644 >>>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> @@ -142,6 +142,7 @@ struct msm_dp_ctrl_private { >>>> bool core_clks_on; >>>> bool link_clks_on; >>>> bool stream_clks_on[DP_STREAM_MAX]; >>>> + bool mst_active; >>> >>> I really don't like the idea of having this flag in two locations. Here >>> and in the msm_dp_display_private. Can we have it in one place only? >>> >> These two fields are intended to represent different states with different >> lifetimes. >> >> msm_dp::mst_active tracks whether the DP connection has an active MST >> session. The controller field records whether the current controller/link is >> operating in MST mode and remains valid until the link is shut down. >> >> I agree that using mst_active for both fields makes them look like >> duplicated state. I propose renaming the controller field to mst_mode while >> keeping the display-side field as mst_active. >> >> Would you agree with this change? > > What is the difference between these two? I.e. what os the difference > between those two? > The difference between these two states mainly shows up during unplug. mst_active is cleared when dp_display starts handling the unplug, while dp_ctrl needs to keep the MST state until all streams are disabled and the link is shut down. So there is a period during teardown where these two states are different, which is expected. My concern with keeping only one state is that we would need to pass the MST mode through multiple dp_ctrl APIs, which would make the code more complicated. Would it make sense to keep this state in dp_ctrl and rename it to mst_mode to make the distinction clearer? >>>> }; >>> >>> [...] >>> >>>> static void msm_dp_display_unprepare(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 83117e7619f3..472429d09200 100644 >>>> --- a/drivers/gpu/drm/msm/dp/dp_display.h >>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.h >>>> @@ -19,6 +19,7 @@ struct msm_dp { >>>> struct drm_bridge *bridge; >>>> bool audio_enabled; >>>> bool power_on; >>>> + bool mst_active; >>>> unsigned int connector_type; >>>> bool is_edp; >>> >> >