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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8434ad03fdcsm12300594b3a.24.2026.06.16.02.36.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Jun 2026 02:36:51 -0700 (PDT) Message-ID: <8681a6e0-fa32-46c9-b28a-e5d569a87247@oss.qualcomm.com> Date: Tue, 16 Jun 2026 17:36:45 +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 v4 18/39] 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: <20260410-msm-dp-mst-v4-0-b20518dea8de@oss.qualcomm.com> <20260410-msm-dp-mst-v4-18-b20518dea8de@oss.qualcomm.com> <6jkqen322yklhb4zzoj2kcgwayhcqm3mhnbrkgimr7zubwewao@gmuopu6uxakq> <49131a73-f60e-4296-a6d4-5ff59331a9dd@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: 8bit X-Authority-Analysis: v=2.4 cv=I/ZVgtgg c=1 sm=1 tr=0 ts=6a311935 cx=c_pps a=rEQLjTOiSrHUhVqRoksmgQ==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=3WHJM1ZQz_JShphwDgj5:22 a=COk6AnOGAAAA:8 a=EUspDBNiAAAA:8 a=hoFbmsMDQYFultheuLUA:9 a=+jEqtf1s3R9VXZ0wqowq2kgwd+I=:19 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=2VI0MkxyNR6bbpdq8BZq:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNjE2MDA5NiBTYWx0ZWRfX7PqQ/K/G1WNR gKPrdfYuVuqfi/IXtTUQixmW2pxvf8Ftjv+zieDKpv36acpMmR3FyKDdgQmODcrDACjjhOuyrDi wOixz16LzbSzABqImGU6tlKOLyb/SZ4= X-Proofpoint-ORIG-GUID: IUxe80LC_CzEcBKB8mUq8XDMAOZlGtX5 X-Proofpoint-GUID: IUxe80LC_CzEcBKB8mUq8XDMAOZlGtX5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjE2MDA5NiBTYWx0ZWRfX8Zj2pXjDVU5F wGdQ7gRcf7wQGbv9WYkfc/kkMZnpAYoT4oZHMGJ0RG/0uLMqUIcgQsNUmd0lih6ZK0xb44a9VdX MQTf+pWuAJorAoVuSnSZ1GrzHWP1Y6zRkW2DxHibz4q67y4i4Ss08oDpzazQn1qn8LbaHJo71jM tvly7LA8pCLxxiXqOs5nJNIQsVztWQJADIcL2lzd+mdIVKJEpgzjhGgAeouu4cky10KsbYsEpRN QW2F1wEuDO1YvUwGKZDXcGkAAZMcp+AzOxeTEOfmGdt00acKzQzFf7+RN8fpJ6EAheaLqBRC2wJ 6Vm+6SBu5KPpgCLzA7Z8ifVr1ntzcBz6MXPfrFE/HUteMmRmjMt+rr2/9nHbEtWhHW1ia1alPXy Ak6vfunlq9WsVSYbCVIA7EhYEFOU0u6ZOompG8Tp4zBiEI1pO5cYOaPt/xy88ZQb5szqOvp7vun Erq92IqD+llWD7OShsQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-16_02,2026-06-15_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 adultscore=0 malwarescore=0 spamscore=0 clxscore=1015 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606040000 definitions=main-2606160096 On 6/16/2026 8:41 AM, Dmitry Baryshkov wrote: > On Mon, Jun 15, 2026 at 04:21:14PM +0800, Yongxing Mou wrote: >> >> >> On 4/12/2026 2:57 AM, Dmitry Baryshkov wrote: >>> On Fri, Apr 10, 2026 at 05:33:53PM +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. >>>> >>>> Signed-off-by: Abhinav Kumar >>>> Signed-off-by: Yongxing Mou >>>> --- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.c | 43 +++++++++++++++++++++++++++++++++++-- >>>> drivers/gpu/drm/msm/dp/dp_ctrl.h | 3 ++- >>>> 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 | 2 ++ >>>> 5 files changed, 48 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> index 1109b2df21be..6f25145ef214 100644 >>>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c >>>> @@ -143,6 +143,7 @@ struct msm_dp_ctrl_private { >>>> bool core_clks_on; >>>> bool link_clks_on; >>>> bool stream_clks_on[DP_STREAM_MAX]; >>>> + bool mst_active; >>>> }; >>>> static inline u32 msm_dp_read_ahb(const struct msm_dp_ctrl_private *ctrl, u32 offset) >>>> @@ -228,6 +229,32 @@ static int msm_dp_aux_link_configure(struct drm_dp_aux *aux, >>>> return err; >>>> } >>>> +int msm_dp_ctrl_mst_send_act(struct msm_dp_ctrl *msm_dp_ctrl) >>>> +{ >>>> + struct msm_dp_ctrl_private *ctrl; >>>> + bool act_complete; >>>> + >>>> + ctrl = container_of(msm_dp_ctrl, struct msm_dp_ctrl_private, msm_dp_ctrl); >>>> + >>>> + if (!ctrl->mst_active) >>>> + return 0; >>>> + >>>> + msm_dp_write_link(ctrl, 0, REG_DP_MST_ACT, 0x1); >>>> + /* make sure ACT signal is performed */ >>>> + wmb(); >>>> + >>>> + msleep(20); /* needs 1 frame time */ >>> >>> 20 ms is 50fps. What if we have 30 or 25 fps? >>> >> This hasn’t been considered yet. Do we need to change this to wait based on >> the per-frame duration of the mode? > > I don't know. You wrote that we wait for 1 frame here. Why? > The one-frame delay here is inherited from the downstream code. IPCAT describes it as: ‘When written to 1, a sequence of 4 ACT headers will be sent at the earliest possible time. The field will be cleared by HW after the 4 ACTs are sent, which then triggers the READY_FOR_VIDEO interrupt.’ So to cover the worst-case scenario, we chose one frame. Please correct me if i'm wrong. >