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[78.88.45.245]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-66003d5ca55sm1989820a12.28.2026.03.02.04.37.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Mar 2026 04:37:45 -0800 (PST) Message-ID: <00ed5c99-d844-4fcf-b4f9-e883938f46fe@oss.qualcomm.com> Date: Mon, 2 Mar 2026 13:37:42 +0100 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 0/7] drm/msm/dpu: simplify VBIF handling To: Dmitry Baryshkov Cc: Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Sean Paul , Marijn Suijten , David Airlie , Simona Vetter , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20260227-drop-vbif-nrt-v1-0-2b97d0438182@oss.qualcomm.com> <385d044c-29ef-44c2-9faa-0c306af44772@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: CjX5rtXTXVYNos6C4C0HjX7-gKwzgAaL X-Proofpoint-GUID: CjX5rtXTXVYNos6C4C0HjX7-gKwzgAaL X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzAyMDEwNiBTYWx0ZWRfX2obb3/KygKEp MNRABX1h9VemTKhfG/Dj2LtTKDZ6W0S10YzPvhnYQM9QSl3ryZOBwfVCmLEfJ2YYW0xiAy28K8T U3Had+0MPMxoVwWrgAaJRtSR2GnUNhCZ6GsXFm7L1CgSKhTX1ndXn8Z+f96pQ7kPI90hJZ3/nBV 5jrIfkxSupFwFrPNw+vpqgmrAPS0uJNoD7oTaDcNsUOr39B43Hxp7nGpV498F8348mb75DD8VJ6 a0wQMIOfrWzFK9l52edMJz9WAQ5cHUKIi47hCvOprp2cgg9bvwAqCGtDZBpcDoNkh935xDDpp/9 tCztr6KTanKQePbgtki1TvNdUj8qGW7om/TTLb03EiMSCaN4+dtgEMJkDfsll5Qw36g4OVYsZss z+cj4HiHfO9P6x3qpL3Ap4eD8tR/E+FiUTmCtzKfWYwg0Lu6AB0oMkRR6isd2HmdnVx43LhYRY7 MggGsmx/w4pYIb2BawQ== X-Authority-Analysis: v=2.4 cv=cLntc1eN c=1 sm=1 tr=0 ts=69a5849b cx=c_pps a=qKBjSQ1v91RyAK45QCPf5w==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=M2fHq20qpG9OoBxEoUIA:9 a=QEXdDO2ut3YA:10 a=NFOGd7dJGGMPyQGDc5-O:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-02_03,2026-02-27_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 malwarescore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603020106 On 3/2/26 1:33 PM, Dmitry Baryshkov wrote: > On Mon, Mar 02, 2026 at 12:58:42PM +0100, Konrad Dybcio wrote: >> On 2/27/26 7:36 PM, Dmitry Baryshkov wrote: >>> Once Konrad asked, what is the use for VBIF_NRT. Answering to his >>> question revealed that it's not actually used by the DPU driver. >>> >>> There are two VBIF interfaces two memory, VBIF_RT and VBIF_NRT with >>> VBIF_NRT being used only for the offscreen rotator, a separate block >>> performing writeback operation with the optional 90 degree rotation. >>> This block will require a separate isntance of the DPU driver, and it is >>> not supported at this point. >> >> (in case someone interested is reading this - patches welcome!) >> >>> The only exception to that rule is MSM8996, where VBIF_NRT has also been >>> used for outputting all writeback data. The DPU driver don't support WB >>> on that platform and most likely will not in the close feature. >> >> Unfortunately, it seems that way. Fortunately, it seems like it's indeed >> isolated to MSM8996. >> >> This patchset is tearing out a lot of abstraction (which would only be >> useful for that SoC though) - if someone decides to work on it, do you >> think this should be effectively reverted, or should the NRT VBIF be >> instantiated in some other, more locallized way? > > I think it should be added as a separate vbif_nrt, added and handled > without touching the main catalog. The main difference point, xin_id, is > still in place, it will be easy to add dpu_kms->vbif_nrt as a > first-class object (instead of forcing the complexity of > vbif[VBIF_MAX]). In such a case I'd prefer if calling code passes VBIF > directly to dpu_vbif_set_*() functions instead of passing the index (or > it might be easier to have a separate wrapper around those functions). > > My opinion is that if something isn't applicable to 99% of cases, those > 99% should not care about the remaining 1% usecase. Sure, that makes sense. I wanted to make sure your opinion is put in writing for the aforementioned "someone comes around to hack on this" case Konrad