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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-arm-msm@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-GUID: aTSL5333EfTQr5L8LQuTKi9dBAYkWeIo X-Proofpoint-ORIG-GUID: aTSL5333EfTQr5L8LQuTKi9dBAYkWeIo X-Authority-Analysis: v=2.4 cv=Hpp72kTS c=1 sm=1 tr=0 ts=69a5849b cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=M2fHq20qpG9OoBxEoUIA:9 a=QEXdDO2ut3YA:10 a=bTQJ7kPSJx9SKPbeHEYW:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzAyMDEwNiBTYWx0ZWRfX0C2DoRTqwS3R bTaCgSSHN7F9ZU8lReZ7kcaeGEkIryF4/4UWgGc2jVzJB8lXtN8C9uBYsfg/H5VVVzAfXYSF6Bh k2t9O9mKjwg6TciewPc76KHoJ13kCTwopRlAR3TC1qrXgdoanGf55OMEafCzdGvSVZx45u1xl8u UpVfDWLQsrWdz4oGUNiu36KQjmwXy6LLO2jrmXk9gMjlL4sWvM736CbTgUD8YNW3i+HWiWVBaNy TItauQD/L2csSUi0jv14j7aOev4ItiXCr3bbtYv4OHqRX/oGIijT7nwKerj94m3m3/C+tCkhGyN f0oDvbSi+nqDeGSEgEzngDsHLlpSAA3D/LrR9XIdQRRrXOQqHKm5i3PErV3gsB9MIF0fM6eFMn5 ShzJPuYLrVu/hgFezlKZWukisubSGHll+IOE5v0keMNL2E2sof1nUqNJFSrZP9UqngxB37fNAuM A7ByEaU4l/XCaS5edqw== 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 lowpriorityscore=0 suspectscore=0 impostorscore=0 phishscore=0 priorityscore=1501 adultscore=0 bulkscore=0 malwarescore=0 clxscore=1015 spamscore=0 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