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Wed, 26 Aug 2026 06:07:10 -0700 (PDT) X-Received: by 2002:a05:6a00:c96:b0:845:ce5f:c926 with SMTP id d2e1a72fcca58-85372ea6666mr12572918b3a.1.1787749630363; Wed, 26 Aug 2026 06:07:10 -0700 (PDT) Received: from [10.219.57.226] ([202.46.23.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-85359cdfeebsm917003b3a.4.2026.08.26.06.07.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Aug 2026 06:07:09 -0700 (PDT) Message-ID: <23e31249-cce2-421e-88f7-1a2af66e34b6@oss.qualcomm.com> Date: Wed, 26 Aug 2026 18:37:00 +0530 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/15] accel/qda: Qualcomm DSP Accelerator driver To: rob.clark@oss.qualcomm.com, Krzysztof Kozlowski Cc: Oded Gabbay , Jonathan Corbet , Shuah Khan , Randy Dunlap , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Bharath Kumar , Chenna Kesava Raju , srinivas.kandagatla@oss.qualcomm.com, dmitry.baryshkov@oss.qualcomm.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-arm-msm@vger.kernel.org, llvm@lists.linux.dev, iommu@lists.linux.dev, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Anandu Krishnan E References: <20260817-qda-v2-v2-0-69a02e9090d4@oss.qualcomm.com> <3322b42b-3755-45ec-ad55-345125f0d488@kernel.org> <10349e29-b583-403f-a89a-9a00c73666bc@oss.qualcomm.com> <87dca76c-851e-4cc3-ab91-68949d283b79@kernel.org> <318f14c2-0e87-4e07-8173-1511dca67d78@kernel.org> Content-Language: en-US From: Ekansh Gupta In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=fPEJG5ae c=1 sm=1 tr=0 ts=6a8ee4ff cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=j4ogTh8yFefVWWEFDRgCtg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yOCtJkima9RkubShWh1s:22 a=VwQbUJbxAAAA:8 a=HVFQHpX-XFYh-alqn_4A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=zc0IvFSfCIW2DFIPzwfm:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI2MDEwOCBTYWx0ZWRfX+y9UeMh6uB8d L34K1QFV7FXfb3U3TaxD4qqkVhfxXHNncSlCfsX97muKWGhAO4P3/RSzuQOMspZErx20NMYXtYC MVwIDeNo/Zn4ytWb5Yjfin23tdxeZKM= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI2MDEwOCBTYWx0ZWRfX8Qo/zs9I1EQt z0JCxp26xZGcOttgTTVsq+e12RFEH8Mg85ssN2TYfBqVWzvc0c3ScWkamPT128Wl9/Qxb2uubtX rfQRbDnw58G/0GpuMPb4j8ZAWgA3m1PxDVzwmw27917xRzPemstjMvYkfPaiXiuMClnbwatvQ/K Y9KVR2akMWQAPjfLowm4dX1DpvQwYQkBAvJHOqirvCBlQo73RdTuLDaWZTHZnrYC5TUQfeYTF0n +19YDaZwwfPExD16thKuQgIWiaJ5wTaM5XKDMZYxgG1fjL5l/FBYlU51+7kwnhquJbmfkxb0mgl 6OcmlJBGZYECZxmYDRO/mirTFoc+MaEGAFUJUrDSvPnuwun+gyvJ01qsaWfEVy+Xa9VuswDqvbr HHkXnrbup/ow65olRBHZ2C8vgMdnnvk/w1LQwqjrfku21aQbOuAddwWJY7ULtidJhv5C7++bbIv XK/VN0jJg8DeFu6E6rQ== X-Proofpoint-ORIG-GUID: f7_iHl-90hmaO2NzcCDDXMT6MgSvQ3_y X-Proofpoint-GUID: f7_iHl-90hmaO2NzcCDDXMT6MgSvQ3_y 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_03,2026-08-26_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 suspectscore=0 impostorscore=0 malwarescore=0 clxscore=1015 adultscore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608260108 On 20-08-2026 20:17, Rob Clark wrote: > On Wed, Aug 19, 2026 at 11:15 PM Krzysztof Kozlowski wrote: >> >> On 19/08/2026 17:48, Rob Clark wrote: >>> On Wed, Aug 19, 2026 at 8:27 AM Krzysztof Kozlowski wrote: >>>> The rule of usptream development is that we do not accept duplicated >>>> code, just because a vendor wants to write something new. This is >>>> basically the concept applied all over the drivers tree, where we pushed >>>> back against all sorts of duplications all over the vendors. >>>> >>>> What I miss in this thread is why would there be any exception here. We >>>> do not grant exceptions from standard practices on "I want" reasons. >>> >>> I agree that we should not have duplicated drivers just for vendor >>> lolz. But when it comes to adopting common frameworks and integrating >>> better into the ecosystem, this doesn't seem like something we should >>> actively discourage. I don't think this is a case of vendor lolz, but >> >> No one discourages it. Following standard Linux kernel practices and >> requirements is not discouraging, do not twist the narrative here. >> Again, it is standard upstream review telling that we do not duplicate >> drivers. Ever, unless there is serious exception needed. > > I wasn't trying to twist the narrative, just trying to come up with a > path forward that isn't "no" or "improve existing driver", since > neither of those gets us towards a future using common frameworks. > >> I asked why there should be an exception granted? Is the reason for >> exception following: >> "We want to adopt common framework" >> ? > > Possibly? But I don't think we want two drivers to be any sort of > long term solution. (Ie. as long as venus/iris have co-exist.) > >> >>> rather reacting to drm/accel emerging as the standard framework for >>> this sort of driver. >>> >>> So how do we get from here to there? >> >> What is wrong with my proposal? > > Maybe I missed something, my understanding was your proposal was > "Grow/replace/improve existing driver instead of coming with a > duplicate".. grow or improve doesn't move us toward common > frameworks. Maybe "replace" is a valid option. If there is something > I missed, then I apologize. > > Options I can think of are: > > 1. Hardware cutoff.. new hw gets new driver, existing hw gets existing > driver > 2. Backwards compat chardev registered by new driver, providing existing > UABI. I'm not 100% sure about the feasibility/drawbacks of this.. > AFAIU the fastrpc folks where planning a backwards compat layer in > userspace, so maybe it is possible. > 3. exception? > > I'd like to know what the feasibility of #2 is, since at a high level > that sounds like the best option. Possibly limit exposure of legacy > UABI to existing hw so we don't get into a place of needing to extend > the legacy UABI for new hw? > > But #1 sounds like a non-controversial place to start regardless. > Possibly with #2 coming as followup and necessary step before eventual > migration to new driver for existing hw? > > Even if we start with #2, how do we handle first-merge-window > bugs/regressions without reverting addition of new driver and removal > of old? It seems like we'd need a window of a couple release cycles > where both drivers exist? > > Maybe others have other/better options in mind? To all, I'm seeking on the approach I should follow to go ahead here. I can work on implementing #1(as per Rob's list) with hw specific compatible for v4 if it's acceptable. #2(compat driver) is something that we are still exploring as we couldn't find any standard way to achieve it. We might start a separate discussion for that once we have few possible designs with us. Happy to take any other suggestion also.> > BR, > -R