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Mon, 23 Feb 2026 19:33:14 -0800 (PST) X-Received: by 2002:a05:7022:4387:b0:121:9f05:c4c2 with SMTP id a92af1059eb24-1276ad18ec5mr3365882c88.23.1771903993530; Mon, 23 Feb 2026 19:33:13 -0800 (PST) Received: from [192.168.86.165] ([76.176.48.107]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1276af20fc8sm10325680c88.6.2026.02.23.19.33.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Feb 2026 19:33:12 -0800 (PST) Message-ID: Date: Mon, 23 Feb 2026 19:33:10 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 01/18] accel/qda: Add Qualcomm QDA DSP accelerator driver docs To: Ekansh Gupta , Oded Gabbay , Jonathan Corbet , Shuah Khan , Joerg Roedel , Will Deacon , Robin Murphy , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= Cc: dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, iommu@lists.linux.dev, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Srinivas Kandagatla , Dmitry Baryshkov , Bharath Kumar , Chenna Kesava Raju References: <20260224-qda-firstpost-v1-0-fe46a9c1a046@oss.qualcomm.com> <20260224-qda-firstpost-v1-1-fe46a9c1a046@oss.qualcomm.com> Content-Language: en-US From: Trilok Soni In-Reply-To: <20260224-qda-firstpost-v1-1-fe46a9c1a046@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=X7Jf6WTe c=1 sm=1 tr=0 ts=699d1bfa cx=c_pps a=JYo30EpNSr/tUYqK9jHPoA==:117 a=lsoD3MMNObdLvy1227ExmA==:17 a=IkcTkHD0fZMA:10 a=HzLeVaNsDn8A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=88Pab4rnIKjo3RbOS5oA:9 a=QEXdDO2ut3YA:10 a=Fk4IpSoW4aLDllm1B1p-:22 X-Proofpoint-ORIG-GUID: zNwcK5uhySN2A4xf5mw1Ezzq-5bHFbgw X-Proofpoint-GUID: zNwcK5uhySN2A4xf5mw1Ezzq-5bHFbgw X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI0MDAyOCBTYWx0ZWRfXwqlF15G/b2Z7 AMWWbKiTSYm5p+1eetwlXJmOf6joa7YGk3qJWEMcl0uac8DiUd+0T48qm1YH/Eo1sPLKaU60nY8 ZHZC1CrVG4TsQ2CDuJ/wxntOPdrxp/iHn88jq6pdlO6m7nW1IsSPSyTC6O9nChX6z9fPevufOyY bSrxKBUucxBl+MBubq3zrLmt8Dfyyj3kxmDZ3vDm6PNto5sYpu0ogn1SaljT5OK0yOxX16nvthn HxOMDEWgNQr7TkfsV92cf7LBEIFJyKOTA132WJDmOTUF9dmAVgCBxD1YHuxJtxqT7JqJmQggaHP 0b57WTPfPysEaq6gGdYhWUb+Rh7912bs3PZulDLPSlNuMh1u1wC2if6m2HELFblygEP3s2LCpkY aeSGyprap+ntbVFfJxSurDkuJPbGZmI2PxMQ7det7AZpoC+Wz868LtNrsFiwVCFVM5r3NVRitqX nEI1OBnFvFd0Q5J/3Fg== 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=2026-02-23_06,2026-02-23_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 priorityscore=1501 clxscore=1011 bulkscore=0 adultscore=0 spamscore=0 impostorscore=0 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2602240028 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 2/23/2026 11:08 AM, Ekansh Gupta wrote: > Add initial documentation for the Qualcomm DSP Accelerator (QDA) driver > integrated in the DRM accel subsystem. > > The new docs introduce QDA as a DRM/accel-based implementation of > Hexagon DSP offload that is intended as a modern alternative to the > legacy FastRPC driver in drivers/misc. The text describes the driver > motivation, high-level architecture and interaction with IOMMU context > banks, GEM-based buffer management and the RPMsg transport. > > The user-space facing section documents the main QDA IOCTLs used to > establish DSP sessions, manage GEM buffer objects and invoke remote > procedures using the FastRPC protocol, along with a typical lifecycle > example for applications. > > Finally, the driver is wired into the Compute Accelerators > documentation index under Documentation/accel, and a brief debugging > section shows how to enable dynamic debug for the QDA implementation. So existing applications written over character device UAPI needs to be rewritten over new UAPI and it will be broken once this driver gets merged? Are we going to keep both the drivers in the Linux kernel and not deprecate the /char device one? Is Qualcomm going to provide the wrapper library in the userspace so that existing applications by our customers and developers keep working w/ the newer kernel if the char interface based driver gets deprecated? It is not clear from your text above. ---Trilok Soni