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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 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 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=Jq/8bc4C 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=_K5XuSEh1TEqbUxoQ0s3:22 a=88Pab4rnIKjo3RbOS5oA:9 a=QEXdDO2ut3YA:10 a=Fk4IpSoW4aLDllm1B1p-:22 X-Proofpoint-ORIG-GUID: TDhYuX1GlxKo5VMtkQykY9_Vb2VDANm5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI0MDAyOCBTYWx0ZWRfX29vMXbkHgPsO ovArbYXvi/z/a+/0f69KglG1889+p6AEqqBfe8Q8JdxCwZwr2cA91747+esfPt1wulTxRoJ95gd /bidp91Y+I0AB2cAg//cxxAWlrdSuSVeC22tmgUHHRS9YyIcK9DDcr6AaxKrVDzJf8dyl0eTRwz 7yc8x9X1oBFU9qowaPzvpK3Iwfomr1Kz1FQWN6Q5Z1xPvzoip3ZfBiZAAYAxrUxCmsmGPJdSlle pOB6Gbm1akjNyePxeSbJdHfAtZVd97FNhNKp7gfmg4cofEeaXURINJxhwYRJSE8kDWADTt5ivXF iN8Ga91l8JfiuFe5nqJWGHuWP+TaFGo/q64LmKD8O6ZF1YuqIOttMBO9othVPGSCKKKe7URLTEi uQ5TK/ppb9j5htsxrEGhlC7YbqGpcb0EY5805XGClVaz7+a+YBQEH0+WsfDIT3t5Y+oj2vAGAdG YQLVC8rucw2vQG1zcOg== X-Proofpoint-GUID: TDhYuX1GlxKo5VMtkQykY9_Vb2VDANm5 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 clxscore=1015 lowpriorityscore=0 malwarescore=0 priorityscore=1501 spamscore=0 adultscore=0 phishscore=0 suspectscore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2602240028 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