From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 051D73ACF18; Wed, 19 Aug 2026 14:53:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787151208; cv=none; b=o/WaRn7u8OZwr4cPcm3vnis6MF0N79TDPka1I94AiorRAzo8HEkc75EfrlCjiKtAEfQq3hiVntQbcBzWZRZ44f9E1qbaP1t2FHGsq+eSdZ8trVZSoMDj/xGV2mmUF4STZCb1EREX2MlEfiriQR300vCjzrkzkQPUIza6fN4JAnI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787151208; c=relaxed/simple; bh=QVcVWBaHPP43ECVAhtIVq7+L2mpEbVXEeS+wYVsb4A4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uITbxNY+mMaEBcvg9toq8bhs0cPtZp/tfJUgD7Mo0FRzrXm1KUr1YlOsly2pZQK1KFrkv6rVuR5r4FUFYGeCXH6fU6q8bgGw0C7xJk8a5kCQpi0EVUP8qMMKa/gnmDa9sc2AKZc07S4l4hGY2zdNGE88AaFzc08OWYffRaNrMWg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U1UBIQu0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U1UBIQu0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62D581F000E9; Wed, 19 Aug 2026 14:53:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787151199; bh=W2EIvkv9Nq32WWVSfwklxxGLToFHgsoCABwz/s4TkD8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=U1UBIQu0ssOyvURDZkHuUnjZuEGlsrJqH+xUIcNmnFhrxDmytdrcG/vlRO8tYBLj6 aqTHL0o5ITTMnnX594JQNTXv+MufvSl1yUMQrjWHne9GuXU9iVu9mxGGsArKKzb176 nAV9kSrU/uady8iPq9hruXqEGPaRFHL7Ta14QTBRSZqPni/Sg3luPYTUbmCXZB+rlw /dh+tWIKxtq9QR6Luk3IP16uffZVs1aNM0vuSO5LRXlDTRZd6Pjsq8cnoPDJV8KUx7 qfPIRTYx2/XJaAmyplVAgid4AuAcJTuixmTA+GbD3MsD1+TVXrNnxCqOZc7IybUIEf eXzQ6wjkVY1Ig== Message-ID: Date: Wed, 19 Aug 2026 16:53:05 +0200 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 Cc: Ekansh Gupta , 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 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> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 19/08/2026 16:49, Rob Clark wrote: > On Wed, Aug 19, 2026 at 7:43 AM Krzysztof Kozlowski wrote: >> >> On 19/08/2026 16:38, Rob Clark wrote: >>> On Wed, Aug 19, 2026 at 7:21 AM Krzysztof Kozlowski wrote: >>>> >>>> On 19/08/2026 15:26, Ekansh Gupta wrote: >>>>> On 19-08-2026 00:43, Krzysztof Kozlowski wrote: >>>>>> On 17/08/2026 06:47, Ekansh Gupta wrote: >>>>>>> This patch series introduces the Qualcomm DSP Accelerator (QDA) driver, >>>>>>> a DRM-based accelerator driver for Qualcomm DSPs. The driver provides a >>>>>>> standardized interface for offloading computational tasks to DSPs found >>>>>>> on Qualcomm SoCs, supporting all DSP domains. >>>>>>> >>>>>>> The QDA driver implements the FastRPC protocol over the DRM accel >>>>>>> subsystem. It uses the same device-tree node structure as the existing >>>>>>> fastrpc driver in drivers/misc/. The approach for binding the QDA driver >>>>>>> to device-tree nodes while coexisting with the fastrpc driver is an open >>>>>>> item described below. >>>>>> >>>>>> No. Grow/replace/improve existing driver instead of coming with a duplicate. >>>>>> >>>>>> That's a standard upstream requirement, basically given on every >>>>>> upstreaming guide. >>>>>> >>>>>> Please watch old talk from Greg - "I Don’t Want Your Code!". >>>>> Posted discussion threads here[1]. Would seek comments from Dmitry, >>>>> Srini as well. >>>>> >>>>> [1] >>>>> https://lore.kernel.org/all/3476b5c3-7983-4994-a901-3d7d8bd75255@oss.qualcomm.com/ >>>> >>>> The rest of the comments is still valid even if you did not acknowledge >>>> them. >>>> >>>> Anyway, regarding above - again, watch the talk from Greg. >>>> >>>> You have ONE driver. Not two. >>> >>> Long term, moving to the common driver framework (which did not exist >>> when fastrpc was first created) seems like a good thing. But does >>> that not allow for some transition period? How can we get from here >>> to there without otherwise breaking userspace? Is there some other >>> precedent elsewhere in other driver subsystems? >> >> Yes, Iris and Venus where we agreed for an exception (two drivers) as >> long as new driver supports old hardware / features. >> >> This is not the case here, right? >> >>> >>> I suppose drm exposing legacy fbdev on top of drm drivers is _sort of_ >>> a precedent if you squint a bit? I'm not really familiar enough to >>> say if that would be reasonable/possible in this case. >> >> Growing old driver does not look complicated itself. The only a bit >> tricky thing is to present somehow exclusive interface to user-space, >> like usage of one disables the second etc. Depending on actual >> differences in that interface. >> >> But having a duplicated driver is a clear no go and it is well known >> upstream requirement. Nothing new here. > > Would it be acceptable as a first step to, by default (ie. when no > cmdline override/etc) for the new driver to bind to new compatibles You have one compatible. > and the existing driver to old? Ie. have both drivers but only one > binds on a given platform? I don't see how is it possible to write such DTS, because - repeating my question - how many hardware blocks is there? I believe only one per given DSP, so how could you have two device nodes? Best regards, Krzysztof