From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9663419D880; Thu, 10 Oct 2024 18:14:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728584068; cv=none; b=F6EYHdmkQ1+ACs2519ns9m2M4AxsbHEA6bgfo6UQviWGeypoaXIDsSdfjSxIfCM1ulM4zhZRRNt1JcwzWqC+xEuVM//12ef0yGT9hrOyiUuXL7Q9UJowF2VWdUqgQcdJMqGaOzMHBiGKD1NCodZTycA6br2G0UClbO63B5YR7Jc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728584068; c=relaxed/simple; bh=O2rfQPpIZwjz0HkgGVQfisi/l8/F1UC2p3XQEvowOoA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AWLjhcGI03xzRTbuqDLypL0njUYYp3Buz70LjC8WvUoRbbBClVaylgj7+OGoWxCCSCQHT7AigDut6hmbsZnMoBQkeWSv91BadqYMpy8/u4W05YibrIsZinIk+BYHmSx20/A44A+oFE7YSO4DhSGP98iMTFCGnGOmokyDto2DlxY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n5pltNnm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="n5pltNnm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8794C4CEC5; Thu, 10 Oct 2024 18:14:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728584068; bh=O2rfQPpIZwjz0HkgGVQfisi/l8/F1UC2p3XQEvowOoA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=n5pltNnm0sgSnfDqpzVrTGsr7RbNS/fwjOl+4d7QLvPd1uzH2cYRXtb5weHAmpxlQ jKwf2Ob67DFCCoY5VGVwoci4fl3ghfVrvutEAFLTnnaJJW4HkwwDvRSnBA6M6jYKcq 8zescVdSDG+INd2sj7yoS/ht2JwdkiRMP4FsDfK/ex/uEzQku7ORWp+39kDHvxbHnk ykJ1Tdm18j0zADby2zO9gi02UCi3ML65ZQjXTxl7QTtPJl5j+Q9QP9aR+RAxcKzrGP pB4S9f5I11S052Vv2ZOu2B0ItEZJixnh7eOlH0FzKmofnPTtx2ePok0yDiXxGueCL8 Kk9IBB8323Nfg== Date: Thu, 10 Oct 2024 13:14:26 -0500 From: Rob Herring To: Amelie Delaunay Cc: Vinod Koul , Krzysztof Kozlowski , Conor Dooley , Maxime Coquelin , Alexandre Torgue , dmaengine@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/11] dt-bindings: dma: stm32-dma3: prevent linked-list refactoring Message-ID: <20241010181426.GA2107926-robh@kernel.org> References: <20241010-dma3-mp25-updates-v1-0-adf0633981ea@foss.st.com> <20241010-dma3-mp25-updates-v1-4-adf0633981ea@foss.st.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241010-dma3-mp25-updates-v1-4-adf0633981ea@foss.st.com> On Thu, Oct 10, 2024 at 04:27:54PM +0200, Amelie Delaunay wrote: > stm32-dma3 driver refactors the linked-list in order to address the memory > with the highest possible data width. > It means that it can introduce up to 2 linked-list items. One with a > transfer length multiple of channel maximum burst length and so with the > highest possible data width. And an extra one with the latest bytes, with > lower data width. > Some devices (e.g. FMC ECC) don't support having several transfers instead > of only one. > So add the possibility to prevent linked-list refactoring, by setting bit > 17 of the 'DMA transfer requirements' bit mask. > > Signed-off-by: Amelie Delaunay > --- > Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml > index 5484848735f8ac3d2050104bbab1d986e82ba6a7..38c30271f732e0c8da48199a224a88bb647eeca7 100644 > --- a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml > +++ b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml > @@ -99,6 +99,9 @@ properties: > -bit 16: Prevent packing/unpacking mode > 0x0: pack/unpack enabled when source data width/burst != destination data width/burst > 0x1: memory data width/burst forced to peripheral data width/burst to prevent pack/unpack > + -bit 17: Prevent linked-list refactoring > + 0x0: don't prevent driver to refactor the linked-list for optimal performance > + 0x1: prevent driver to refactor the linked-list, despite not optimal performance Driver settings don't belong in DT. Perhaps reword it in terms of h/w constraints (i.e. single transfer limitation). > > required: > - compatible > > -- > 2.25.1 >