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 8AB6433345A; Wed, 20 May 2026 12:07:33 +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=1779278854; cv=none; b=UbCB+tFnTSruKuPAFytOYOfK+uERkiLYiYk5LVXMpe5lcES56h3GQANqk4tvhJ5CSU844DKLLMjTldN09M9qd8Ud8JMKeowcC+eSI2v9Iep5po3wUD4nHnmltSjdTXeMSmTKb741dvmDUBtg/tlNu/OCER1giABh0gE1chyX2yk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779278854; c=relaxed/simple; bh=anG98z+M4CGyffWaMQ47XSmDrV+He60zSFe5IokcnZI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KnlEWBHlB9pJ1VzVVf8GtV0tdMdpxhn4AdLiGOmvjtY+RSUrP+Whnik6pT6PG737Zqr4mIkrwCMR83alD/Yg9TSNOZdYYk6dH6cLvzvOQuIZM42NerUL55zJQNXGd4LMM3Aw6+sWrb5eRhclXF54jCK1hYVcMOGM5T8Q5TAWxfw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZjYUyx5P; 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="ZjYUyx5P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80ABB1F000E9; Wed, 20 May 2026 12:07:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779278853; bh=PL2Gy1SLLd7c7uyjJl89vc1E1IyawnW8r2RzziHU6Sg=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ZjYUyx5P0LUi9EaMNlyMOFaCQIPPJKZrhI/WRQAyFzEqHADbYdGzZIv870jCcsiZ3 4hLg/vXO3cILluY1QfvPjM/RfNvtAJeuJGixKMaIev5zZQTLpvIgoTD2WrEsyIY7cW O0oNlic10CWPWyCxbbGiqYisTChnrSisObIq2jmqReYDSrhaHdlKcHlFq2UChGMr4p VlqYcoPpeDMIeOsonVW5S493uxxKNlnl/uDfDx3KuoAkeQfvsjOfk+RFNPXOj3EOWw LnCcqRDphXc0RkiErVBOCYbiw3B7VUucFKpUARR86Xn/MZ6C2hUt9MBv26PDBWDVLp x8o1pZ0v1WWNw== Date: Wed, 20 May 2026 19:48:28 +0800 From: Jisheng Zhang To: Krzysztof Kozlowski Cc: Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] spi: dt-bindings: cdns,xspi: add sdma-io-width Message-ID: References: <20260511031732.3199-1-jszhang@kernel.org> <20260511031732.3199-2-jszhang@kernel.org> <20260515-expert-devious-cricket-faff56@quoll> <21d30826-bfe6-44cd-8c89-c1986f539e48@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <21d30826-bfe6-44cd-8c89-c1986f539e48@kernel.org> On Wed, May 20, 2026 at 09:09:55AM +0200, Krzysztof Kozlowski wrote: > On 20/05/2026 01:38, Jisheng Zhang wrote: > > On Fri, May 15, 2026 at 10:00:50AM +0200, Krzysztof Kozlowski wrote: > >> On Mon, May 11, 2026 at 11:17:31AM +0800, Jisheng Zhang wrote: > >>> The cdns xspi controller SDMA data port may support wider I/O width. > >>> Wider I/O width can benefit performance. A simple test with QSPI nor > >>> flash on one arm64 platform: > >>> > >>> 1 byte io width (default): > >>> # dd if=/dev/mtdblock0 of=/dev/null bs=8192 count=1000 > >>> 1000+0 records in > >>> 1000+0 records out > >>> 8192000 bytes (7.8MB) copied, 1.368735 seconds, 5.7MB/s > >>> > >>> 4 bytes io width: > >>> # dd if=/dev/mtdblock0 of=/dev/null bs=8192 count=1000 > >>> 1000+0 records in > >>> 1000+0 records out > >>> 8192000 bytes (7.8MB) copied, 1.088787 seconds, 7.2MB/s > >>> > >>> Improved by 26.3%! > >>> > >>> Add dt binding for sdma-io-width. > >>> > >>> Signed-off-by: Jisheng Zhang > >>> --- > >>> Documentation/devicetree/bindings/spi/cdns,xspi.yaml | 6 ++++++ > >>> 1 file changed, 6 insertions(+) > >>> > >>> diff --git a/Documentation/devicetree/bindings/spi/cdns,xspi.yaml b/Documentation/devicetree/bindings/spi/cdns,xspi.yaml > >>> index 38a5795589de..1fd4b6dfd417 100644 > >>> --- a/Documentation/devicetree/bindings/spi/cdns,xspi.yaml > >>> +++ b/Documentation/devicetree/bindings/spi/cdns,xspi.yaml > >>> @@ -40,6 +40,12 @@ properties: > >>> interrupts: > >>> maxItems: 1 > >>> > >>> + sdma-io-width: > >>> + description: Slave DMA data port I/O width (in bytes) > >> > >> Waht is SDMA? What is Slave DMA? The same? > >> > >> Why this cannot be deduced from the compatible? DMA is fixed per > >> platform and SDMA do not sound like SPI device (so slave in older > >> terminology) property. > > > > in cdns xspi, sdma == slave dma. It can be read by any master, such > > as DMA engine or CPU. Its purpose and usage is similar as the data > > reg in other spi controllers, e.g the DW_SPI_DR in dw spi. > > You did not really answer the questions. > If you mean "Why this cannot be deduced from the compatible?", I think the slave dma port is part of the cdns xspi, so its io width belongs to xSPI device property. >From another side, we have seen such property in other drivers such as the reg-io-width for the dw spi DW_SPI_DR port io width. Thanks