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 E88AA390982; Mon, 16 Mar 2026 16:56:07 +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=1773680168; cv=none; b=s7WIRLvjwPL4+c2RKBDn+YwaCuYe44RgnrZczYvr9qJwVXvnHVUoFu4RKKZqLczm06m+pDjlH1h2rO+otOTuEsibEHAXbxUGzpg18kucBQCuljAwSSvywYthGMgNZXM9xcKTRq61PWwvuDbdvQiHVW6u/6ug0Rl/UwHxmGvQCR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773680168; c=relaxed/simple; bh=HXdFbCFmM0I4exfloxptKO0VbCx6T+9FA4oPkwUoYSY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=a/Uw+oZUDHk5OIwebAzVt7tdvPEeHDs/WSn0ca9GMq3eG7xkeNGP7EI62uEOBH95A5n3sagw7jjzyZaJ6Jd7GbzpCIo0cFGJuDBl3n75uvx6IJbO4mzrw2w68fShjBUzqNibhBOqjWfoRIaFm4btw3hUQHOvhK3OlqWmUUad55k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EhFuTEhg; 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="EhFuTEhg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42C13C19421; Mon, 16 Mar 2026 16:56:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773680167; bh=HXdFbCFmM0I4exfloxptKO0VbCx6T+9FA4oPkwUoYSY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=EhFuTEhgOTzf9+BK/w6J7I7fy3Gv4HVJ4rpbms03AocCnKAFr+4UgTCymnaaThQcj Okku9IyAuGxfRrssByDamIcvAxE88GIQ2jufzbFWDv/+CqBHgK/F4riIWsBzjPQXuQ 9hGky2ZXxyTqoPcprjL/ZZ6yRBcHUnpzdQ35GrRwE29P27RIEimdX5lPLtibTiPKna AjFZl5HUafkQS0BKIhpYMt2qRnl3GOhE2nJzIJ60R/uvELOh6YUQ0csn6CX/qkablV reSDpLlQElmWYCY1nXfdbXXml+wo7N3k8Opx8rj/t4COP0W38Ew5V5RE8KZTkhCW1K lQpAqV8phiIDg== Message-ID: Date: Mon, 16 Mar 2026 17:56:02 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add spi-miso-mosi-loopback To: Francesco Dolcini Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mark Brown , Francesco Dolcini , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org References: <20260316073547.11437-1-francesco@dolcini.it> <20260316073547.11437-2-francesco@dolcini.it> <20260316085751.GA23443@francesco-nb> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 16/03/2026 09:57, Francesco Dolcini wrote: > Hello Krzysztof, > thanks for taking the time to answer this > > On Mon, Mar 16, 2026 at 09:36:42AM +0100, Krzysztof Kozlowski wrote: >> On 16/03/2026 09:35, Krzysztof Kozlowski wrote: >>> On 16/03/2026 08:35, Francesco Dolcini wrote: >>>> From: Francesco Dolcini >>>> >>>> Add a compatible to describe a single wire loopback between SPI MISO and >>>> MOSI signals. >>>> >>>> Link: https://lore.kernel.org/all/20260310133254.GA51497@francesco-nb/ >>>> Signed-off-by: Francesco Dolcini >>>> --- >>>> Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++ >>>> 1 file changed, 2 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml >>>> index a482aeadcd44..2cb973c157f6 100644 >>>> --- a/Documentation/devicetree/bindings/trivial-devices.yaml >>>> +++ b/Documentation/devicetree/bindings/trivial-devices.yaml >>>> @@ -432,6 +432,8 @@ properties: >>>> - socionext,uniphier-smpctrl >>>> # SparkFun Qwiic Joystick (COM-15168) with i2c interface >>>> - sparkfun,qwiic-joystick >>>> + # Single wire loopback between SPI MISO and MOSI signals >>>> + - spi-miso-mosi-loopback >>> >>> If you decided to go against my approach, then at least document it in >>> proper place - incomplete-devices - so this won't be ever used in DTS. >>> >> >> ... and then you will notice existing linux,spi-loopback-test, so >> explain the differences and why spi-loopback-test cannot be used for >> your loopback test. > > Yes, this spi-loopback-test will work. > > I was not aware of it (no-one mentioned it in the email thread I opened) > and I misread your answer as an alternative suggestion, and not as a nack. > > There is still an open question, I can any driver probe/bind to the > actual SPI device? My plan, once this discussion is settled, is to send > patches to add dtso file enabling this test, however, according to > trivial-devices.yaml, I cannot submit such a DT file using I think you meant incomplete-devices and then yes, such DT upstream is not allowed. > linux,spi-loopback-test as a compatible. > > On the actual HW I have a pins header and a wire between MISO/MOSI. pins header, if I understood correctly what you are talking about, is a connector. Connecting there a jumper to short circuit there is out of scope, because it is not part of the board. Thus cannot be send upstream DTS, unless it is really embedded in the design like USB-A dongles which could not be removed by end user. Otherwise you could say that every evalkit board can have such device, because they all have pin headers... > > I am clearly missing something obvious, any advise is appreciated. Describe your hardware... Nothing in this patchset helps in understanding it. Best regards, Krzysztof