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 CDC3C2EBB84; Tue, 2 Jun 2026 12:48:40 +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=1780404521; cv=none; b=uAWemznU55oatuFPUEGc5VjhOOJuQJQ69gauyRCY4tXzVzPqDi0vN2LA7k9g/QMPLKFUZV2sslgu+E6yzxU9Jeh+resPypMGob91QsHL281KmjSDkgOGDrzmv3ONl9Xv+nRN6AEIC0bpkCBJK+uiux6/Za4HJBamvIcsIIxel3Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780404521; c=relaxed/simple; bh=Fg12JKOKNMh3/thE/r8uizOGwJO63KCn7Sx3hQbAgYQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cG4AnaGAiPPpw2KvBJmeP9yxdxobm/Rj7cEGR3dbDpDF5sp5594YlDp6uReyxOOsq90vM5QFsHSbI+++eMChpM2vDnTFDz2j2DVEUqLkbl56k1ZItSNAhpauLh/8bfOIZnMJP1/RHpz4wF7nP/fpPXI5tupHk/CSSSNhXOdTVm8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FUZIcGLc; 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="FUZIcGLc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4FE101F00893; Tue, 2 Jun 2026 12:48:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780404520; bh=pze10/tu3dHWvLBfvau7q+6nPElM7Mvl4SghPnBGxNs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=FUZIcGLctRNxM7xHAlnw4cEgPGBKk9xPuZn6eOu70lgSgljFAdZgJbj/trJFyTaKu ETHmmsmrRw8dqd8Wacr5Xud37WYzn9dVBZVEAAWDM1p46TNrwjM9YIe0kfWz1ZcHah DPpq9DFOXvHpKAEL5jFAe5kxtqgpvE0p/7zs3zFkhWeQOHF69ZK6pHF0WAbQj9z9+U pNrHKQiVQdWIBVF0e2/WCrzFRvJE80Bkj2mmTy5TqV5CqCsBR0FNwN5RisJnRFcQt7 SL07fm+QKej/tfuljZl7NvAqRFFYr655fIc2vmnFKq+P2BNktdzA/eOUW+eod1Q7Ds YYjtWCNx0m+xQ== Message-ID: <71045249-bd49-4a95-ba17-589cee255eda@kernel.org> Date: Tue, 2 Jun 2026 14:48:34 +0200 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 v3 02/13] spi: dt-bindings: cdns,qspi-nor: add PHY tuning pattern partition property To: Miquel Raynal , Santhosh Kumar K Cc: broonie@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, richard@nod.at, vigneshr@ti.com, pratyush@kernel.org, mwalle@kernel.org, takahiro.kuwano@infineon.com, linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, praneeth@ti.com, u-kumar1@ti.com, a-dutta@ti.com References: <20260527175527.2247679-1-s-k6@ti.com> <20260527175527.2247679-3-s-k6@ti.com> <20260530-original-peccary-of-cubism-af68ed@quoll> <2f091813-fa28-407f-892d-bbbbe3cac4e4@ti.com> <063fe976-9a28-4670-90df-921fbc1c3a8c@kernel.org> <20260601-stirring-tested-mayfly-e97c14@quoll> <4a570d36-dda6-4f3d-9c16-d3e57ac55f1c@ti.com> <87mrxd15mm.fsf@bootlin.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 02/06/2026 14:36, Miquel Raynal wrote: > Hello, > >>>>>> I also have doubts that this is per-device property. Your commit msg >>>>>> suggests it is per controller. >>>>> >>>>> This is a per-device property. It is consumed by the controller driver >>>>> only to locate and retrieve the offset of the PHY pattern partition >>>> >>>> So with two devices on a bus, you need two separate partitions for tuning? >> >> Each SPI NOR flash device needs a partition to store PHY tuning >> pattern. > > If I may try to explain a bit what is behind, the read tuning procedure > is about reading data from the spi memory cache (some kind of internal > SRAM) over and over again, while tuning the controller parameters until > we get the best stability (the controller driver knows the pattern it > must get). While SPI NAND chips have "write to cache" opcodes that could > be used to load the pattern into the chip without any actual read from > the memory array, this is not possible with SPI NOR devices which do not > have such capability. Since we want to keep this training procedure > memory agnostic (and also somewhat simple), we shall expect one pattern > per memory. Can pieces of above be captured in commit msg, so it will be clearer to folks without domain knowledge? Best regards, Krzysztof