From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (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 DC5762F5A0C for ; Thu, 13 Nov 2025 15:32:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763047942; cv=none; b=Ag6eGG2Kazc8hP+uNs7sthZVf1zt9xCaZnggis4BoNdQv6RICS8/tZwu8sZWTmwnvLYVO6bIfAFWBDACfe3bdmI3PGhlv24f7gK4fVqKARTVyhRIjwH9OfqrqlYmSWYGlQJEpxWMnplNAyd5kA0WrwXldnsp0yxxF4346J5K8VY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763047942; c=relaxed/simple; bh=+hzEjqiEbKk7CqzqS4tCem+ocMq5Ym5NmnnnbaFZuOQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OXHhOX7Gccz++sDmOyNUPC2l0uqq7k+dJAAH6l97nohgzt4A791EEmv8XSHUwIMlj/n3xYHFRUn/3Q68fU/LN2yNiQnKmLAAnNtJF5llYHguTdZy6oCE1bMFgPA0yAJgO8yne7+WbP7klqom0dAhrbHTURzpdZwYMQUZ1IMZAlc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nrVDHH0J; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nrVDHH0J" Message-ID: <3f415ff1-834e-4544-a093-dcb4fd25d5c9@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763047937; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xbfnACF5OTG+C22l5VOv6/tW6U39u4VS9uuFSVlj28M=; b=nrVDHH0JXKy1x6XMICO/SM2U1WPndKvVMdCPswy7SV0uuTgfLfRi/4fyvij+HH7K3TlbB/ 7voKQ8Ftz5yo+WcxScG5yq+NMeZUoaT7k5I4zN6B2qwKf13hZyoiEZUehJ5OeGSm3RFg9D ABZhBX2EsB9sUb5v9N5hee8lF7qwnxE= Date: Thu, 13 Nov 2025 10:32:05 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] mtd: spi-nor: Enable locking for n25q00a To: Miquel Raynal Cc: Tudor Ambarus , Pratyush Yadav , Michael Walle , linux-mtd@lists.infradead.org, Richard Weinberger , linux-kernel@vger.kernel.org, Vignesh Raghavendra References: <20251006223409.3475001-1-sean.anderson@linux.dev> <4888cefa-e8be-4f0d-9d4a-c82f9ff6cda0@linux.dev> <26a795ac-e6ff-4363-a8b9-38793a9be794@linux.dev> <33cbbac1-c247-4644-b555-998eea6e8305@linaro.org> <92e99a96-5582-48a5-a4f9-e9b33fcff171@linux.dev> <871pm3iegf.fsf@bootlin.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: <871pm3iegf.fsf@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/12/25 08:10, Miquel Raynal wrote: > Hello Sean, > >> # flash_lock -u /dev/mtd/by-name/spi0.1 >> # flash_lock -i /dev/mtd/by-name/spi0.1 >> Device: /dev/mtd/by-name/spi0.1 >> Start: 0 >> Len: 0x8000000 >> Lock status: unlocked >> Return code: 0 >> # test() { >>> mtd=/dev/mtd/by-name/$1 >>> start=$(($2 * 64 * 1024)) >>> size=$(($3 * 64 * 1024)) >>> dd if=/dev/urandom of=$1 bs=64k count=$3 status=none && \ >>> mtd_debug erase $mtd $start $size && \ >>> mtd_debug write $mtd $start $size $1 && \ >>> dd if=$mtd bs=64k skip=$2 count=$3 status=none | sha256sum $1 - && \ >>> rm $1 >>> } > > I am also working on locking these days, have you already started > writing extra SPI NOR Documentation/process based on this thread? I haven't started writing anything. > I am also trying to clarify what is expected and what the API somehow > does, as it was not fully clear for me at first sight. I agree, as you could probably have figured out. >> # flash_lock -u /dev/mtd/by-name/spi0.1 >> # test spi0.1 64 >> 83a8dc6125ec9672d18f7f18f92e16f867354dbe8e2f3b0aca52b9d0ad7d8ffe spi0.1 >> 83a8dc6125ec9672d18f7f18f92e16f867354dbe8e2f3b0aca52b9d0ad7d8ffe - >> # flash_lock -l /dev/mtd/by-name/spi0.1 $((1024 * 64 * 1024)) 1024 >> # flash_lock -i /dev/mtd/by-name/spi0.1 >> Device: /dev/mtd/by-name/spi0.1 >> Start: 0 >> Len: 0x8000000 >> Lock status: unlocked <<<< Wrong! > > This isn't wrong, even though at a first glance the output is > misleading. The API apparently does not gives you all the > locked/unlocked sectors, it is way more basic than that: it tells you > whether the full range you asked for is indeed locked. Yeah, I figured that out eventually. Actually, the most surprising thing to me is that the lock/unlock APIs are not incremental. That is, if I have a flash of 8 seconds, and sectors 0-3 are locked and I lock sectors 0-1, it will say "well, sectors 2-3 should be unlocked now, but we're not allowed to unlock during a lock operation" and fail to lock. I would have expected it to say "sectors 0-1 are already locked so we don't need to do anything". The only way to go from sectors 0-3 to 0-1 being locked is to issue an *unlock* on sectors 2-7. Conversely, if what you wanted to do was ensure sectors 2-3 were unlocked, you can't do the naive thing and unlock sectors 2-3, since that will try to lock sectors 0-1 and 4-7, the latter being disallowed in an unlock operation. So you actually have to unlock sectors 2-7. And knowing what to do is complicated by ISLOCKED only returning a boolean instead of just telling userspace what sectors are locked (which must be a small finite set of ranges (usually one) on all flashes I'm familiar with). > When you run "# flash_lock -i /dev/mtd/by-name/spi0.1", you privide no > start/length values to the command. Hence, the defaults are picked: the > entire device is considered for the check. The tool asks the kernel > whether the range 0-0x7ffffff is *fully* locked. Answer is no, it is not > fully locked. > > In the kernel there are two helpers for that, and they won't give you > opposite results all the time: > - is locked: > - returns true if the given range is fully locked > - returns false otherwise > - is unlocked: > - returns yes if the given range is fully unlocked > - returns false otherwise > > So if you want the tool to tell you "yes", you should instead use the > exact range you locked (1024-2047) or any subset of it. > > Thanks, Miquèl