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 28A3A212F0E for ; Thu, 7 Nov 2024 17:00:24 +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=1730998825; cv=none; b=UtcZj/iq4JuZpQeD6j4R24YQJ8p/8dB2YsDNIhpEHaaZCWGBR2UdVp5L5oz5ZewHBPwdlGBIR+vVoATczn/zkb61HOElhQv6bm8YGffsQ5y0L1fh2M+U5tDnsAehLYlgxlk5om1mqml2BrKApDd6SV7JzjEyp6jWoKRfeQP1vRg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730998825; c=relaxed/simple; bh=fmEMZSN8aYDktJAftW6kTuaO7wJAwwzSFJuKFKEOrmI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=LbpFsHe1QKn/5SDuQKzkCi+EdS/dg8XVv68zmkoCkh5KODyy0+jflrHfYK+zpOCZ4bDTYUYIPxJUcgDJJUdZ/WdVUUZXQUJbpnJMGqH4ZZfJ45MXhGvhAtAWVoi1rcs0OMdy0V91Ts9VKP7bKbinfXAkVN3C+bYZct5PF9Hlv5M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bXaGhoDS; 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="bXaGhoDS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 204B8C4CECD; Thu, 7 Nov 2024 17:00:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730998824; bh=fmEMZSN8aYDktJAftW6kTuaO7wJAwwzSFJuKFKEOrmI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=bXaGhoDSo3pT7F+q6VnOjjxAJKmMyTf3z43Vw6z3BrqOuoGzRAup2kUvvObIE3bsx YmMIgnVEo7EwHtOKAmdylTlqn6vThURcB8YPWkE58fsaQqXgyaiqptHx/ERu0tZP0M /wxwRFenyvfTGxbp1M6NqafnaH6cKXWDL7gB1Cz8taM6FICIaKlJCsbR6GZ449xv4Z AFHHO0Q0j2D0JuSkw5muppQSdEz5lsitrJjEecaHNXR1Yx+bR4rJqtd36F+bbdAv4+ ZWO0a0kZQoFMBoAWQQNckpCCnRzXQOemPJB2EEu/UMgA7tt0LFchvRLD90gh1AleDo f0NyZ8bXMlHtw== From: Pratyush Yadav To: Cheng Ming Lin Cc: tudor.ambarus@linaro.org, pratyush@kernel.org, mwalle@kernel.org, miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, alvinzhou@mxic.com.tw, leoyu@mxic.com.tw, Cheng Ming Lin Subject: Re: [PATCH] mtd: spi-nor: core: replace dummy buswidth from addr to data In-Reply-To: <20241107093016.151448-1-linchengming884@gmail.com> (Cheng Ming Lin's message of "Thu, 7 Nov 2024 17:30:16 +0800") References: <20241107093016.151448-1-linchengming884@gmail.com> Date: Thu, 07 Nov 2024 17:00:21 +0000 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Nov 07 2024, Cheng Ming Lin wrote: > From: Cheng Ming Lin > > The default dummy cycle for Macronix SPI NOR flash in Octal Output > Read Mode(1-1-8) is 20. > > Currently, the dummy buswidth is set according to the address bus width. > In the 1-1-8 mode, this means the dummy buswidth is 1. When converting > dummy cycles to bytes, this results in 20 x 1 / 8 = 2 bytes, causing the > host to read data 4 cycles too early. > > Since the protocol data buswidth is always greater than or equal to the > address buswidth. Setting the dummy buswidth to match the data buswidth > increases the likelihood that the dummy cycle-to-byte conversion will be > divisible, preventing the host from reading data prematurely. Makes sense. Reviewed-by: Pratyush Yadav -- Regards, Pratyush Yadav