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[86.49.110.70]) by smtp.gmail.com with ESMTPSA id v8sm132964293wrq.53.2019.01.28.03.03.01 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 03:03:02 -0800 (PST) Subject: Re: [PATCH v7 1/2] spi: Add Renesas R-Car Gen3 RPC-IF SPI controller driver To: masonccyang@mxic.com.tw Cc: bbrezillon@kernel.org, broonie@kernel.org, Geert Uytterhoeven , Simon Horman , juliensu@mxic.com.tw, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-spi@vger.kernel.org, sergei.shtylyov@cogentembedded.com, zhengxunli@mxic.com.tw References: <1548227352-14910-1-git-send-email-masonccyang@mxic.com.tw> <1548227352-14910-2-git-send-email-masonccyang@mxic.com.tw> <67fa5f94-886b-f09c-c93d-832e427ffec8@gmail.com> <0b3ea94f-a4f3-0780-301b-f88ff2ad2fb1@gmail.com> From: Marek Vasut Openpgp: preference=signencrypt Message-ID: <2d762c16-d714-9171-9450-b6adf1a6509c@gmail.com> Date: Mon, 28 Jan 2019 12:03:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/28/19 2:38 AM, masonccyang@mxic.com.tw wrote: > Hi Marek, Hi, >> "Marek Vasut" >> >> >> > +module_platform_driver(rpc_spi_driver); >> >> >> >> >> >> RPC is not a SPI controller, it's a SPI and HF controller. >> >> >> >> >> >> Also, how difficult will it be to add the HF support ? >> >> > >> >> > One of my customers needs RPC SPI driver for our company's >> >> > Octal-Flash,MX25UW51245G. >> >> > We don't have HF product and hope you could understanding. >> >> >> >> I am worried that when we need to add RPC HF support (which is what all >> >> boards but the D3 Draak use), we will have to rewrite the entire driver >> >> and/or convert it to MFD and that would be a tremendous > undertaking. I'd >> >> prefer to have the driver ready for the HF addition before it's > accepted >> >> upstream. >> >> >> > >> > I think maybe your concerned would be happened only if HF driver > goes with >> > spi-mem layer. >> > >> > A comment for HF from Daniel Fishman. FYR. >> > >> > https://www.quora.com/What-is-a-hyper-flash-memory-and-how-is-it- >> different-from-normal-flash-memory >> >> I have a decent idea what HF and SPI NOR are, since I wrote the RPC >> driver for both HF and SPI mode for U-Boot (as I mentioned earlier). >> >> The HF in Linux would use the CFI NOR part of MTD framework. My concern >> is that when we need to add HF support into this driver, this driver >> will have to be basically rewritten, since the architecture won't allow >> for that. I'd like to avoid that, since the majority of Gen3 boards, >> expect for the D3 Draak, use RPC in HF mode. > > FYI~ > > MX25UW51245g(64MByte Octa)                      S26KL512S(64MByte HF) >    8 IO                                                  8 IO > 200MHz DDR@1.8v                                   166MHz DDR@1.8v > > support Read-while-write                       Not support > good for OTA,etc > powerful application What does that mean ? -- Best regards, Marek Vasut