From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1g1v7w-00021H-Qt for linux-mtd@lists.infradead.org; Mon, 17 Sep 2018 15:07:54 +0000 Date: Mon, 17 Sep 2018 17:07:31 +0200 From: Boris Brezillon To: naga suresh kumar Cc: nagasure@xilinx.com, cyrille.pitchen@wedev4u.fr, marek.vasut@gmail.com, dwmw2@infradead.org, computersforpeace@gmail.com, boris.brezillon@free-electrons.com, linux-mtd@lists.infradead.org Subject: Re: [RFC PATCH 0/5] RFC for Zynq QSPI Message-ID: <20180917170731.078e3d4f@bbrezillon> In-Reply-To: <20180917170522.0312ae8c@bbrezillon> References: <1521807722-21626-1-git-send-email-nagasure@xilinx.com> <20180917170522.0312ae8c@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 17 Sep 2018 17:05:22 +0200 Boris Brezillon wrote: > Hi Naga, > > On Mon, 17 Sep 2018 16:08:26 +0530 > naga suresh kumar wrote: > > > Hi all, > > > > Can i write the Zynq QSPI driver under the new spi/mem framework? > > Yes, you should. > > > As i said, it needs tweaking the mtd->size and spi read/write addresses. > > Can you elaborate a bit on why you think this is needed? Did you look > at [1]? Maybe it will prevent us from exposing the flash size at the > spi-mem level. > > > Can somebody share your thoughts on this(Adding Zynq QSPI Dual parallel and > > stacked)? > > I always have a hard time with this naming. I guess stacked is when you > have 2 chips sharing the same I/O bus, and parallel is when you have 2 > chips with one taking all of the I/O and the other taking the other ^half of the I/O bus and the other one > half. Is that correct? > > If it is, then stacked mode should be easy to support (it's just a > matter of patching the spi layer to allow passing several CS lines to a > single device (in case of DT parsing, it means reg = <0 1> implies CS 0 > and 1 are assigned to the same device. For the parallel, I don't have a > solution yet. > > Anyway, I'd suggest that you start with something simple (a spi-mem > driver supporting ->exec_op() in Single/Dual/Quad mode), and build on > top of that for the advanced features you're mentioning here. > > Regards, > > Boris > > [1]http://lists.infradead.org/pipermail/linux-mtd/2018-June/081460.html