From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bear.ext.ti.com ([192.94.94.41]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VPRXo-00086k-AW for linux-mtd@lists.infradead.org; Fri, 27 Sep 2013 06:28:52 +0000 Message-ID: <5245256F.1060407@ti.com> Date: Fri, 27 Sep 2013 11:57:59 +0530 From: Sourav Poddar MIME-Version: 1.0 To: Huang Shijie Subject: Re: [PATCHv2] drivers: mtd: devices: Add quad read support. References: <1380191565-28640-1-git-send-email-sourav.poddar@ti.com> <1380193243.28494.51.camel@i7.infradead.org> <524418AF.3030306@ti.com> <5244F003.6040502@freescale.com> <52451D85.90404@ti.com> <524522A7.2090202@freescale.com> In-Reply-To: <524522A7.2090202@freescale.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit Cc: artem.bityutskiy@linux.intel.com, balbi@ti.com, broonie@kernel.org, linux-mtd@lists.infradead.org, computersforpeace@gmail.com, David Woodhouse List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Friday 27 September 2013 11:46 AM, Huang Shijie wrote: > 于 2013年09月27日 13:54, Sourav Poddar 写道: >> On Friday 27 September 2013 08:10 AM, Huang Shijie wrote: >>> 于 2013年09月26日 19:21, Sourav Poddar 写道: >>>> If the pupose of LUT is to just set the dummy cycles, and vf610-twr >>>> hardware state machine does not have have any other dependency >>>> on LUT, this patch should work. >>> Hi Sourav & David: >>> >>> The key issue about the vf610-twr is that: >>> [0] Use the LUT makes the Quadspi driver more efficiency. >>> [1] the vf610-twr needs to know the SPI NOR commands for Page >>> Program. >>> Why? because the driver can not change the size of >>> write-buffer from 256bytes to the 64byte(TXFIFO SIZE). >> Not clear about this. But, you will anyway know what you are using >> from the m25p80 side rite? > > The TX FIFO is 64 bytes in the Vybrid, but the Page Program may > writes 265 bytes per time. > > If the TX FIFO is smaller then the size of Page Program, we have to > wait until the Write(64bytes) is finished. > If we do not wait, the write will not finished. > > hmm..I think thats should be handle in your controller by checking t->tx_buf and see what command is used. > >>> [2] the dummy and other things. >>> >> Dummy stuffs can be handled from m25p80 side rite? fast read dummy >> cycle support is already there. While, >> $subject patch adds it for quad read. > The m25p80 can only handle the 8bit dummy now, such as fast read and > QOR(0x6b). > > But it can not handle the QIOR (0XEB, may needs 4bit dummy), and can > not handle the DDR QIOR(0XED, may > needs 6bit dummy). > Correct, as I explained in one of my comment on v1, that the creating of a quad api is justified for this reason itself, since there are other quad commands wth different dummy cycle requirements. We can build on top of $subject patch and try to add support for other quad commands also. ? > thanks > Huang Shijie >