From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-fx0-f49.google.com ([209.85.161.49]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1O7YEu-0005Jy-9R for linux-mtd@lists.infradead.org; Thu, 29 Apr 2010 18:13:33 +0000 Received: by fxm17 with SMTP id 17so1254412fxm.36 for ; Thu, 29 Apr 2010 11:13:30 -0700 (PDT) Subject: RE: [PATCH] sst25l.c: simplify reading the device ManID/DevID From: Artem Bityutskiy To: H Hartley Sweeten In-Reply-To: <0D753D10438DA54287A00B0270842697636E305B2F@AUSP01VMBX24.collaborationhost.net> References: <0D753D10438DA54287A00B0270842697636D85BD7C@AUSP01VMBX24.collaborationhost.net> <1272519398.7750.67.camel@localhost> <0D753D10438DA54287A00B0270842697636E305B2F@AUSP01VMBX24.collaborationhost.net> Content-Type: text/plain; charset="UTF-8" Date: Thu, 29 Apr 2010 21:07:46 +0300 Message-Id: <1272564466.2593.3.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: "linux-mtd@lists.infradead.org" , "ryan@bluewatersys.com" , "andre@bluewatersys.com" , David Woodhouse , Linux Kernel Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2010-04-29 at 12:11 -0500, H Hartley Sweeten wrote: > On Wednesday, April 28, 2010 10:37 PM, Artem Bityutskiy wrote: > > On Tue, 2010-04-20 at 18:17 -0500, H Hartley Sweeten wrote: > >> The Read-ID command will continuously output the Manufacture ID and Device ID > >> until the command is terminated by a low to high transition on the CE# pin. > >> We can take advantage of this in the sst25l_match_device routine by reading > >> both bytes in one spi_write_then_read transaction. > >> > >> Signed-off-by: H Hartley Sweeten > >> Cc: David Woodhouse > >> Cc: Andre Renaud > >> Cc: Ryan Mallon > > > > Pushed to l2-mtd-2.6.git / dunno. > > Artem, > > I have discovered that the Read-Status-Register command has the same problem. > With the SST25L SPI flash chips, if the chip enable is deasserted after sending > a command that command will get aborted. > > I ran across this while testing a new spi master driver for the ep93xx on an > EDB9307A dev board. That board uses the processors SFRMOUT signal as part of > the chip select logic. Unfortunately the ep93xx only asserts the SFRMOUT > signal as long as the spi transmit fifo contains data. As soon as the last > bit is clocked into the receive fifo it gets deasserted. Many of the other > ep93xx based boards have that same issue. > > I have an updated patch that changes both of these into one synchronous message > which fixes the sst25l_status and sst25l_match_device functions. These changes > should be transparent to any users of this driver. > > Could you drop the current patch and I will submit the updated one for review? Of course, just send it. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)