From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Wegner Date: Fri, 23 Apr 2010 17:18:29 +0200 Subject: [U-Boot] convention for SPI dummy data? In-Reply-To: <201004231108.11427.vapier@gentoo.org> References: <20100423084307.GN20047@leila.ping.de> <201004231108.11427.vapier@gentoo.org> Message-ID: <20100423151829.GO20047@leila.ping.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Mike, On Fri, Apr 23, 2010 at 11:08:10AM -0400, Mike Frysinger wrote: > On Friday 23 April 2010 04:43:07 Wolfgang Wegner wrote: > > However, one of the things I had to change was the dummy data sent > > out by SPI for read-only transactions. The original driver had all > > zeros, for SD/MMC all ones (0xFF) is needed. > > > > Is such a change acceptable, or is there any configuration option/flag > > I could use? > > if it isnt part of the SPI/MMC spec, use a config option named like IDLE_VAL. the problem exists in the (coldfire) SPI driver, not in the MMC/SD code. (For SD, the spec IMHO clearly states 0xFF for all idle transfers.) > changing the default to 0xff is OK i think. I could add CONFIG_SPI_IDLE_VAL and default it to 0x0 in the coldfire SPI driver. In case one wants to use MMC/SD with this driver, one could then add CONFIG_SPI_IDLE_VAL as 0xFF in the board to override it. (Only pitfall is that the current 0x0 is used for 8- as well as 16-bit transfers...) ok? > -mike Regards, Wolfgang