From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Sat, 11 May 2013 08:42:16 -0600 Subject: [U-Boot] [PATCH 1/2] SPI: Add support for preamble bytes In-Reply-To: <1363933766-6555-2-git-send-email-rajeshwari.s@samsung.com> References: <1363933766-6555-1-git-send-email-rajeshwari.s@samsung.com> <1363933766-6555-2-git-send-email-rajeshwari.s@samsung.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Fri, Mar 22, 2013 at 12:29 AM, Rajeshwari Shinde wrote: > A SPI slave may take time to react to a request. For SPI flash devices > this time is defined as one bit time, or a whole byte for 'fast read' > mode. > > If the SPI slave is another CPU, then the time it takes to react may > vary. It is convenient to allow the slave device to tag the start of > the actual reply so that the host can determine when this 'preamble' > finishes and the actual message starts. > > Add a preamble flag to the available SPI flags. If supported by the > driver then it will ignore any received bytes before the preamble > on each transaction. This ensures that reliable communication with > the slave is possible. > > Signed-off-by: Simon Glass > Signed-off-by: Rajeshwari Shinde Acked-by: Simon Glass