From mboxrd@z Thu Jan 1 00:00:00 1970 From: nicolas.ferre@atmel.com (Nicolas Ferre) Date: Thu, 20 May 2010 15:11:56 +0200 Subject: Support Question In-Reply-To: References: <1274199223.1763.0.camel@ubuntu.ubuntu-domain> Message-ID: <4BF5351C.80306@atmel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Le 19/05/2010 19:06, Amit kumar : > Dear Experts, > > I am using SBC 9260 for development of a data acquisition platform. I am > using the SPI for data acquisition through 14 bit ADC slave. Currently > my board has debian 5.0 kernel version 2.6.30. I am using the spidriver > (spidev )for using the SPI on the board in master mode . Everything is > working fine and I am able to send and receive data . The only problem > is between the activation and deactivation of chip select.It takes > around 70microseconds for chipselect deactivation and then activation . > Since speed of my 4 channel ADC is 1MSPS so i need to bring down delay > as minimum as possible. I checked out the value of the registers > DLYBCS , DLYBCT , DLYBS and all are indicating the values 0. > > Therefore I don;t have any idea from where the delay is being > introduced. Is it a problem of OS or there is nythng else involved . > Kindly guide me through this . I need urgent help .... any information > abt delay is welcome. In the atmel SPI driver, chipselect are managed by GPIO and not automatically by the IP. I think that this is why you experience such delays. I am not totally aware about the reasons for this hand-made management but I guess that you can find information on this mailing-list... Best regards, -- Nicolas Ferre