On Mar 7, 2011, at 3:41 AM, Stefano Babic wrote:
On 03/03/2011 04:48 AM, Priyanka Jain wrote:
- Timeout counter value is set as DTOCV bits in SYSCTL register
For counter value set as timeout, Timeout period = (2^(timeout + 13)) SD Clock cycles
- As per 4.6.2.2 section of SD Card specification v2.00, host should
cofigure timeout period value to minimum 0.25 sec.
Number of SD Clock cycles for 0.25sec should be minimum (SD Clock/sec * 0.25 sec) SD Clock cycles = (mmc->tran_speed * 1/4) SD Clock cycles
Calculating timeout based on (2^(timeout + 13)) >= mmc->tran_speed * 1/4 Taking log2 both the sides and rounding up to next power of 2 => timeout + 13 = log2(mmc->tran_speed/4) + 1
Signed-off-by: Priyanka Jain Priyanka.Jain@freescale.com Signed-off-by: Andy Fleming afleming@freescale.com Signed-off-by: Kumar Gala galak@kernel.crashing.org Acked-by: Mingkai Hu Mingkai.Hu@freescale.com
Tested on a i.MX51 board.
Tested-by: Stefano Babic sbabic@denx.de
Best regards, Stefano Babic
thanks
applied.
- k