- 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>
Acked-by: Mingkai Hu <Mingkai.Hu@freescale.com>
Tested-by: Stefano Babic <sbabic@denx.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
b71ea33699