diff options
| author | Priyanka Jain <[email protected]> | 2011-03-03 09:18:56 +0530 |
|---|---|---|
| committer | Kumar Gala <[email protected]> | 2011-03-07 08:49:28 -0600 |
| commit | b71ea33699bb694964929e2cdced80ef794bde69 (patch) | |
| tree | aadaa4c2e5edd0b040c629286fdf16636c736f9d /common | |
| parent | 509e19cab43ba38311749eba5ceebd806116ce38 (diff) | |
fsl_esdhc: Correcting esdhc timeout counter calculation
- 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 <[email protected]>
Signed-off-by: Andy Fleming <[email protected]>
Acked-by: Mingkai Hu <[email protected]>
Tested-by: Stefano Babic <[email protected]>
Signed-off-by: Kumar Gala <[email protected]>
Diffstat (limited to 'common')
0 files changed, 0 insertions, 0 deletions