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rk27xx: Correct comment about i2c divider calculation

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Change-Id: I75605d5bd6f8a3d1f44b63a9f4467ebcdd15267a
This commit is contained in:
Marcin Bukat 2013-04-04 13:06:46 +02:00
parent f8d36b5baa
commit 670af6344e
1 changed files with 8 additions and 7 deletions
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15
firmware/target/arm/rk27xx/i2c-rk27xx.c
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@ -131,13 +131,14 @@ void i2c_init(void)
/* set I2C divider to stay within allowed SCL freq limit
* APBfreq = 50Mhz
* SCLfreq = (APBfreq/5*(I2CCDVR[5:3] + 1) * 2^((I2CCDVR[2:0] + 1))
*/
/* we are driving this slightly above specs
* (6<<3) | (1<<0) 416kHz
* (7<<3) | (1<<0) 357kHz
* (6<<3) | (2<<0) 208kHz
* I2C_div = (I2CCDVR[5:3] + 1) * 2^((I2CCDVR[2:0] + 1))
* SCLfreq = APBfreq/(5*I2C_div)
*
* (5<<3) | (1<<0) 416.7 KHz (above spec)
* (6<<3) | (1<<0) 357.1 kHz
* (7<<3) | (1<<0) 312.4 kHz
* (6<<3) | (2<<0) 178.6 kHz
* (7<<3) | (2<<0) 156.3 kHz
*/
I2C_OPR = (I2C_OPR & ~(0x3F)) | (6<<3) | (1<<0);