On Fri, May 26, 2023 at 04:58:26PM +0300, Jarkko Nikula wrote: > On 5/24/23 21:14, David Zheng wrote: > > With IC_INTR_RX_FULL slave interrupt handler reads data in a loop until > > RX FIFO is empty. When testing with the slave-eeprom, each transaction > > has 2 bytes for address/index and 1 byte for value, the address byte > > can be written as data byte due to dropping STOP condition. > > > > In the test below, the master continuously writes to the slave, first 2 > > bytes are index, 3rd byte is value and follow by a STOP condition. > > > > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D1-D1] > > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D2-D2] > > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D3-D3] > > > > Upon receiving STOP condition slave eeprom would reset `idx_write_cnt` so > > next 2 bytes can be treated as buffer index for upcoming transaction. > > Supposedly the slave eeprom buffer would be written as > > > > EEPROM[0x00D1] = 0xD1 > > EEPROM[0x00D2] = 0xD2 > > EEPROM[0x00D3] = 0xD3 > > > > When CPU load is high the slave irq handler may not read fast enough, > > the interrupt status can be seen as 0x204 with both DW_IC_INTR_STOP_DET > > (0x200) and DW_IC_INTR_RX_FULL (0x4) bits. The slave device may see > > the transactions below. > > > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1794 : INTR_STAT=0x204 > > 0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x1790 : INTR_STAT=0x200 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4 > > > > After `D1` is received, read loop continues to read `00` which is the > > first bype of next index. Since STOP condition is ignored by the loop, > > eeprom buffer index increased to `D2` and `00` is written as value. > > > > So the slave eeprom buffer becomes > > > > EEPROM[0x00D1] = 0xD1 > > EEPROM[0x00D2] = 0x00 > > EEPROM[0x00D3] = 0xD3 > > > > The fix is to use `FIRST_DATA_BYTE` (bit 11) in `IC_DATA_CMD` to split > > the transactions. The first index byte in this case would have bit 11 > > set. Check this indication to inject I2C_SLAVE_WRITE_REQUESTED event > > which will reset `idx_write_cnt` in slave eeprom. > > > > Signed-off-by: David Zheng <david.zheng@xxxxxxxxx> Applied to for-current, thanks! Someone maybe has a Fixes tag for it?
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