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risc-v/mpfs: i2c: fix an FPGA known issue

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This fixes the following issue:
  - After sending the address, the driver writes an extra zero

Without this patch, the extra write causes an extra ACK that would
terminate the sequence prematurely. This is observed as data read
corruption.

With this fix, the condition is detected precisely. That being the
case, the sequence is continued with a repeated start, after which
the read continues normally.

Signed-off-by: Eero Nurkkala <eero.nurkkala@offcode.fi>
This commit is contained in:
Eero Nurkkala 2023-05-09 11:23:06 +03:00 • committed by Xiang Xiao
parent a0bde84c9a
commit 53b58b0881
1 changed files with 20 additions and 1 deletions
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21
arch/risc-v/src/mpfs/mpfs_i2c.c
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@ -459,7 +459,26 @@ static int mpfs_i2c_irq(int cpuint, void *context, void *arg)
{
/* Send stop condition */
modifyreg32(MPFS_I2C_CTRL, 0, MPFS_I2C_CTRL_STO_MASK);
if (priv->fpga && (priv->rx_idx == 0 && priv->rx_size > 0))
{
/* This is a known bug: FPGA IP sends data twice after
* sending the address occasionally. Instead of sending
* STOP, send repeated start instead.
*/
modifyreg32(MPFS_I2C_CTRL, MPFS_I2C_CTRL_SI_MASK, 0);
clear_irq = 0u;
modifyreg32(MPFS_I2C_CTRL, 0, MPFS_I2C_CTRL_STA_MASK);
/* Jump to the next message */
priv->msgid++;
}
else
{
modifyreg32(MPFS_I2C_CTRL, 0, MPFS_I2C_CTRL_STO_MASK);
}
priv->status = MPFS_I2C_SUCCESS;
}
break;