[v4] Added Standard mode and SMBus support.

[PATCH V4 4/9] i2c: xiic: Add wait for FIFO empty in send_tx

Posted by Manikanta Guntupalli 3 years, 2 months ago

From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>

If the tx_half_empty interrupt comes first instead of tx_empty,
STOP bit is generated even before all the bytes are transmitted
out on the bus.
STOP bit should be sent only after all the bytes in the FIFO are
transmitted out of the FIFO. So wait until FIFO is empty before sending
the STOP bit.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
---
 drivers/i2c/busses/i2c-xiic.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index edc64b79e293..57084696429c 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -436,6 +436,13 @@ static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
 				data |= XIIC_TX_DYN_STOP_MASK;
 			} else {
 				u8 cr;
+				int status;
+
+				/* Wait till FIFO is empty so STOP is sent last */
+				status = xiic_wait_tx_empty(i2c);
+				if (status)
+					return;
+
 				/* Write to CR to stop */
 				cr = xiic_getreg8(i2c, XIIC_CR_REG_OFFSET);
 				xiic_setreg8(i2c, XIIC_CR_REG_OFFSET, cr &
-- 
2.25.1

Re: [PATCH V4 4/9] i2c: xiic: Add wait for FIFO empty in send_tx

Posted by Wolfram Sang 3 years, 2 months ago

On Thu, Feb 02, 2023 at 03:11:33PM +0530, Manikanta Guntupalli wrote:
> From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
> 
> If the tx_half_empty interrupt comes first instead of tx_empty,
> STOP bit is generated even before all the bytes are transmitted
> out on the bus.
> STOP bit should be sent only after all the bytes in the FIFO are
> transmitted out of the FIFO. So wait until FIFO is empty before sending
> the STOP bit.
> 
> Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
> Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
> Acked-by: Michal Simek <michal.simek@amd.com>

Applied to for-next, thanks!