[PATCH AUTOSEL 4.19 152/167] i2c: at91: disable TXRDY interrupt after sending data

[PATCH AUTOSEL 4.19 152/167] i2c: at91: disable TXRDY interrupt after sending data

[Sasha Levin]

From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

[ Upstream commit d12e3aae160fb26b534c4496b211d6e60a5179ed ]

Driver was not disabling TXRDY interrupt after last TX byte.
This caused interrupt storm until transfer timeouts for slow
or broken device on the bus. The patch fixes the interrupt storm
on my SAMA5D2-based board.

Cc: stable@vger.kernel.org # 5.2.x
[v5.2 introduced file split; the patch should apply to i2c-at91.c before the split]
Fixes: fac368a04048 ("i2c: at91: add new driver")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Tested-by: Raag Jadav <raagjadav@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/i2c-at91.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 3f3e8b3bf5ff9..0998a388d2ed5 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -270,9 +270,11 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
 	writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
 
 	/* send stop when last byte has been written */
-	if (--dev->buf_len == 0)
+	if (--dev->buf_len == 0) {
 		if (!dev->use_alt_cmd)
 			at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+		at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY);
+	}
 
 	dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
 
@@ -690,9 +692,8 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 		} else {
 			at91_twi_write_next_byte(dev);
 			at91_twi_write(dev, AT91_TWI_IER,
-				       AT91_TWI_TXCOMP |
-				       AT91_TWI_NACK |
-				       AT91_TWI_TXRDY);
+				       AT91_TWI_TXCOMP | AT91_TWI_NACK |
+				       (dev->buf_len ? AT91_TWI_TXRDY : 0));
 		}
 	}
 
-- 
2.20.1

[PATCH AUTOSEL 4.19 153/167] i2c: at91: fix clk_offset for sama5d2

[Sasha Levin]

From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

[ Upstream commit b1ac6704493fa14b5dc19eb6b69a73932361a131 ]

In SAMA5D2 datasheet, TWIHS_CWGR register rescription mentions clock
offset of 3 cycles (compared to 4 in eg. SAMA5D3).

Cc: stable@vger.kernel.org # 5.2.x
[needs applying to i2c-at91.c instead for earlier kernels]
Fixes: 0ef6f3213dac ("i2c: at91: add support for new alternative command mode")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/i2c-at91.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 0998a388d2ed5..d51bf536bdf75 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -914,7 +914,7 @@ static struct at91_twi_pdata sama5d4_config = {
 
 static struct at91_twi_pdata sama5d2_config = {
 	.clk_max_div = 7,
-	.clk_offset = 4,
+	.clk_offset = 3,
 	.has_unre_flag = true,
 	.has_alt_cmd = true,
 	.has_hold_field = true,
-- 
2.20.1