linux-kernel - [PATCH 4.19 003/639] i2c: stm32f7: rework slave

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Date:   Fri, 24 Jan 2020 10:22:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alain Volmat <alain.volmat@...com>,
        Pierre-Yves MORDRET <pierre-yves.mordret@...com>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: [PATCH 4.19 003/639] i2c: stm32f7: rework slave_id allocation

From: Alain Volmat <alain.volmat@...com>

commit 52d3be711e065a97a57c2f2ffba3098748855bd6 upstream.

The IP can handle two slave addresses. One address can either be
7 bits or 10 bits while the other can only be 7 bits.
In order to ensure that a 10 bits address can always be allocated
(assuming there is only one 7 bits address already allocated),
pick up the 7-bits only address slot in priority when performing a 7-bits
address allocation.

Fixes: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support")
Signed-off-by: Alain Volmat <alain.volmat@...com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@...com>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/i2c/busses/i2c-stm32f7.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1252,7 +1252,7 @@ static int stm32f7_i2c_get_free_slave_id
 	 * slave[0] supports 7-bit and 10-bit slave address
 	 * slave[1] supports 7-bit slave address only
 	 */
-	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+	for (i = STM32F7_I2C_MAX_SLAVE - 1; i >= 0; i--) {
 		if (i == 1 && (slave->flags & I2C_CLIENT_PEC))
 			continue;
 		if (!i2c_dev->slave[i]) {