linux-kernel - [PATCH] i2c: i2c-stm32f7: rework slave

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Date:   Tue, 15 Oct 2019 15:03:09 +0200
From:   Alain Volmat <alain.volmat@...com>
To:     <wsa@...-dreams.de>, <robh+dt@...nel.org>
CC:     <mark.rutland@....com>, <pierre-yves.mordret@...com>,
        <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
        <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <fabrice.gasnier@...com>
Subject: [PATCH] i2c: i2c-stm32f7: rework slave_id allocation

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: 60d609f3 ("i2c: i2c-stm32f7: Add slave support")

Signed-off-by: Alain Volmat <alain.volmat@...com>
---
 drivers/i2c/busses/i2c-stm32f7.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index d36cf08461f7..cfae01b15243 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -1265,7 +1265,7 @@ static int stm32f7_i2c_get_free_slave_id(struct stm32f7_i2c_dev *i2c_dev,
 	 * 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]) {
-- 
2.7.4