[PATCH AUTOSEL 4.9 3/9] i2c: bcm2835: Avoid clock stretching timeouts

[PATCH AUTOSEL 4.9 3/9] i2c: bcm2835: Avoid clock stretching timeouts

[Sasha Levin]

From: Eric Anholt <eric@anholt.net>

[ Upstream commit 9495b9b31abe525ebd93da58de2c88b9f66d3a0e ]

The CLKT register contains at poweron 0x40, which at our typical 100kHz
bus rate means .64ms. But there is no specified limit to how long devices
should be able to stretch the clocks, so just disable the timeout. We
still have a timeout wrapping the entire transfer.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
BugLink: https://github.com/raspberrypi/linux/issues/3064
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/i2c-bcm2835.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index 7ed09865cb4b9..4729c14b75017 100644
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -28,6 +28,11 @@
 #define BCM2835_I2C_FIFO	0x10
 #define BCM2835_I2C_DIV		0x14
 #define BCM2835_I2C_DEL		0x18
+/*
+ * 16-bit field for the number of SCL cycles to wait after rising SCL
+ * before deciding the slave is not responding. 0 disables the
+ * timeout detection.
+ */
 #define BCM2835_I2C_CLKT	0x1c
 
 #define BCM2835_I2C_C_READ	BIT(0)
@@ -313,6 +318,12 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	adap->dev.of_node = pdev->dev.of_node;
 	adap->quirks = &bcm2835_i2c_quirks;
 
+	/*
+	 * Disable the hardware clock stretching timeout. SMBUS
+	 * specifies a limit for how long the device can stretch the
+	 * clock, but core I2C doesn't.
+	 */
+	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_CLKT, 0);
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
 
 	ret = i2c_add_adapter(adap);
-- 
2.34.1

[PATCH AUTOSEL 4.9 8/9] i2c: qup: allow COMPILE_TEST

[Sasha Levin]

From: Wolfram Sang <wsa@kernel.org>

[ Upstream commit 5de717974005fcad2502281e9f82e139ca91f4bb ]

Driver builds fine with COMPILE_TEST. Enable it for wider test coverage
and easier maintenance.

Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/busses/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 759c621a860a9..be4b7b1ad39b6 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -783,7 +783,7 @@ config I2C_PXA_SLAVE
 
 config I2C_QUP
 	tristate "Qualcomm QUP based I2C controller"
-	depends on ARCH_QCOM
+	depends on ARCH_QCOM || COMPILE_TEST
 	help
 	  If you say yes to this option, support will be included for the
 	  built-in I2C interface on the Qualcomm SoCs.
-- 
2.34.1

Re: [PATCH AUTOSEL 4.9 8/9] i2c: qup: allow COMPILE_TEST

[Pavel Machek]

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On Tue 2022-02-22 21:32:59, Sasha Levin wrote:
> From: Wolfram Sang <wsa@kernel.org>
> 
> [ Upstream commit 5de717974005fcad2502281e9f82e139ca91f4bb ]
> 
> Driver builds fine with COMPILE_TEST. Enable it for wider test coverage
> and easier maintenance.

I don't believe this is suitable for stable.

Best regards,
								Pavel
								
> +++ b/drivers/i2c/busses/Kconfig
> @@ -783,7 +783,7 @@ config I2C_PXA_SLAVE
>  
>  config I2C_QUP
>  	tristate "Qualcomm QUP based I2C controller"
> -	depends on ARCH_QCOM
> +	depends on ARCH_QCOM || COMPILE_TEST
>  	help
>  	  If you say yes to this option, support will be included for the
>  	  built-in I2C interface on the Qualcomm SoCs.
> -- 
> 2.34.1

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HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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