[PATCH] i2c: imx: make bus recovery through pinctrl optional

[Li Yang]

Since commit 1c4b6c3bcf30 ("i2c: imx: implement bus recovery") the driver
starts to use gpio/pinctrl to do i2c bus recovery. But pinctrl is not
always available for platforms using this driver such as ls1021a and
ls1043a, and the device tree binding also mentioned this gpio based
recovery mechanism as optional. The patch make it really optional that
the probe function won't bailout when pinctrl is not available and it
won't try to register recovery functions if pinctrl is NULL when the
PINCTRL is not enabled at all.

Signed-off-by: Li Yang <le...@freescale.com>
Cc: Gao Pan <b54...@freescale.com>
---
drivers/i2c/busses/i2c-imx.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 1e4d99d..7813153 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1086,12 +1086,6 @@ static int i2c_imx_probe(struct platform_device *pdev)
return ret;
}

- i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
- if (IS_ERR(i2c_imx->pinctrl)) {
- ret = PTR_ERR(i2c_imx->pinctrl);
- goto clk_disable;
- }
-
/* Request IRQ */
ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, 0,
pdev->name, i2c_imx);
@@ -1125,7 +1119,12 @@ static int i2c_imx_probe(struct platform_device *pdev)
goto clk_disable;
}

- i2c_imx_init_recovery_info(i2c_imx, pdev);
+ /* optional bus recovery feature through pinctrl */
+ i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
+ if (IS_ERR_OR_NULL(i2c_imx->pinctrl))
+ dev_info(&pdev->dev, "can't get pinctrl, bus recovery feature disabled\n");
+ else
+ i2c_imx_init_recovery_info(i2c_imx, pdev);

/* Set up platform driver data */
platform_set_drvdata(pdev, i2c_imx);
--
2.3.3

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[Uwe Kleine-König]

Hello,

I'm pretty sure this is wrong. If pinctrl isn't available
devm_pinctrl_get returns NULL? But AFAIK you must not ignore an error,
so the better thing to do is:

i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);

if (IS_ERR(i2c_imx->pinctrl)) {
ret = PTR_ERR(i2c_imx->pinctrl);
goto errorhandling;
}

if (i2c_imx->pinctrl)
i2c_imx_init_recovery_info(i2c_imx, pdev);
else

dev_info(&pdev->dev, "can't get pinctrl, bus recovery feature disabled\n");

right?

Uwe Kleine-König

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |

[Li Yang]

If CONFIG_PINCTRL is not enabled, the devm_pinctrl_get() will return
NULL directly as defined in the include/linux/pinctrl/consumer.h.

If CONFIG_PINCTRL is enabled because we are using a multi-platform
image but the actual hardware used doesn't have a pinctrl driver or
pinctrl device tree nodes. It is expected that the devm_pinctrl_get()
will return error. But as the pinctrl is only used for bus recovery
which is just an optional function of this driver. We shouldn't
bailout the probe but keep the driver working without the bus recovery
function. As for generic errors like (!dev) or out-of-memory, the
probe will fail elsewhere anyway.

Regards,
Leo

[Uwe Kleine-König]

Hello,

Cc += Linus Walleij, linux-gpio

IMHO you shouldn't ignore -ENOMEM from devm_pinctrl_get but just the
case for "there was no pinctrl specified in dt". Also consider the i2c
driver is loaded before the pinctrl driver and devm_pinctrl_get returns
-EPROBE_DEFER (I assume it does, didn't check), this should be handled.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |

[Li Yang]

On Thu, Nov 19, 2015 at 2:08 AM, Uwe Kleine-König

Make sense. -EPROBE_DEFER should be honored. Maybe it's good to
check the -ENOMEM too. I will send a new version.

Thanks,
Leo

[Li Yang]

Since commit 1c4b6c3bcf30 ("i2c: imx: implement bus recovery") the driver
starts to use gpio/pinctrl to do i2c bus recovery. But pinctrl is not
always available for platforms using this driver such as ls1021a and
ls1043a, and the device tree binding also mentioned this gpio based
recovery mechanism as optional. The patch make it really optional that
the probe function won't bailout when pinctrl is not available and it
won't try to register recovery functions if pinctrl is NULL when the
PINCTRL is not enabled at all.

Signed-off-by: Li Yang <le...@freescale.com>
Cc: Gao Pan <b54...@freescale.com>
---

v2: bailout on -ENOMEM and -EPROBE_DEFER

drivers/i2c/busses/i2c-imx.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 9bb0b05..41289f8 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1087,8 +1087,11 @@ static int i2c_imx_probe(struct platform_device *pdev)
return ret;

}

+ /* optional bus recovery feature through pinctrl */

i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);

- if (IS_ERR(i2c_imx->pinctrl)) {
+ /* bailout on -ENOMEM or -EPROBE_DEFER, continue for other errors */
+ if (PTR_ERR(i2c_imx->pinctrl) == -ENOMEM ||
+ PTR_ERR(i2c_imx->pinctrl) == -EPROBE_DEFER) {
ret = PTR_ERR(i2c_imx->pinctrl);
goto clk_disable;
}
@@ -1126,7 +1129,10 @@ static int i2c_imx_probe(struct platform_device *pdev)

goto clk_disable;
}

- i2c_imx_init_recovery_info(i2c_imx, pdev);

+ if (IS_ERR_OR_NULL(i2c_imx->pinctrl))
+ dev_info(&pdev->dev, "can't get pinctrl, bus recovery feature disabled\n");
+ else
+ i2c_imx_init_recovery_info(i2c_imx, pdev);

/* Set up platform driver data */
platform_set_drvdata(pdev, i2c_imx);
--
2.3.3

[Linus Walleij]

On Fri, Nov 20, 2015 at 10:45 PM, Li Yang <le...@freescale.com> wrote:

> - if (IS_ERR(i2c_imx->pinctrl)) {
> + /* bailout on -ENOMEM or -EPROBE_DEFER, continue for other errors */
> + if (PTR_ERR(i2c_imx->pinctrl) == -ENOMEM ||
> + PTR_ERR(i2c_imx->pinctrl) == -EPROBE_DEFER) {

This is one of the evils of deferred probe: you never know if
something will eventually turn up. It feels wrong to bail out
on deferred probe...

I have no better idea though.
Acked-by

Yours,
Linus Walleij