[PATCH] [RFC] i2c: imx: make use of format specifier %dE

[PATCH] [RFC] i2c: imx: make use of format specifier %dE

[Uwe Kleine-König]

I created a patch that teaches printk et al to emit a symbolic error
name for an error valued integer[1]. With that applied

	dev_err(&pdev->dev, "can't enable I2C clock, ret=%dE\n", ret);

emits

	... can't enable I2C clock, ret=EIO

if ret is -EIO. Petr Mladek (i.e. one of the printk maintainers) had
concerns if this would be well received and worth the effort. He asked
to present it to a few subsystems. So for now, this patch converting the
i2c-imx driver shouldn't be applied yet but it would be great to get
some feedback about if you think that being able to easily printk (for
example) "EIO" instead of "-5" is a good idea. Would it help you? Do you
think it helps your users?

Thanks
Uwe

[1] https://lkml.org/lkml/2019/8/27/1456
---
 drivers/i2c/busses/i2c-imx.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 15f6cde6452f..359e911cb891 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -289,7 +289,7 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 	if (IS_ERR(dma->chan_tx)) {
 		ret = PTR_ERR(dma->chan_tx);
 		if (ret != -ENODEV && ret != -EPROBE_DEFER)
-			dev_err(dev, "can't request DMA tx channel (%d)\n", ret);
+			dev_err(dev, "can't request DMA tx channel (%dE)\n", ret);
 		goto fail_al;
 	}
 
@@ -300,7 +300,7 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 	dma_sconfig.direction = DMA_MEM_TO_DEV;
 	ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
 	if (ret < 0) {
-		dev_err(dev, "can't configure tx channel (%d)\n", ret);
+		dev_err(dev, "can't configure tx channel (%dE)\n", ret);
 		goto fail_tx;
 	}
 
@@ -308,7 +308,7 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 	if (IS_ERR(dma->chan_rx)) {
 		ret = PTR_ERR(dma->chan_rx);
 		if (ret != -ENODEV && ret != -EPROBE_DEFER)
-			dev_err(dev, "can't request DMA rx channel (%d)\n", ret);
+			dev_err(dev, "can't request DMA rx channel (%dE)\n", ret);
 		goto fail_tx;
 	}
 
@@ -319,7 +319,7 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 	dma_sconfig.direction = DMA_DEV_TO_MEM;
 	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
 	if (ret < 0) {
-		dev_err(dev, "can't configure rx channel (%d)\n", ret);
+		dev_err(dev, "can't configure rx channel (%dE)\n", ret);
 		goto fail_rx;
 	}
 
@@ -964,7 +964,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 	pm_runtime_put_autosuspend(i2c_imx->adapter.dev.parent);
 
 out:
-	dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
+	dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %dE\n", __func__,
 		(result < 0) ? "error" : "success msg",
 			(result < 0) ? result : num);
 	return (result < 0) ? result : num;
@@ -1100,7 +1100,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
 
 	ret = clk_prepare_enable(i2c_imx->clk);
 	if (ret) {
-		dev_err(&pdev->dev, "can't enable I2C clock, ret=%d\n", ret);
+		dev_err(&pdev->dev, "can't enable I2C clock, ret=%dE\n", ret);
 		return ret;
 	}
 
@@ -1108,7 +1108,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
 	ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, IRQF_SHARED,
 				pdev->name, i2c_imx);
 	if (ret) {
-		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
+		dev_err(&pdev->dev, "can't claim irq %dE\n", irq);
 		goto clk_disable;
 	}
 
@@ -1230,7 +1230,7 @@ static int __maybe_unused i2c_imx_runtime_resume(struct device *dev)
 
 	ret = clk_enable(i2c_imx->clk);
 	if (ret)
-		dev_err(dev, "can't enable I2C clock, ret=%d\n", ret);
+		dev_err(dev, "can't enable I2C clock, ret=%dE\n", ret);
 
 	return ret;
 }
-- 
2.23.0

Re: [PATCH] [RFC] i2c: imx: make use of format specifier %dE

[Wolfram Sang]

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On Thu, Aug 29, 2019 at 06:29:05AM +0200, Uwe Kleine-König wrote:
> I created a patch that teaches printk et al to emit a symbolic error
> name for an error valued integer[1]. With that applied
> 
> 	dev_err(&pdev->dev, "can't enable I2C clock, ret=%dE\n", ret);
> 
> emits
> 
> 	... can't enable I2C clock, ret=EIO
> 
> if ret is -EIO. Petr Mladek (i.e. one of the printk maintainers) had
> concerns if this would be well received and worth the effort. He asked
> to present it to a few subsystems. So for now, this patch converting the
> i2c-imx driver shouldn't be applied yet but it would be great to get
> some feedback about if you think that being able to easily printk (for
> example) "EIO" instead of "-5" is a good idea. Would it help you? Do you
> think it helps your users?

Yes, it would help me. And users, too, I am quite sure. For me, if I mix
up two numbers while debugging, I am hunting ghosts for a while until I
realize my mistake. So:

Acked-by: Wolfram Sang <wsa@the-dreams.de>

I think the main drawback is that ERRORCODES in vsprintf.c now need
maintenance, but I think it is worth the effort. I'd be interested in
the overhead in size this causes, but I also think it is worth the
effort. (It could even be compiled out if we have some generic Kconfig
symbol for smaller kernels).

Thanks,

   Wolfram


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Re: [PATCH] [RFC] i2c: imx: make use of format specifier %dE

[Oleksij Rempel]

On 29.08.19 22:39, Wolfram Sang wrote:
> On Thu, Aug 29, 2019 at 06:29:05AM +0200, Uwe Kleine-König wrote:
>> I created a patch that teaches printk et al to emit a symbolic error
>> name for an error valued integer[1]. With that applied
>>
>> 	dev_err(&pdev->dev, "can't enable I2C clock, ret=%dE\n", ret);
>>
>> emits
>>
>> 	... can't enable I2C clock, ret=EIO
>>
>> if ret is -EIO. Petr Mladek (i.e. one of the printk maintainers) had
>> concerns if this would be well received and worth the effort. He asked
>> to present it to a few subsystems. So for now, this patch converting the
>> i2c-imx driver shouldn't be applied yet but it would be great to get
>> some feedback about if you think that being able to easily printk (for
>> example) "EIO" instead of "-5" is a good idea. Would it help you? Do you
>> think it helps your users?
> 
> Yes, it would help me. And users, too, I am quite sure. For me, if I mix
> up two numbers while debugging, I am hunting ghosts for a while until I
> realize my mistake. So:
> 
> Acked-by: Wolfram Sang <wsa@the-dreams.de>
> 
> I think the main drawback is that ERRORCODES in vsprintf.c now need
> maintenance, but I think it is worth the effort. I'd be interested in
> the overhead in size this causes, but I also think it is worth the
> effort. (It could even be compiled out if we have some generic Kconfig
> symbol for smaller kernels).


I like it, at least it will safe me some time.
I tested this patch together with the vprintf patch, so result looks like:
[    0.281843] imx-i2c 21a0000.i2c: can't enable I2C clock, ret=EIO
[    0.281891] imx-i2c: probe of 21a0000.i2c failed with error -5

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

Kind regards,
Oleksij Rempel

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