On Mon, Mar 09, 2020 at 01:38:09AM +0300, Dmitry Osipenko wrote:
> Driver fails to probe with -EPROBE_DEFER if display output isn't ready
> yet. This produces a bit noisy error message in KMSG during kernel's boot
> up on Tegra20 and Tegra30 because RGB output tends to be probed earlier
> than a corresponding voltage regulator driver.
> 
> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/gpu/drm/tegra/dc.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
> index 56d933e81797..d7f2c4654b6b 100644
> --- a/drivers/gpu/drm/tegra/dc.c
> +++ b/drivers/gpu/drm/tegra/dc.c
> @@ -2571,7 +2571,11 @@ static int tegra_dc_probe(struct platform_device *pdev)
>  
>  	err = tegra_dc_rgb_probe(dc);
>  	if (err < 0 && err != -ENODEV) {
> -		dev_err(&pdev->dev, "failed to probe RGB output: %d\n", err);
> +		if (err == -EPROBE_DEFER)
> +			dev_dbg(&pdev->dev, "RGB output probe deferred\n");
> +		else
> +			dev_err(&pdev->dev, "failed to probe RGB output: %d\n",
> +				err);
>  		return err;
>  	}

I'd prefer if we had just a single message and only differentiate on the
kernel message level, something more along these lines:

	if (err < 0 && err != -ENODEV) {
		const char *level = KERN_ERR;

		if (err == -EPROBE_DEFER)
			level = KERN_DEBUG;

		dev_printk(level, dc->dev, "failed to probe RGB output: %d\n",
			   err);
		return err;
	}

Do you mind if I squash that into your patch?

Thierry