Re: [PATCH v2] usb: core: downgrade log severity to info when descriptor unavailable

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Sep 23, 2014 at 07:12:40PM +0000, Scot Doyle wrote:
> According to commit 0cce2eda19923e5e5ccc8b042dec5af87b3ffad0
>     USB: fix LANGID=0 regression
> 
> usb devices are not required to report string descriptors. Since they are
> optional, log an info message instead of an error message.
> 
> Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
> ---
>  drivers/usb/core/message.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> index 0c8a7fc..da2f1f2 100644
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -780,8 +780,12 @@ static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf)
>  	 * deal with strings at all. Set string_langid to -1 in order to
>  	 * prevent any string to be retrieved from the device */
>  	if (err < 0) {
> -		dev_err(&dev->dev, "string descriptor 0 read error: %d\n",
> -					err);
> +		if (err == -EPIPE)
> +			dev_info(&dev->dev,
> +				 "string descriptor 0 read error: -EPIPE\n");
> +		else
> +			dev_err(&dev->dev,
> +				"string descriptor 0 read error: %d\n", err);

What real difference does this patch make?  What would a user do with
-EPIPE?

And USB devices _are_ required to provide a string descriptor if they
provide a string id, so your changelog body doesn't make much sense.  I
suggest rewriting it to say they aren't required to provide a string
descriptor for string "0".

But even then, I don't understand the goal of this patch.

thanks,

greg k-h