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Subject: Re: Fw: usbcore missing parentheses in USE_NEW_SCHEME
To:     atmgnd <atmgnd@protonmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        USB list <linux-usb@vger.kernel.org>
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From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <ca600d41-d978-d799-a871-ce6e1438a4cc@infradead.org>
Date:   Wed, 1 Jan 2020 08:38:25 -0800
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[adding linux-usb mailing list]

On 1/1/20 6:46 AM, atmgnd wrote:
> I think there is missing parentheses in macro USE_NEW_SCHEME, it should be:
> #define USE_NEW_SCHEME(i, scheme)      ((i) / 2 == (int)(scheme))
> 
> causes a fail wiht "device descriptor read/64, error -110" using my usb drive on vmware using usb 3.0 hub.
> from https://github.com/torvalds/linux/commit/25244227158e1502062041365a439a54cb8fe673#diff-28615d62e1250eadc353d804f49bc6d6
> 
> someone changed USE_NEW_SCHEME, but without parentheses for second parameter. as result. in fuction use_new_scheme when old_scheme_first is 1, use_new_scheme will return 1 always(actullay is should return 0). it also make https://github.com/torvalds/linux/commit/bd0e6c9614b95352eb31d0207df16dc156c527fa#diff-28615d62e1250eadc353d804f49bc6d6 fails.
> 
> I cannot use git send-mail, there some issue with my network provider. patch below, :
> 
> 
> From 85f01b89d050a988f4d9fc78232de47e793c6a7c Mon Sep 17 00:00:00 2001
> From: atmgnd <atmgnd@outlook.com>
> Date: Wed, 1 Jan 2020 21:27:13 +0800
> Subject: [PATCH] usb: hub: missing parentheses in USE_NEW_SCHEME
> 
> accroding to bd0e6c9#diff-28615d62e1250eadc353d804f49bc6d6, will try old enumeration
> scheme first for high speed devices. for example, when a high speed device pluged in,
> line 2720 should expand to 0 at the first time. USE_NEW_SCHEME(0, 0 || 0 || 1) === 0.
> but it wrongly expand to 1(alway expand to 1 for high speed device), and change
> USE_NEW_SCHEME to USE_NEW_SCHEME((i) % 2 == (int)(scheme)) may be better ?
> 
> Signed-off-by: atmgnd <atmgnd@outlook.com>
> ---
>  drivers/usb/core/hub.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index f229ad6952c0..7d17deca7021 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2692,7 +2692,7 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
>  #define SET_ADDRESS_TRIES 2
>  #define GET_DESCRIPTOR_TRIES 2
>  #define SET_CONFIG_TRIES (2 * (use_both_schemes + 1))
> -#define USE_NEW_SCHEME(i, scheme) ((i) / 2 == (int)scheme)
> +#define USE_NEW_SCHEME(i, scheme) ((i) / 2 == (int)(scheme))
> 
>  #define HUB_ROOT_RESET_TIME 60 /* times are in msec */
>  #define HUB_SHORT_RESET_TIME 10
> --
> 2.17.1
> 


-- 
~Randy