linux-kernel - Re: [PATCH] usb: hcd.h: construct hub class request conastants from simpler constants

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Message-ID: <20161118100100.GA20048@kroah.com>
Date:   Fri, 18 Nov 2016 11:01:00 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Tal Shorer <tal.shorer@...il.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: hcd.h: construct hub class request conastants from
 simpler constants

On Fri, Nov 18, 2016 at 11:30:18AM +0200, Tal Shorer wrote:
> Currently, each hub class request constant is defined by a line like:
> 
> Where the "magic" number for the high byte is one of 0x20, 0xa0, 0x23,
> 0xa3.

I think your description here is missing something...

> The 0x80 bit that changes inditace USB_DIR_IN, and the 0x03 that
> pops up is the difference between USB_RECIP_DEVICE (0x00) and
> USB_RECIP_OTHER (0x03). The constant 0x20 bit is USB_TYPE_CLASS.
> 
> This patch eliminates those magic numbers by defining a macro to help
> construct these hub class request from simpler constants.
> Note that USB_RT_HUB is defined as (USB_TYPE_CLASS | USB_RECIP_DEVICE)
> and that USB_RT_PORT is defined as (USB_TYPE_CLASS | USB_RECIP_OTHER).
> 
> Signed-off-by: Tal Shorer <tal.shorer@...il.com>
> ---
>  include/linux/usb/hcd.h | 26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
> index 66fc137..2405853 100644
> --- a/include/linux/usb/hcd.h
> +++ b/include/linux/usb/hcd.h
> @@ -566,21 +566,29 @@ extern void usb_ep0_reinit(struct usb_device *);
>  	((USB_DIR_OUT|USB_TYPE_STANDARD|USB_RECIP_INTERFACE)<<8)
>  
>  /* class requests from the USB 2.0 hub spec, table 11-15 */
> +#define HUB_CLASS_REQ(dir, type, request) ((((dir) | (type)) << 8) | (request))
>  /* GetBusState and SetHubDescriptor are optional, omitted */
> -#define ClearHubFeature		(0x2000 | USB_REQ_CLEAR_FEATURE)
> -#define ClearPortFeature	(0x2300 | USB_REQ_CLEAR_FEATURE)
> -#define GetHubDescriptor	(0xa000 | USB_REQ_GET_DESCRIPTOR)
> -#define GetHubStatus		(0xa000 | USB_REQ_GET_STATUS)
> -#define GetPortStatus		(0xa300 | USB_REQ_GET_STATUS)
> -#define SetHubFeature		(0x2000 | USB_REQ_SET_FEATURE)
> -#define SetPortFeature		(0x2300 | USB_REQ_SET_FEATURE)
> +#define ClearHubFeature \
> +	HUB_CLASS_REQ(USB_DIR_OUT, USB_RT_HUB, USB_REQ_CLEAR_FEATURE)
> +#define ClearPortFeature \
> +	HUB_CLASS_REQ(USB_DIR_OUT, USB_RT_PORT, USB_REQ_CLEAR_FEATURE)
> +#define GetHubDescriptor \
> +	HUB_CLASS_REQ(USB_DIR_IN, USB_RT_HUB, USB_REQ_GET_DESCRIPTOR)
> +#define GetHubStatus HUB_CLASS_REQ(USB_DIR_IN, USB_RT_HUB, USB_REQ_GET_STATUS)
> +#define GetPortStatus \
> +	HUB_CLASS_REQ(USB_DIR_IN, USB_RT_PORT, USB_REQ_GET_STATUS)
> +#define SetHubFeature \
> +	HUB_CLASS_REQ(USB_DIR_OUT, USB_RT_HUB, USB_REQ_SET_FEATURE)
> +#define SetPortFeature \
> +	HUB_CLASS_REQ(USB_DIR_OUT, USB_RT_PORT, USB_REQ_SET_FEATURE)

That's a bit harder to read now, right?  Just put them all on one line
please.

>  /*-------------------------------------------------------------------------*/
>  
>  /* class requests from USB 3.1 hub spec, table 10-7 */
> -#define SetHubDepth		(0x2000 | HUB_SET_DEPTH)
> -#define GetPortErrorCount	(0xa300 | HUB_GET_PORT_ERR_COUNT)
> +#define SetHubDepth HUB_CLASS_REQ(USB_DIR_OUT, USB_RT_HUB, HUB_SET_DEPTH)
> +#define GetPortErrorCount \
> +	HUB_CLASS_REQ(USB_DIR_IN, USB_RT_PORT, HUB_GET_PORT_ERR_COUNT)

Same here.

thanks,

greg k-h