linux-kernel - Re: [PATCH 2/2] usb: gadget: aspeed: fixup usb1 device descriptor at init time

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Message-ID: <55e77bcb37ec780094b8d226f89bd5557e30d913.camel@kernel.crashing.org>
Date:   Thu, 20 Feb 2020 12:39:45 +1100
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     rentao.bupt@...il.com, Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Colin Ian King <colin.king@...onical.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-usb@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org,
        taoren@...com
Subject: Re: [PATCH 2/2] usb: gadget: aspeed: fixup usb1 device descriptor
 at init time

On Tue, 2020-02-18 at 15:56 -0800, rentao.bupt@...il.com wrote:
> From: Tao Ren <rentao.bupt@...il.com>
> 
> This patch moves fixup-usb1-device-descriptor logic from get_descriptor
> handler to "ast_vhub_fixup_dev_desc" function so the device descriptor
> is only patched once (at vhub init time).

I don't like this either. We should make ast_vhub_dev_desc and patch a
copy here too. I know today there's only one instance of the vhub in a
given SoC but that might not always be the case.

> Signed-off-by: Tao Ren <rentao.bupt@...il.com>
> ---
>  drivers/usb/gadget/udc/aspeed-vhub/hub.c | 20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/hub.c b/drivers/usb/gadget/udc/aspeed-vhub/hub.c
> index 4e3ef83283a6..b8bf54b12adc 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/hub.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/hub.c
> @@ -76,13 +76,6 @@ static struct usb_device_descriptor ast_vhub_dev_desc = {
>  	.bNumConfigurations	= 1,
>  };
>  
> -/* Patches to the above when forcing USB1 mode */
> -static void ast_vhub_patch_dev_desc_usb1(struct usb_device_descriptor *desc)
> -{
> -	desc->bcdUSB = cpu_to_le16(0x0100);
> -	desc->bDeviceProtocol = 0;
> -}
> -
>  /*
>   * Configuration descriptor: same comments as above
>   * regarding handling USB1 mode.
> @@ -316,10 +309,6 @@ static int ast_vhub_rep_desc(struct ast_vhub_ep *ep,
>  	if (len > dsize)
>  		len = dsize;
>  
> -	/* Patch it if forcing USB1 */
> -	if (desc_type == USB_DT_DEVICE && ep->vhub->force_usb1)
> -		ast_vhub_patch_dev_desc_usb1(ep->buf);
> -
>  	/* Shoot it from the EP buffer */
>  	return ast_vhub_reply(ep, NULL, len);
>  }
> @@ -878,6 +867,15 @@ static void ast_vhub_fixup_dev_desc(struct ast_vhub *vhub)
>  		if (of_str[id])
>  			ast_vhub_str_array[i].s = of_str[id];
>  	}
> +
> +	/*
> +	 * Update USB Release Number and Protocol code if vhub is running
> +	 * at USB 1.x speed.
> +	 */
> +	if (vhub->force_usb1) {
> +		ast_vhub_dev_desc.bcdUSB = cpu_to_le16(0x0100);
> +		ast_vhub_dev_desc.bDeviceProtocol = 0;
> +	}
>  }
>  
>  void ast_vhub_init_hub(struct ast_vhub *vhub)