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From: Jan Beulich <jbeulich@suse.com>
To: Connor Davis <connojdavis@gmail.com>
Cc: Jann Horn <jannh@google.com>, Lee Jones <lee.jones@linaro.org>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	xen-devel@lists.xenproject.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled
Date: Mon, 17 May 2021 11:32:01 +0200	[thread overview]
Message-ID: <8ccce25a-e3ca-cb30-f6a3-f9243a85a49b@suse.com> (raw)
In-Reply-To: <d160cee9b61c0ec41c2cd5ff9b4e107011d39d8c.1620952511.git.connojdavis@gmail.com>

On 14.05.2021 02:56, Connor Davis wrote:
> Check if the debug capability is enabled in early_xdbc_parse_parameter,
> and if it is, return with an error. This avoids collisions with whatever
> enabled the DbC prior to linux starting.

Doesn't this go too far and prevent use even if firmware (perhaps
mistakenly) left it enabled?

Jan

> Signed-off-by: Connor Davis <connojdavis@gmail.com>
> ---
>  drivers/usb/early/xhci-dbc.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
> index be4ecbabdd58..ca67fddc2d36 100644
> --- a/drivers/usb/early/xhci-dbc.c
> +++ b/drivers/usb/early/xhci-dbc.c
> @@ -642,6 +642,16 @@ int __init early_xdbc_parse_parameter(char *s)
>  	}
>  	xdbc.xdbc_reg = (struct xdbc_regs __iomem *)(xdbc.xhci_base + offset);
>  
> +	if (readl(&xdbc.xdbc_reg->control) & CTRL_DBC_ENABLE) {
> +		pr_notice("xhci debug capability already in use\n");
> +		early_iounmap(xdbc.xhci_base, xdbc.xhci_length);
> +		xdbc.xdbc_reg = NULL;
> +		xdbc.xhci_base = NULL;
> +		xdbc.xhci_length = 0;
> +
> +		return -ENODEV;
> +	}
> +
>  	return 0;
>  }
>  
> 



  parent reply	other threads:[~2021-05-17  9:32 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-14  0:56 [PATCH v2 0/4] Support xen-driven USB3 debug capability Connor Davis
2021-05-14  0:56 ` [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled Connor Davis
2021-05-14  0:56   ` [PATCH v2 2/4] xen: Export dbgp functions when CONFIG_XEN_DOM0 is enabled Connor Davis
2021-05-14 14:06     ` Connor Davis
2021-05-14  0:56   ` [PATCH v2 3/4] usb: dbgp: Fix return values for reset prep and startup Connor Davis
2021-05-14 15:33     ` Boris Ostrovsky
2021-05-17  9:32   ` Jan Beulich [this message]
2021-05-17 13:48     ` [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled Connor Davis
2021-05-17 14:13       ` Jan Beulich
2021-05-17 14:24         ` Connor Davis
2021-05-18 21:50           ` Mathias Nyman
2021-05-14  6:46 ` [PATCH v2 0/4] Support xen-driven USB3 debug capability Greg Kroah-Hartman
2021-05-14 14:07   ` Connor Davis

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