linux-kernel - Re: [PATCH 1/3] usb: xhci: add quirk flag for broken PED bits

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Message-ID: <7d09bdad-0618-c579-a9ad-2bac20a5b525@cogentembedded.com>
Date:   Fri, 18 Nov 2016 13:49:39 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Roger Quadros <rogerq@...com>, balbi@...nel.org,
        mathias.nyman@...el.com
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] usb: xhci: add quirk flag for broken PED bits

Hello.

On 11/17/2016 6:01 PM, Roger Quadros wrote:

> From: Felipe Balbi <balbi@...com>
>
> Some devices from Texas Instruments [1] suffer from
> a silicon bug where Port Enabled/Disabled bit
> should not be used to silence an erroneous device.
>
> The bug is so that if port is disabled with PED
> bit, an IRQ for device removal (or attachment)
> will never fire.
>
> Just for the sake of completeness, the actual
> problem lies with SNPS USB IP and this affects
> all known versions up to 3.00a. A separate
> patch will be added to dwc3 to enabled this
> quirk flag if version is <= 3.00a.
>
> [1] - AM572x Silicon Errata http://www.ti.com/lit/er/sprz429j/sprz429j.pdf
> Section i896— USB xHCI Port Disable Feature Does Not Work
>
> Signed-off-by: Felipe Balbi <balbi@...com>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/usb/host/xhci-hub.c | 6 ++++++
>  drivers/usb/host/xhci.h     | 3 +++
>  2 files changed, 9 insertions(+)
>
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index 0ef1690..c3c051d 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -458,6 +458,12 @@ static void xhci_disable_port(struct usb_hcd *hcd, struct xhci_hcd *xhci,
>  		return;
>  	}
>
> +	if (xhci->quirks & XHCI_BROKEN_PORT_PED) {
> +		xhci_dbg(xhci, "Broken Port Enabled/Disabled, ignoring "
> +				"port disable request.\n");

    The messages shouldn't be broken up to facilitate grepping.

[...]
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index f945380..4f724aa 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1656,6 +1656,9 @@ struct xhci_hcd {
>  #define XHCI_SSIC_PORT_UNUSED	(1 << 22)
>  #define XHCI_NO_64BIT_SUPPORT	(1 << 23)
>  #define XHCI_MISSING_CAS	(1 << 24)
> +/* For controller with a broken Port Disable implementation */
> +#define XHCI_BROKEN_PORT_PED    (1 << 21)

    Indent with tabs as above, please.

[...]

MBR, Sergei