linux-kernel - Re: [PATCH v2] usb: ehci: handshake CMD_RUN instead of STS

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Message-ID: <20210901164107.GD404634@rowland.harvard.edu>
Date:   Wed, 1 Sep 2021 12:41:07 -0400
From:   Alan Stern <stern@...land.harvard.edu>
To:     neal_liu <neal_liu@...eedtech.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tony Prisk <linux@...sktech.co.nz>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Tao Ren <rentao.bupt@...il.com>, BMC-SW@...eedtech.com
Subject: Re: [PATCH v2] usb: ehci: handshake CMD_RUN instead of STS_HALT

On Wed, Sep 01, 2021 at 11:50:41AM +0800, neal_liu wrote:
> Retitle.
> 
> For Aspeed, HCHalted status depends on not only Run/Stop but also
> ASS/PSS status.
> Handshake CMD_RUN on startup instead.
> 
> Signed-off-by: neal_liu <neal_liu@...eedtech.com>

I'm still a little doubtful about doing this, but if you guys say it works 
for your hardware then I guess it's okay.

Acked-by: Alan Stern <stern@...land.harvard.edu>

> ---
>  drivers/usb/host/ehci-hcd.c      | 11 ++++++++++-
>  drivers/usb/host/ehci-platform.c |  6 ++++++
>  drivers/usb/host/ehci.h          |  1 +
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> index 10b0365f3439..01c022e46aa2 100644
> --- a/drivers/usb/host/ehci-hcd.c
> +++ b/drivers/usb/host/ehci-hcd.c
> @@ -634,7 +634,16 @@ static int ehci_run (struct usb_hcd *hcd)
>  	/* Wait until HC become operational */
>  	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted writes */
>  	msleep(5);
> -	rc = ehci_handshake(ehci, &ehci->regs->status, STS_HALT, 0, 100 * 1000);
> +
> +	/* For Aspeed, STS_HALT also depends on ASS/PSS status.
> +	 * Skip this check on startup.
> +	 */
> +	if (ehci->is_aspeed)
> +		rc = ehci_handshake(ehci, &ehci->regs->command, CMD_RUN,
> +				    1, 100 * 1000);
> +	else
> +		rc = ehci_handshake(ehci, &ehci->regs->status, STS_HALT,
> +				    0, 100 * 1000);
>  
>  	up_write(&ehci_cf_port_reset_rwsem);
>  
> diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
> index c70f2d0b4aaf..c3dc906274d9 100644
> --- a/drivers/usb/host/ehci-platform.c
> +++ b/drivers/usb/host/ehci-platform.c
> @@ -297,6 +297,12 @@ static int ehci_platform_probe(struct platform_device *dev)
>  					  "has-transaction-translator"))
>  			hcd->has_tt = 1;
>  
> +		if (of_device_is_compatible(dev->dev.of_node,
> +					    "aspeed,ast2500-ehci") ||
> +		    of_device_is_compatible(dev->dev.of_node,
> +					    "aspeed,ast2600-ehci"))
> +			ehci->is_aspeed = 1;
> +
>  		if (soc_device_match(quirk_poll_match))
>  			priv->quirk_poll = true;
>  
> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
> index 80bb823aa9fe..fdd073cc053b 100644
> --- a/drivers/usb/host/ehci.h
> +++ b/drivers/usb/host/ehci.h
> @@ -219,6 +219,7 @@ struct ehci_hcd {			/* one per controller */
>  	unsigned		need_oc_pp_cycle:1; /* MPC834X port power */
>  	unsigned		imx28_write_fix:1; /* For Freescale i.MX28 */
>  	unsigned		spurious_oc:1;
> +	unsigned		is_aspeed:1;
>  
>  	/* required for usb32 quirk */
>  	#define OHCI_CTRL_HCFS          (3 << 6)
> -- 
> 2.17.1
>