Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Neal Liu <neal_liu@aspeedtech.com>
To:     Alan Stern <stern@rowland.harvard.edu>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tony Prisk <linux@prisktech.co.nz>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        Tao Ren <rentao.bupt@gmail.com>, BMC-SW <BMC-SW@aspeedtech.com>
Subject: RE: [PATCH] usb: host: ehci: skip STS_HALT check for aspeed platform
Thread-Topic: [PATCH] usb: host: ehci: skip STS_HALT check for aspeed platform
Thread-Index: AQHXmkn/+OFxJTac2UeWzgoF+9FcjKuF6XAAgAiU45A=
Date:   Wed, 1 Sep 2021 02:34:32 +0000
Message-ID: <HK0PR06MB32025ED058C0461FDC5BFBBB80CD9@HK0PR06MB3202.apcprd06.prod.outlook.com>
References: <20210826071525.27651-1-neal_liu@aspeedtech.com>
 <20210826152824.GC228824@rowland.harvard.edu>
In-Reply-To: <20210826152824.GC228824@rowland.harvard.edu>
Accept-Language: en-US
Content-Language: zh-TW
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?EWx/E0aGAqlnQdtIp7EjzPYHV2I4Mp1MiCLOeoYvEP7Ps11Hh1IhKVEJoMrF?=
 =?us-ascii?Q?n5goykJu42BYx/eusduf9UvyHjBZcxWxtsxkbFys17Uyz3Wrrj/5fkc9xdsQ?=
 =?us-ascii?Q?NKS5XJRZqKfeSVLdUTxlmgX+pcNAUwJjglLFz6wO0/9udz6wLYpZaw/n/qsT?=
 =?us-ascii?Q?4tTGBGSYiJ1B32WV0fVpQkROQD+G1oQ7evM3v6Df3Dj+Lip4CZlG0wp09AoN?=
 =?us-ascii?Q?NXvDgTUlUWVpEmNalNdCCoeHMNlXtIULMvZP+MxNRtCH7HkZBpxGr5VePtXw?=
 =?us-ascii?Q?X0ypS92sHOQ40hMeCYc4wu/UlLU1uBwHrn4A8VCb9+bx3sq1oEACD8cwdd0P?=
 =?us-ascii?Q?4fxClRfL7dPDdDs1EIWxSGhzTIsM+qDNLpMagYoG2PwgCfqDh4c9JAYwAS+y?=
 =?us-ascii?Q?iBqGtFHd/MAvfIQGmkkk1saZ6i/efxDoX1E8NPEdoIe8RgX/LRwywls4KtHj?=
 =?us-ascii?Q?ylU2A5esWXvXuVMt9V4p4SwESmIrhQM8UoOYhchQqI7kQQAbbJV03iK4OJmC?=
 =?us-ascii?Q?0EITSvhP0xNgzIzwfioSTuatOUtnCq6JHPP//g+M8tdQr33YG8HmXpOH43VM?=
 =?us-ascii?Q?7ATG0APzefm4sesKyEMQ/H3gNSHWQhXCvDYL83GbApgXShlQWLAEGjEzJmj/?=
 =?us-ascii?Q?CT6lRlrzuLAhDVch+ET0966PHx4YyzIbb8LrVp4HEPxWMi1X+8sW9eB7izI7?=
 =?us-ascii?Q?454mXdl284M9Lh5vcWz4zBrkA5kL46wwe6ogI2EDhXpG+FS3vbIKoDIKBJzh?=
 =?us-ascii?Q?/0nAjYSxNA5HaPFbOV8xaekbO+B5rAh6WsRo22j56ooQTdGTeMHJdTub+5sR?=
 =?us-ascii?Q?T/YGckVgxYUI8zgXL9vWMPoC5BSFKc1FsA4GmMyCfm5JIzQQI3rpyBKhaJvz?=
 =?us-ascii?Q?FebSp1on7+R29628nXMLUiDPGgP2L+xO0jabrMJoCVUAKJ86ADbaqhoJxIEZ?=
 =?us-ascii?Q?xwRglNeCJUYOKnyTjmb14CIt0fmjRDS+kKZWvqMTi6mQICFiWC7zeyHEHX3g?=
 =?us-ascii?Q?her8xoNOlE28u10+WcTKnPYsgVTk13NSoiyhKheEQvD+d5y+YGQvoRYc+ikD?=
 =?us-ascii?Q?pziJteCqHaGFcO43z2JbV7NlhIgRb0d7C6RSvxf29EYX4Ddelk9tgNhJE5Md?=
 =?us-ascii?Q?LPutLVNYvQ3o8Fe1ABUkK+MxbGAyPrmexYUyNDA8uKYk8J23hJq2LylYRRbg?=
 =?us-ascii?Q?ozBQonLkyLZ5B++uzfzk6jAP8yoErjxJ1mB1E9AuLpMCOlZIvcxlaW1XnKeB?=
 =?us-ascii?Q?WXFkxsWQzLmzpaw+i8fTsF3BNDej6TOq7PYLH5TeJktygoe6GqmuLDA+Q+lM?=
 =?us-ascii?Q?VduV18aQiC6LYyPxI6WTeAlJ?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: aspeedtech.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: HK0PR06MB3202.apcprd06.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: a10b3d75-f480-4ffc-c38a-08d96cf107fa
X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Sep 2021 02:34:32.4779
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 43d4aa98-e35b-4575-8939-080e90d5a249
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: pIjmBtFaW39IpiITK0vaEMqo+Gpee2/5dMlh0vifcXoxqLdjdA5JzncNzyw2fBLqdAsqOAoW2lwPASW9aRrz0g==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: HK0PR06MB2419
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> -----Original Message-----
> From: Alan Stern <stern@rowland.harvard.edu>
> Sent: Thursday, August 26, 2021 11:28 PM
> To: Neal Liu <neal_liu@aspeedtech.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Tony Prisk
> <linux@prisktech.co.nz>; linux-usb@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Tao R=
en
> <rentao.bupt@gmail.com>; BMC-SW <BMC-SW@aspeedtech.com>
> Subject: Re: [PATCH] usb: host: ehci: skip STS_HALT check for aspeed plat=
form
>=20
> On Thu, Aug 26, 2021 at 03:15:25PM +0800, neal_liu wrote:
> > STS_HALT also depends on ASS/PSS status for apseed.
> > Skip this check on startup.
> >
> > Signed-off-by: neal_liu <neal_liu@aspeedtech.com>
> > ---
> >  drivers/usb/host/ehci-hcd.c      | 10 +++++++++-
> >  drivers/usb/host/ehci-platform.c |  6 ++++++
> >  drivers/usb/host/ehci.h          |  1 +
> >  3 files changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> > index 10b0365f3439..a539e11502ef 100644
> > --- a/drivers/usb/host/ehci-hcd.c
> > +++ b/drivers/usb/host/ehci-hcd.c
> > @@ -634,7 +634,15 @@ 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 =3D ehci_handshake(ehci, &ehci->regs->status, STS_HALT, 0, 100 * 1=
000);
> > +
> > +	/* For Aspeed, STS_HALT also depends on ASS/PSS status.
> > +	 * Skip this check on startup.
> > +	 */
> > +	if (ehci->is_aspeed)
> > +		rc =3D 0;
> > +	else
> > +		rc =3D ehci_handshake(ehci, &ehci->regs->status, STS_HALT,
> > +				    0, 100 * 1000);
>=20
> You must not do this.  You are assuming the controller will always begin
> operating within 5 ms of the time it is told to start.  What happens if y=
ou are
> wrong?
>=20
> There must be some way for the aspeed controller's host computer to tell
> when the controller has started running.  Find out what it is and use it.
>=20
> Alan Stern

We can check the command RS bit to tell the controller has started running.
I'll sent next patch within this change.
Thanks

-Neal Liu