From: Wolfgang Grandegger <wg@grandegger.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] ehci: speed up initialization
Date: Mon, 19 Dec 2011 14:31:38 +0100 [thread overview]
Message-ID: <4EEF3CBA.5080404@grandegger.com> (raw)
In-Reply-To: <CAP_ceTwj1OhZG2ds+kk36tyV+NMun7CVLksz-JRqO2C0u+Jfsw@mail.gmail.com>
On 12/19/2011 01:51 PM, Vincent Palatin wrote:
> On Mon, Dec 19, 2011 at 04:07, Wolfgang Grandegger <wg@grandegger.com> wrote:
>> I just realized that this patch breaks "usb start" on my mx53loco board:
>>
>> MX53LOCO U-Boot > usb start
>> (Re)start USB...
>> USB: Register 10011 NbrPorts 1
>> USB EHCI 1.00
>> scanning bus for devices... 1 USB Device(s) found
>> scanning bus for storage devices... 0 Storage Device(s) found
>> scanning bus for ethernet devices... 0 Ethernet Device(s) found
>>
>> MX53LOCO U-Boot > usb start
>> (Re)start USB...
>> USB: Register 10011 NbrPorts 1
>> USB EHCI 1.00
>> scanning bus for devices... 2 USB Device(s) found
>> scanning bus for storage devices... 0 Storage Device(s) found
>> scanning bus for ethernet devices... 1 Ethernet Device(s) found
>>
>> The device is not found at the first attempt. Obviously, a value of 10
>> for bPwrOn2PwrGood seems too short but 20 works fine. Would that be a
>> resonable compromise? If yes, I could send a patch.
>
> This doesn't match the EHCI standard which explicity states that the
> power should be good after 20ms (paragraph 2.3.9 in EHCI 1.0), so we
> should probably find whether we are missing another delay somewhere in
> the generic EHCI code (which used to be hidden and should be fixed) or
> if i.MX53 is not compliant with the standard and need a special quirk.
I'm not an USB expert but if I look into the hub_power_on() function of
the Linux kernel it waits at least 100ms (and only once). See:
http://lxr.linux.no/#linux+v3.1.5/drivers/usb/core/hub.c#L567
Wolfgang.
next prev parent reply other threads:[~2011-12-19 13:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-05 22:52 [U-Boot] [PATCH] ehci: speed up initialization Vincent Palatin
2011-12-10 16:29 ` Remy Bohmer
2011-12-19 12:07 ` Wolfgang Grandegger
2011-12-19 12:51 ` Vincent Palatin
2011-12-19 13:31 ` Wolfgang Grandegger [this message]
2011-12-19 16:59 ` Remy Bohmer
2011-12-19 18:18 ` Vincent Palatin
2011-12-20 16:10 ` Wolfgang Grandegger
2011-12-19 15:32 ` Wolfgang Denk
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