From: Oliver Neukum <oneukum@suse.com>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
Rajaram R <rajaram.officemail@gmail.com>,
Felipe Balbi <felipe.balbi@linux.intel.com>,
Mathias Nyman <mathias.nyman@linux.intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Guenter Roeck <linux@roeck-us.net>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [RFC PATCHv2] usb: USB Type-C Connector Class
Date: Wed, 22 Jun 2016 12:08:57 +0200 [thread overview]
Message-ID: <1466590137.12516.5.camel@suse.com> (raw)
In-Reply-To: <20160622093156.GA19856@kuha.fi.intel.com>
On Wed, 2016-06-22 at 12:31 +0300, Heikki Krogerus wrote:
Hi,
> > Now correct me, if I am misreading the spec. I am sure the system
> > will boot unless it needs ridiculous amounts of power, but
> > will we see anything on the screen? As far as I can tell the spec
> > actually says that you cannot enter an alternate mode without having
> > established a power contract.
> > If we really leave entering modes up to user space, we have lost
> > printk before getting into the initrd at the earliest.
>
> With these boards, you will not see anything on the screen that is
> attached to a Type-C connector until the OS has booted to the point
> where it has negotiated the power contract and entered a mode.
>
> If the system has BIOS/FW/EC capable of negotiating the power contract
> and enter a mode, but where we still are expected to take over the
> whole TCPM in OS, I think the connection will be reset.
Think about a DP over type C display with a USB PD power brick on a
daisy chain.
If the host needs more than 15W or more than 5V, a reset is suicide.
And losing earlyprintk hurts a lot.
This means we need USB PD statically in the kernel. And a kernel
based policy that brings up all displays.
Regards
Oliver
next prev parent reply other threads:[~2016-06-22 10:13 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-19 12:44 [RFC PATCHv2] usb: USB Type-C Connector Class Heikki Krogerus
2016-05-19 14:47 ` Oliver Neukum
2016-05-20 11:24 ` Heikki Krogerus
2016-05-20 13:37 ` Oliver Neukum
2016-05-21 5:51 ` Guenter Roeck
2016-05-21 6:43 ` Oliver Neukum
2016-05-22 15:54 ` Guenter Roeck
2016-05-23 5:34 ` Oliver Neukum
2016-05-23 13:27 ` Guenter Roeck
2016-05-23 13:58 ` Oliver Neukum
2016-05-23 14:43 ` Guenter Roeck
2016-05-23 15:55 ` Oliver Neukum
2016-05-23 16:52 ` Guenter Roeck
2016-05-24 10:08 ` Heikki Krogerus
2016-05-24 10:18 ` Oliver Neukum
2016-05-24 11:04 ` Heikki Krogerus
2016-05-19 14:48 ` Oliver Neukum
2016-05-19 15:43 ` Greg KH
2016-05-20 10:58 ` Heikki Krogerus
2016-05-19 17:53 ` Guenter Roeck
2016-05-20 10:47 ` Heikki Krogerus
2016-05-20 17:02 ` Guenter Roeck
2016-05-23 9:23 ` Heikki Krogerus
2016-05-20 14:19 ` Oliver Neukum
2016-05-23 9:57 ` Heikki Krogerus
2016-05-23 11:25 ` Oliver Neukum
2016-05-23 17:09 ` Guenter Roeck
2016-05-24 9:06 ` Oliver Neukum
2016-05-24 9:32 ` Heikki Krogerus
2016-05-24 12:51 ` Oliver Neukum
2016-05-25 11:28 ` Heikki Krogerus
2016-05-25 15:19 ` Guenter Roeck
2016-05-27 7:30 ` Heikki Krogerus
2016-05-24 13:42 ` Guenter Roeck
2016-05-25 11:30 ` Heikki Krogerus
2016-05-25 13:12 ` Guenter Roeck
2016-05-24 19:28 ` Guenter Roeck
2016-05-25 11:51 ` Heikki Krogerus
2016-05-25 13:21 ` Guenter Roeck
2016-05-25 14:04 ` Heikki Krogerus
2016-05-25 14:20 ` Oliver Neukum
2016-05-25 14:59 ` Guenter Roeck
2016-05-27 7:29 ` Heikki Krogerus
2016-05-25 18:35 ` [RFC PATCH] usb: typec: Various API updates and fixes Guenter Roeck
2016-05-27 7:55 ` Heikki Krogerus
2016-05-27 14:06 ` Guenter Roeck
2016-05-30 12:48 ` Heikki Krogerus
2016-05-30 13:19 ` [RFC PATCHv2] usb: USB Type-C Connector Class Heikki Krogerus
2016-05-30 13:59 ` Oliver Neukum
2016-05-31 8:31 ` Heikki Krogerus
2016-05-31 8:48 ` Oliver Neukum
2016-05-31 12:09 ` Heikki Krogerus
2016-05-31 12:43 ` Heikki Krogerus
2016-05-31 17:20 ` Guenter Roeck
2016-06-01 8:23 ` Heikki Krogerus
2016-06-01 8:31 ` Oliver Neukum
2016-06-01 9:04 ` Oliver Neukum
2016-06-01 13:34 ` Guenter Roeck
2016-06-02 6:24 ` Oliver Neukum
2016-06-02 6:37 ` Guenter Roeck
2016-06-02 7:43 ` Oliver Neukum
2016-05-31 17:14 ` Guenter Roeck
2016-06-01 9:26 ` Oliver Neukum
2016-06-01 23:29 ` Guenter Roeck
2016-06-02 6:30 ` Oliver Neukum
2016-06-02 8:27 ` Heikki Krogerus
2016-06-02 10:18 ` Heikki Krogerus
2016-06-02 16:12 ` Guenter Roeck
2016-06-03 13:21 ` Heikki Krogerus
2016-06-03 13:51 ` Guenter Roeck
2016-06-03 15:17 ` Heikki Krogerus
2016-06-03 18:39 ` Guenter Roeck
2016-06-06 13:28 ` Heikki Krogerus
2016-06-06 13:35 ` Oliver Neukum
2016-06-07 8:23 ` Heikki Krogerus
2016-06-07 16:57 ` Guenter Roeck
2016-06-02 8:02 ` Heikki Krogerus
2016-06-03 20:20 ` Pavel Machek
2016-06-06 13:45 ` Heikki Krogerus
2016-06-06 14:41 ` Greg KH
2016-06-07 8:25 ` Heikki Krogerus
2016-06-06 16:02 ` Guenter Roeck
2016-06-10 14:34 ` [RFC PATCHv3] " Heikki Krogerus
2016-06-11 7:05 ` Oliver Neukum
2016-06-11 18:03 ` Guenter Roeck
2016-06-13 7:49 ` Heikki Krogerus
2016-06-13 7:48 ` Heikki Krogerus
2016-06-21 13:08 ` [RFC PATCHv2] " Oliver Neukum
2016-06-21 13:24 ` Guenter Roeck
2016-06-21 19:43 ` Oliver Neukum
2016-06-21 21:37 ` Guenter Roeck
2016-06-21 13:58 ` Heikki Krogerus
2016-06-21 20:43 ` Oliver Neukum
2016-06-22 9:31 ` Heikki Krogerus
2016-06-22 10:08 ` Oliver Neukum [this message]
2016-06-22 11:19 ` Heikki Krogerus
2016-08-07 21:37 ` Pavel Machek
2016-08-08 8:52 ` Oliver Neukum
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