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From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Mathias Nyman <mathias.nyman@linux.intel.com>,
	Ingo Molnar <mingo@redhat.com>,
	tglx@linutronix.de, linux-usb@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org, Jiri Slaby <jslaby@suse.cz>
Subject: Re: [PATCH v5 1/4] usb: dbc: early driver for xhci debug capability
Date: Wed, 25 Jan 2017 10:57:36 +0100	[thread overview]
Message-ID: <20170125095736.GP6515@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20170125092355.GA24580@gmail.com>

On Wed, Jan 25, 2017 at 10:23:55AM +0100, Ingo Molnar wrote:
> 
> * Lu Baolu <baolu.lu@linux.intel.com> wrote:
> 
> > > Hiding essentially an early udelay() implementation in an early-printk driver is 
> > > ugly and counterproductive.

> Yeah - so could we do this in a more generic fashion, not in the early-printk 
> driver but in core x86 code?

So ideally early_printk() would not depend on udelay() being setup.

In fact, ideally early_printk() wouldn't even use udelay -- this very
much includes its own copy.

Why is udelay() required? Can't the thing simply poll its own register
state to wait for completion?

This all sounds like xdbc cruft is still unreliably garbage..

  reply	other threads:[~2017-01-25  9:57 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-15  6:02 [PATCH v5 0/4] usb: early: add support for early printk through USB3 debug port Lu Baolu
2016-11-15  6:02 ` [PATCH v5 1/4] usb: dbc: early driver for xhci debug capability Lu Baolu
2017-01-19  9:37   ` Ingo Molnar
2017-01-20  2:47     ` Lu Baolu
2017-01-22  9:04       ` Ingo Molnar
2017-01-24  4:44         ` Lu Baolu
2017-01-24  8:20           ` Ingo Molnar
2017-01-25  5:28             ` Lu Baolu
2017-01-25  9:23               ` Ingo Molnar
2017-01-25  9:57                 ` Peter Zijlstra [this message]
2017-01-25 12:27                   ` Lu Baolu
2017-01-25 14:38                     ` Peter Zijlstra
2017-01-25 15:51                       ` Lu Baolu
2017-01-25 16:16                         ` Peter Zijlstra
2017-01-26  3:37                           ` Lu Baolu
2017-01-26  7:19                             ` Ingo Molnar
2017-01-26  7:49                               ` Lu Baolu
2017-01-26  8:17                                 ` Ingo Molnar
2017-01-26 10:28                               ` Peter Zijlstra
2017-01-26 16:01                                 ` Ingo Molnar
2017-01-26 17:39                                   ` Peter Zijlstra
2017-01-27  6:51                                     ` Ingo Molnar
2017-02-09  5:59                               ` Lu Baolu
2017-01-26  7:22                         ` Ingo Molnar
2017-02-09  7:37                           ` Lu Baolu
2017-01-25 12:17                 ` Lu Baolu
2017-01-26  3:26                 ` Lu Baolu
2016-11-15  6:02 ` [PATCH v5 2/4] x86: add support for earlyprintk via USB3 debug port Lu Baolu
2017-01-19  9:38   ` Ingo Molnar
2017-01-20  2:48     ` Lu Baolu
2016-11-15  6:02 ` [PATCH v5 3/4] usb: serial: usb_debug: add support for dbc debug device Lu Baolu
2017-01-19  9:39   ` Ingo Molnar
2017-01-20  2:50     ` Lu Baolu
2016-11-15  6:02 ` [PATCH v5 4/4] usb: doc: add document for USB3 debug port usage Lu Baolu
2017-01-19  9:41   ` Ingo Molnar
2017-01-20  2:53     ` Lu Baolu
2017-01-18  6:20 ` [PATCH v5 0/4] usb: early: add support for early printk through USB3 debug port Lu Baolu
2017-01-19  9:06   ` Greg Kroah-Hartman
2017-01-19  9:09     ` Ingo Molnar
2017-01-19 11:24       ` Mathias Nyman
2017-01-19  9:12 ` Ingo Molnar
2017-01-20  2:56   ` Lu Baolu

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