From: Felipe Balbi <balbi@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>,
Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org,
Grygorii Strashko <grygorii.strashko@ti.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
linux-usb@vger.kernel.org, Sekhar Nori <nsekhar@ti.com>,
linux-kernel@vger.kernel.org,
David Fisher <david.fisher1@synopsys.com>,
"Thang Q. Nguyen" <tqnguyen@apm.com>,
Alan Stern <stern@rowland.harvard.edu>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev
Date: Thu, 28 Apr 2016 17:27:14 +0300 [thread overview]
Message-ID: <87vb31kdvh.fsf@intel.com> (raw)
In-Reply-To: <2806018.GHhm6tEuKR@wuerfel>
[-- Attachment #1: Type: text/plain, Size: 1989 bytes --]
Hi,
Arnd Bergmann <arnd@arndb.de> writes:
> On Thursday 28 April 2016 15:16:12 Russell King - ARM Linux wrote:
>> On Thu, Apr 28, 2016 at 09:37:08AM +0300, Felipe Balbi wrote:
>> >
>> > Hi,
>> >
>> > Arnd Bergmann <arnd@arndb.de> writes:
>> > > pointer and pass that in platform_data. This is really easy, it's
>> >
>> > Sorry but passing a struct device pointer in platform_data is
>> > ridiculous. Not to mention that, as I said before, we can't assume which
>> > device to pass to xhci_plat in the first place. It might be dwc->dev and
>> > it might be dwc->dev->parent.
>>
>> +1. Passing an unref-counted struct device through platform data is
>> totally mad, Arnd you're off your rocker if you think that's a good
>> idea. What's more is that there's no way to properly refcount the
>> thing.
>
> It's the parent device (or NULL), there is no way it can ever go away as
> it's already refcounted through the device subsystem by the creation
> of the child device.
you're assuming that based on what we have today. We could get into a
situation where we need to use a completely unrelated device and the
problem exists again.
> I do realize that it's a hack, but the idea is to get rid of that
> as soon as possibly by fixing the way the xhci device is probe so
> we no longer need to fake a platform_device as the child here and
> can just use the device itself.
okay, let me try to be extra clear here:
We will *not* remove the extra platform_device because it actually
*does* exist and helps me hide/abstract a bunch of details and make
assumptions about order of certain events. We have already gone through
that in the past when I explained why I wrote dwc3 the way it is; if you
need a refresher, there are mailing list archives for that.
Moreover, this same problem exists for anything under drivers/mfd. It
just so happens that they're usually some i2c or spi device which don't
do DMA by themselves.
--
balbi
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WARNING: multiple messages have this Message-ID (diff)
From: balbi@kernel.org (Felipe Balbi)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev
Date: Thu, 28 Apr 2016 17:27:14 +0300 [thread overview]
Message-ID: <87vb31kdvh.fsf@intel.com> (raw)
In-Reply-To: <2806018.GHhm6tEuKR@wuerfel>
Hi,
Arnd Bergmann <arnd@arndb.de> writes:
> On Thursday 28 April 2016 15:16:12 Russell King - ARM Linux wrote:
>> On Thu, Apr 28, 2016 at 09:37:08AM +0300, Felipe Balbi wrote:
>> >
>> > Hi,
>> >
>> > Arnd Bergmann <arnd@arndb.de> writes:
>> > > pointer and pass that in platform_data. This is really easy, it's
>> >
>> > Sorry but passing a struct device pointer in platform_data is
>> > ridiculous. Not to mention that, as I said before, we can't assume which
>> > device to pass to xhci_plat in the first place. It might be dwc->dev and
>> > it might be dwc->dev->parent.
>>
>> +1. Passing an unref-counted struct device through platform data is
>> totally mad, Arnd you're off your rocker if you think that's a good
>> idea. What's more is that there's no way to properly refcount the
>> thing.
>
> It's the parent device (or NULL), there is no way it can ever go away as
> it's already refcounted through the device subsystem by the creation
> of the child device.
you're assuming that based on what we have today. We could get into a
situation where we need to use a completely unrelated device and the
problem exists again.
> I do realize that it's a hack, but the idea is to get rid of that
> as soon as possibly by fixing the way the xhci device is probe so
> we no longer need to fake a platform_device as the child here and
> can just use the device itself.
okay, let me try to be extra clear here:
We will *not* remove the extra platform_device because it actually
*does* exist and helps me hide/abstract a bunch of details and make
assumptions about order of certain events. We have already gone through
that in the past when I explained why I wrote dwc3 the way it is; if you
need a refresher, there are mailing list archives for that.
Moreover, this same problem exists for anything under drivers/mfd. It
just so happens that they're usually some i2c or spi device which don't
do DMA by themselves.
--
balbi
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next prev parent reply other threads:[~2016-04-28 14:29 UTC|newest]
Thread overview: 182+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-25 19:21 [PATCH] usb: dwc3: host: inherit dma configuration from parent dev Grygorii Strashko
2016-04-25 19:21 ` Grygorii Strashko
2016-04-26 6:17 ` Felipe Balbi
2016-04-26 6:17 ` Felipe Balbi
2016-04-26 8:14 ` Grygorii Strashko
2016-04-26 8:14 ` Grygorii Strashko
2016-04-27 5:41 ` Felipe Balbi
2016-04-27 5:41 ` Felipe Balbi
2016-04-27 11:55 ` Grygorii Strashko
2016-04-27 11:55 ` Grygorii Strashko
2016-04-27 13:59 ` Catalin Marinas
2016-04-27 13:59 ` Catalin Marinas
2016-04-27 14:11 ` Arnd Bergmann
2016-04-27 14:11 ` Arnd Bergmann
2016-04-27 15:50 ` Catalin Marinas
2016-04-27 15:50 ` Catalin Marinas
2016-04-27 16:04 ` Arnd Bergmann
2016-04-27 16:04 ` Arnd Bergmann
2016-04-27 16:53 ` Felipe Balbi
2016-04-27 16:53 ` Felipe Balbi
2016-04-27 17:42 ` Arnd Bergmann
2016-04-27 17:42 ` Arnd Bergmann
2016-04-27 17:59 ` Alan Stern
2016-04-27 17:59 ` Alan Stern
2016-04-27 18:08 ` Arnd Bergmann
2016-04-27 18:08 ` Arnd Bergmann
2016-04-27 20:05 ` Felipe Balbi
2016-04-27 20:05 ` Felipe Balbi
2016-04-27 21:05 ` Arnd Bergmann
2016-04-27 21:05 ` Arnd Bergmann
2016-04-28 6:37 ` Felipe Balbi
2016-04-28 6:37 ` Felipe Balbi
2016-04-28 14:16 ` Russell King - ARM Linux
2016-04-28 14:16 ` Russell King - ARM Linux
2016-04-28 14:23 ` Arnd Bergmann
2016-04-28 14:23 ` Arnd Bergmann
2016-04-28 14:27 ` Felipe Balbi [this message]
2016-04-28 14:27 ` Felipe Balbi
2016-09-01 22:14 ` Leo Li
2016-09-01 22:14 ` Leo Li
2016-09-02 10:43 ` Arnd Bergmann
2016-09-02 10:43 ` Arnd Bergmann
2016-09-02 10:47 ` Russell King - ARM Linux
2016-09-02 10:47 ` Russell King - ARM Linux
2016-09-02 11:08 ` Felipe Balbi
2016-09-02 11:08 ` Felipe Balbi
2016-09-02 14:11 ` Felipe Balbi
2016-09-02 14:11 ` Felipe Balbi
2016-09-02 14:21 ` Alan Stern
2016-09-02 14:21 ` Alan Stern
2016-09-02 15:51 ` Arnd Bergmann
2016-09-02 15:51 ` Arnd Bergmann
2016-09-07 7:17 ` Roger Quadros
2016-09-07 7:17 ` Roger Quadros
2016-09-07 8:29 ` Arnd Bergmann
2016-09-07 8:29 ` Arnd Bergmann
2016-09-07 13:04 ` Roger Quadros
2016-09-07 13:04 ` Roger Quadros
2016-09-07 14:38 ` Arnd Bergmann
2016-09-07 14:38 ` Arnd Bergmann
2016-09-02 16:23 ` Grygorii Strashko
2016-09-02 16:23 ` Grygorii Strashko
2016-09-02 10:53 ` Felipe Balbi
2016-09-02 10:53 ` Felipe Balbi
2016-09-02 11:55 ` Robin Murphy
2016-09-02 11:55 ` Robin Murphy
2016-09-02 12:56 ` Felipe Balbi
2016-09-02 12:56 ` Felipe Balbi
2016-09-02 13:10 ` Arnd Bergmann
2016-09-02 13:10 ` Arnd Bergmann
2016-09-02 22:16 ` Leo Li
2016-09-02 22:16 ` Leo Li
2016-09-05 15:39 ` Arnd Bergmann
2016-09-05 15:39 ` Arnd Bergmann
2016-09-06 6:35 ` Peter Chen
2016-09-06 6:35 ` Peter Chen
2016-09-06 6:40 ` Felipe Balbi
2016-09-06 6:40 ` Felipe Balbi
2016-09-06 10:46 ` Arnd Bergmann
2016-09-06 10:46 ` Arnd Bergmann
2016-09-06 10:50 ` Felipe Balbi
2016-09-06 10:50 ` Felipe Balbi
2016-09-06 13:27 ` Arnd Bergmann
2016-09-06 13:27 ` Arnd Bergmann
2016-09-07 6:51 ` Felipe Balbi
2016-09-07 6:51 ` Felipe Balbi
2016-09-07 7:44 ` Peter Chen
2016-09-07 7:44 ` Peter Chen
2016-09-07 8:52 ` Arnd Bergmann
2016-09-07 8:52 ` Arnd Bergmann
2016-09-07 9:29 ` Peter Chen
2016-09-07 9:29 ` Peter Chen
2016-09-07 9:35 ` Russell King - ARM Linux
2016-09-07 9:35 ` Russell King - ARM Linux
2016-09-07 10:18 ` Felipe Balbi
2016-09-07 10:18 ` Felipe Balbi
2016-09-06 10:38 ` Arnd Bergmann
2016-09-06 10:38 ` Arnd Bergmann
2016-09-07 6:33 ` Peter Chen
2016-09-07 6:33 ` Peter Chen
2016-09-07 8:48 ` Arnd Bergmann
2016-09-07 8:48 ` Arnd Bergmann
2016-09-07 9:55 ` Peter Chen
2016-09-07 9:55 ` Peter Chen
2016-09-07 10:33 ` Robin Murphy
2016-09-07 10:33 ` Robin Murphy
2016-09-07 10:47 ` Felipe Balbi
2016-09-07 10:47 ` Felipe Balbi
2016-09-14 16:31 ` Lorenzo Pieralisi
2016-09-14 16:31 ` Lorenzo Pieralisi
2016-09-14 21:50 ` Arnd Bergmann
2016-09-14 21:50 ` Arnd Bergmann
2016-09-07 10:24 ` Felipe Balbi
2016-09-07 10:24 ` Felipe Balbi
2016-09-07 15:24 ` Arnd Bergmann
2016-09-07 15:24 ` Arnd Bergmann
2016-09-07 16:08 ` Alan Stern
2016-09-07 16:08 ` Alan Stern
2016-09-07 19:45 ` Arnd Bergmann
2016-09-07 19:45 ` Arnd Bergmann
2016-09-08 1:15 ` Peter Chen
2016-09-08 1:15 ` Peter Chen
2016-09-08 8:02 ` Arnd Bergmann
2016-09-08 8:02 ` Arnd Bergmann
2016-09-08 8:03 ` Felipe Balbi
2016-09-08 8:03 ` Felipe Balbi
2016-09-08 8:26 ` Arnd Bergmann
2016-09-08 8:26 ` Arnd Bergmann
2016-09-08 8:29 ` Felipe Balbi
2016-09-08 8:29 ` Felipe Balbi
2016-09-08 8:45 ` Arnd Bergmann
2016-09-08 8:45 ` Arnd Bergmann
2016-09-08 9:43 ` Felipe Balbi
2016-09-08 9:43 ` Felipe Balbi
2016-09-08 10:17 ` Arnd Bergmann
2016-09-08 10:17 ` Arnd Bergmann
2016-09-08 11:00 ` Felipe Balbi
2016-09-08 11:00 ` Felipe Balbi
2016-09-08 11:11 ` Arnd Bergmann
2016-09-08 11:11 ` Arnd Bergmann
2016-09-08 11:20 ` Felipe Balbi
2016-09-08 11:20 ` Felipe Balbi
2016-09-08 11:39 ` Arnd Bergmann
2016-09-08 11:39 ` Arnd Bergmann
2016-09-08 11:52 ` Felipe Balbi
2016-09-08 11:52 ` Felipe Balbi
2016-09-08 12:46 ` Arnd Bergmann
2016-09-08 12:46 ` Arnd Bergmann
2016-09-08 12:02 ` Grygorii Strashko
2016-09-08 12:02 ` Grygorii Strashko
2016-09-08 12:14 ` Arnd Bergmann
2016-09-08 12:14 ` Arnd Bergmann
2016-09-08 12:28 ` Peter Chen
2016-09-08 12:28 ` Peter Chen
2016-09-08 12:52 ` Arnd Bergmann
2016-09-08 12:52 ` Arnd Bergmann
2016-09-09 1:37 ` Peter Chen
2016-09-09 1:37 ` Peter Chen
2016-09-08 12:59 ` Grygorii Strashko
2016-09-08 12:59 ` Grygorii Strashko
2016-09-09 1:52 ` Peter Chen
2016-09-09 1:52 ` Peter Chen
2016-09-21 11:06 ` Sriram Dash
2016-09-21 11:06 ` Sriram Dash
2016-09-21 11:31 ` Arnd Bergmann
2016-09-21 11:31 ` Arnd Bergmann
2016-09-21 11:43 ` Sriram Dash
2016-09-21 11:43 ` Sriram Dash
2016-09-21 12:48 ` Arnd Bergmann
2016-09-21 12:48 ` Arnd Bergmann
2016-09-22 5:02 ` Sriram Dash
2016-09-22 5:02 ` Sriram Dash
2016-10-07 22:46 ` Leo Li
2016-10-07 22:46 ` Leo Li
2016-09-21 17:14 ` [PATCH] usb: xhci: Fix the patch inherit dma configuration from kbuild test robot
2016-09-21 17:14 ` kbuild test robot
2016-04-27 20:57 ` [PATCH] usb: dwc3: host: inherit dma configuration from parent dev Felipe Balbi
2016-04-27 20:57 ` Felipe Balbi
2016-04-27 14:14 ` Grygorii Strashko
2016-04-27 14:14 ` Grygorii Strashko
2016-05-05 17:07 ` Brian Norris
2016-05-05 17:07 ` Brian Norris
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