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From: Benjamin GAIGNARD <benjamin.gaignard@st.com>
To: Greg KH <gregkh@linuxfoundation.org>,
	Linus Walleij <linus.walleij@linaro.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	Grant Likely <grant.likely@arm.com>,
	"robh@kernel.org" <robh@kernel.org>,
	Loic PALLARDY <loic.pallardy@st.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"system-dt@lists.openampproject.org" 
	<system-dt@lists.openampproject.org>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"lkml@metux.net" <lkml@metux.net>,
	"linux-imx@nxp.com" <linux-imx@nxp.com>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"sudeep.holla@arm.com" <sudeep.holla@arm.com>,
	"fabio.estevam@nxp.com" <fabio.estevam@nxp.com>,
	"stefano.stabellini@xilinx.com" <stefano.stabellini@xilinx.com>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 2/7] bus: Introduce firewall controller framework
Date: Sat, 15 Feb 2020 12:41:07 +0000
Message-ID: <409eb745-aab2-86a7-bd3a-9e8e05bed057@st.com> (raw)
In-Reply-To: <20200214214051.GA4192967@kroah.com>


On 2/14/20 10:40 PM, Greg KH wrote:
> On Fri, Feb 14, 2020 at 05:05:07PM +0100, Linus Walleij wrote:
>> On Fri, Jan 31, 2020 at 10:06 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>>
>>> Why do people want to abuse the platform bus so much?  If a device is on
>>> a bus that can have such a controller, then it is on a real bus, use it!
>> I'm not saying it is a good thing, but the reason why it is (ab)used so
>> much can be found in:
>> drivers/of/platform.c
>>
>> TL;DR: struct platform_device is the Device McDeviceFace and
>> platform bus the Bus McBusFace used by the device tree parser since
>> it is slightly to completely unaware of what devices it is actually
>> spawning.
> <snip>
>
> Yeah, great explaination, and I understand.  DT stuff really is ok to be
> on a platform bus, as that's what almost all of them are.
>
> But, when you try to start messing around with things like this
> "firewall" says it is doing, it's then obvious that this really isn't a
> DT like thing, but rather you do have a bus involved with a controller
> so that should be used instead.

Ok but how put in place a new bus while keeping the devices on platform
bus to avoid changing all the drivers ?

>
> Or just filter away the DT stuff so that the kernel never even sees
> those devices, which might just be simplest :)

yes but we lost the possibility to change the firewall configuration at
run time. I do expect to be able to describe in the DT firewall configuration
and to use them at run time. That could allow, for example, to handover
a HW block to the coprocessor when the main core is going to be suspended
to save power.

Benjamin

>
> thanks,
>
> greg k-h

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-28 15:37 [PATCH v2 0/7] Introduce bus " Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 1/7] dt-bindings: bus: Add firewall bindings Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 2/7] bus: Introduce firewall controller framework Benjamin Gaignard
2020-01-28 15:52   ` Greg KH
2020-01-28 16:41     ` Benjamin GAIGNARD
2020-01-28 16:57       ` Greg KH
2020-01-28 20:29         ` Benjamin GAIGNARD
2020-01-29  5:49           ` Greg KH
2020-01-29  9:42           ` Linus Walleij
2020-01-29  9:52             ` Greg KH
2020-01-29 11:17               ` Mark Brown
2020-01-31  8:37                 ` Benjamin GAIGNARD
2020-01-31  9:06                   ` Greg KH
2020-02-14 16:05                     ` Linus Walleij
2020-02-14 21:40                       ` Greg KH
2020-02-15 12:41                         ` Benjamin GAIGNARD [this message]
2020-02-16  7:21                           ` Greg KH
2020-01-28 15:38 ` [PATCH v2 3/7] base: Add calls to firewall controller Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 4/7] dt-bindings: bus: Add STM32 ETZPC " Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 5/7] bus: firewall: Add driver for STM32 ETZPC controller Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 6/7] ARM: dts: stm32: Add firewall node for stm32mp157 SoC Benjamin Gaignard
2020-01-28 15:38 ` [PATCH v2 7/7] ARM: dts: stm32: enable firewall controller node on stm32mp157c-ed1 Benjamin Gaignard
2020-01-28 16:36 ` [PATCH v2 0/7] Introduce bus firewall controller framework Sudeep Holla
2020-01-28 16:46   ` Benjamin GAIGNARD
2020-01-28 17:17     ` Sudeep Holla
2020-01-28 20:06       ` Benjamin GAIGNARD
2020-01-28 22:06         ` Robin Murphy
2020-01-29 13:40           ` Benjamin GAIGNARD
2020-01-31 18:25             ` Robin Murphy
2020-02-03 13:16               ` Benjamin GAIGNARD
2020-01-31 20:51             ` Florian Fainelli
2020-02-03 13:41               ` Benjamin GAIGNARD
2020-01-31 20:48         ` Florian Fainelli
2020-02-02 12:23           ` Mark Brown

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