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From: Marc Zyngier <marc.zyngier@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Timur Tabi <timur@codeaurora.org>
Cc: Ganesh Mahendran <opensource.ganesh@gmail.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	rrichter@cavium.com, tchalamarla@cavium.com,
	Shanker Donthineni <shankerd@codeaurora.org>,
	apinski@cavium.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] Revert "arm64: Increase the max granular size"
Date: Thu, 17 Mar 2016 16:03:08 +0000	[thread overview]
Message-ID: <56EAD53C.80707@arm.com> (raw)
In-Reply-To: <20160317153747.GD11623@e104818-lin.cambridge.arm.com>

On 17/03/16 15:37, Catalin Marinas wrote:
> On Thu, Mar 17, 2016 at 09:49:51AM -0500, Timur Tabi wrote:

[...]

>> Keep in mind that on an ACPI system like ours, the boot loader (UEFI in our
>> case) configures the system extensively.  It does a lot of things that the
>> kernel would normally do on a device tree system.  For example, pin control
>> is handled completely by UEFI.  The kernel does not set the pin muxes or
>> GPIO directions.  That means we don't support dynamic pin muxing.  Before
>> the kernel is booted, the GPIO pins are fixed.
> 
> And that's great. But you are mistaken in thinking that DT requires lots
> of drivers in the kernel and prevents the firmware from doing sane
> stuff. DT rather gained additional features out of necessity since the
> firmware was not always doing a proper job at hardware initialisation.
> A DT-enabled kernel does not impose restrictions on such firmware
> features. With ACPI, the choice is not as wide and forces vendors to
> look into their firmware story from a different angle (until they figure
> the _DSD+PRP0001 out and we end up with DT emulated in ACPI).

Or even worse, perverting the couple of things that were actually OK in
ACPI by inventing a new layer of broken stuff:

http://thread.gmane.org/gmane.linux.ports.arm.msm/17828

Once we've reached that level, _DSD fells all nice and cuddly.

	M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2016-03-17 16:03 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16  9:32 [PATCH] Revert "arm64: Increase the max granular size" Ganesh Mahendran
2016-03-16 10:07 ` Will Deacon
2016-03-16 13:06   ` Timur Tabi
2016-03-16 14:03     ` Mark Rutland
2016-03-16 14:35       ` Will Deacon
2016-03-16 14:54         ` Mark Rutland
2016-03-16 14:18     ` Catalin Marinas
2016-03-16 15:26       ` Timur Tabi
2016-03-17 14:27         ` Catalin Marinas
2016-03-17 14:49           ` Timur Tabi
2016-03-17 15:37             ` Catalin Marinas
2016-03-17 16:03               ` Marc Zyngier [this message]
2016-03-17 18:07           ` Andrew Pinski
2016-03-17 18:34             ` Timur Tabi
2016-03-17 18:37             ` Catalin Marinas
2016-03-18 21:05 ` Chalamarla, Tirumalesh
2016-03-21  1:56   ` Ganesh Mahendran
2016-03-21 17:14   ` Catalin Marinas
2016-03-21 17:23     ` Will Deacon
2016-03-21 17:33       ` Catalin Marinas
2016-03-21 17:39         ` Chalamarla, Tirumalesh
     [not found]     ` <CAPub14-sFgx=oCHzJPb9h9b_V0rbn5UAMDNJ-yTkjhz38JPqMQ@mail.gmail.com>
     [not found]       ` <10fef112-37f1-0a1b-b5af-435acd032f01@codeaurora.org>
2017-04-06  7:22         ` Imran Khan
2017-04-06 15:58           ` Catalin Marinas
2017-04-07  2:06             ` Ganesh Mahendran
2017-04-07  8:59               ` Catalin Marinas
2017-04-12  5:13               ` Imran Khan
2017-04-12 14:00                 ` Chalamarla, Tirumalesh
2017-04-17  7:35                   ` Imran Khan
2017-04-17 10:38                     ` Sunil Kovvuri
2017-04-18 14:48                       ` Catalin Marinas
2017-04-18 17:05                         ` Sunil Kovvuri
2017-04-19 12:01                           ` Catalin Marinas
2017-04-19 13:11                             ` Sunil Kovvuri
2017-04-25  6:42                               ` Ding Tianhong
2017-04-18 18:21                     ` Chalamarla, Tirumalesh
2017-04-11  4:40             ` Jon Masters

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