From: sudeep.holla@arm•com (Sudeep Holla)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM64: juno: add NOR flash to device tree
Date: Tue, 27 Oct 2015 12:33:03 +0000 [thread overview]
Message-ID: <562F6EFF.2030404@arm.com> (raw)
In-Reply-To: <CACRpkdbpD+Kr01hDc7QnL4x_4=A_rnAO+G0CaMce8+5ns+bx2Q@mail.gmail.com>
On 27/10/15 12:22, Linus Walleij wrote:
> On Tue, Oct 27, 2015 at 1:01 PM, Sudeep Holla <sudeep.holla@arm•com> wrote:
>> On 27/10/15 11:55, Linus Walleij wrote:
[...]
>>> Then it is safe to enable NOR flash and AFS in the kernel.
>>
>> *No*, not on Juno. If we need to enable them for other platforms, then
>> we should either disable NOR flash in DT(or even remove it completely
>> whichever is appropriate).
>>
>> Since idle is enable in defconfig and if DT has idle states, then it
>> can't boot for the reason I previously mentioned.
>
> Yeah right I remember that now. Let's say it is safe to enable
> for the tamper-security reason. There may be other reasons
> not to...
>
> If this is about different idle functionalities blocking flash
> access, what we should do is to in Kconfig make it impossible
> to compile in both deep idle states and flash support at the
> same time, as that is how the system really behaves.
>
> I.e do you mean something like this, or am I getting it wrong?
>
But with this you will never enable idle on all VEXPRESS platforms, what
if the issue on Juno is resolved in future silicon. So I prefer DT way
if we have to enable NOR flash in defconfig.
> index 21340e0be73e..07d91776bcfe 100644
> --- a/drivers/cpuidle/Kconfig.arm
> +++ b/drivers/cpuidle/Kconfig.arm
> @@ -4,6 +4,7 @@
> config ARM_CPUIDLE
> bool "Generic ARM/ARM64 CPU idle Driver"
> select DT_IDLE_STATES
> + depends on !(ARCH_VEXPRESS && MTD)
> help
> Select this to enable generic cpuidle driver for ARM.
> It provides a generic idle driver whose idle states are configured
>
> Hiding hardware from the devicetree seems over the top to me,
OK, I agree with you on not hiding. But disabling it seems OK for me as
it's a hardware errata(SROM can't be used and hence NOR is used in warm
reset path)
> it is better to keep the device trees describing the actual hardware
Agreed, but we need a way to specify that it used as alternative for
SROM to workaround the hardware issue and hence not available for Linux.
One way I believe is setting the status as disabled.
--
Regards,
Sudeep
next prev parent reply other threads:[~2015-10-27 12:33 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-15 10:20 [PATCH] ARM64: juno: add NOR flash to device tree Linus Walleij
2015-10-15 11:58 ` Liviu Dudau
2015-10-15 15:20 ` Arnd Bergmann
2015-10-18 9:22 ` Linus Walleij
2015-10-15 15:30 ` Sudeep Holla
2015-10-18 9:25 ` Linus Walleij
2015-10-19 10:17 ` Sudeep Holla
2015-10-19 10:29 ` Mark Rutland
2015-10-19 11:19 ` Linus Walleij
2015-10-19 11:27 ` Leif Lindholm
2015-10-19 21:50 ` Linus Walleij
2015-10-19 11:39 ` Mark Rutland
2015-10-19 14:40 ` Ard Biesheuvel
2015-10-19 21:58 ` Linus Walleij
2015-10-20 14:13 ` Ard Biesheuvel
2015-10-19 21:55 ` Linus Walleij
2015-10-20 11:20 ` Leif Lindholm
[not found] ` <CAD0U-hKZM-A2N_Lpnzwkt0WmAi+kRR=UOEE4Vr2M-iTo9ikkOg@mail.gmail.com>
2015-10-27 11:55 ` Linus Walleij
2015-10-27 12:01 ` Sudeep Holla
2015-10-27 12:22 ` Linus Walleij
2015-10-27 12:33 ` Sudeep Holla [this message]
2015-10-27 21:41 ` Linus Walleij
2015-10-27 12:33 ` Mark Rutland
2015-10-27 12:41 ` Sudeep Holla
2015-10-27 21:43 ` Linus Walleij
2015-10-27 13:20 ` Ryan Harkin
2015-10-19 11:20 ` Leif Lindholm
2015-10-21 11:18 ` Ryan Harkin
2015-10-26 8:41 ` [PATCH] arm64/efi: register UEFI runtime mmio regions as iomem resources Ard Biesheuvel
2015-10-27 12:08 ` Linus Walleij
2015-10-27 12:31 ` Ard Biesheuvel
2015-11-16 12:45 ` Ard Biesheuvel
2015-10-27 11:59 ` [PATCH] ARM64: juno: add NOR flash to device tree Linus Walleij
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=562F6EFF.2030404@arm.com \
--to=sudeep.holla@arm$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox