Linux-Watchdog Archive on lore.kernel.org
 help / color / Atom feed
From: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
To: Marco Felsch <m.felsch@pengutronix.de>,
	Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Cc: Support Opensource <Support.Opensource@diasemi.com>,
	"wim@linux-watchdog.org" <wim@linux-watchdog.org>,
	"linux@roeck-us.net" <linux@roeck-us.net>,
	"linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>
Subject: RE: [PATCH] watchdog: da9062: add power management ops
Date: Mon, 2 Dec 2019 13:27:39 +0000
Message-ID: <AM5PR1001MB099461A4E8253F74FC11D6E480430@AM5PR1001MB0994.EURPRD10.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20191202130314.dzne7eh2b5sb46c2@pengutronix.de>

Hi Marco,

> > Hmmm. Wouldn't that then be a board specific fix rather than this change?
> > Am concerned relying on software to reenable the watchdog on resume could
> allow
> > for a hang scenario potentially if that code never gets to execute. Other
> > systems shouldn't need this fix, assuming they don't have issues at the HW
> > level, so this this seems like it could be making those systems less robust. If
> > we are to do this at the driver level, maybe this should be an option through DT
> > to help faulty systems, but I'm thinking this shouldn't be default behaviour.
> 
> I don't think that we should rely on the OTP values. Those values are
> set by Dialog, the SoM manufacturers or by the customer itself and the
> time shows that this is error prone too. At least if the customer or the
> SoM manufacturer don't ask the Dialog Support..
> 
> You're right with the (re-)enabling but there are other drivers using
> such an approach.. IMHO it is safer to go this way rather than trust
> the OTP and the PCB layout. I would rather add a dt-compatible to tell
> the driver to do nothing during suspend/resume e.g.:
> 
>     - dlg,use-hw-pm
> 
> or something. Because the user needs to validate the PCB and the OTP
> values.

The thing is the DT FW is supposed to be fairly static so I would rather not
enforce this change on users if they adopt a kernel version with this update in.
I also still think it's safer if the HW does this for us. I would have hoped for
most designs this would be caught in early bring up where it can be rectified
with minimal impact, although I'm guessing that's not the case in your scenario.

> Regards,
>   Marco

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-28 17:19 Marco Felsch
2019-11-28 17:41 ` Guenter Roeck
2019-12-02 10:04 ` Adam Thomson
2019-12-02 10:56   ` Marco Felsch
2019-12-02 11:11     ` Adam Thomson
2019-12-02 13:03       ` Marco Felsch
2019-12-02 13:27         ` Adam Thomson [this message]
2019-12-02 13:38           ` Guenter Roeck
2019-12-02 14:44             ` Marco Felsch
2019-12-02 14:44             ` Adam Thomson
2019-12-02 15:06               ` Marco Felsch
2019-12-02 15:17                 ` Adam Thomson

Reply instructions:

You may reply publically 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=AM5PR1001MB099461A4E8253F74FC11D6E480430@AM5PR1001MB0994.EURPRD10.PROD.OUTLOOK.COM \
    --to=adam.thomson.opensource@diasemi.com \
    --cc=Support.Opensource@diasemi.com \
    --cc=kernel@pengutronix.de \
    --cc=linux-watchdog@vger.kernel.org \
    --cc=linux@roeck-us.net \
    --cc=m.felsch@pengutronix.de \
    --cc=wim@linux-watchdog.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Watchdog Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-watchdog/0 linux-watchdog/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-watchdog linux-watchdog/ https://lore.kernel.org/linux-watchdog \
		linux-watchdog@vger.kernel.org
	public-inbox-index linux-watchdog

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-watchdog


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git