From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Rob Herring <robh@kernel.org>,
baruch@tkos.co.il, kernel@pengutronix.de, a.zummo@towertech.it,
festevam@gmail.com, s.hauer@pengutronix.de,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
linux-imx@nxp.com, miguelborgesdefreitas@gmail.com,
shawnguo@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over
Date: Mon, 27 Jul 2020 16:49:38 +0200 [thread overview]
Message-ID: <20200727144938.GC239143@piout.net> (raw)
In-Reply-To: <20200727094553.GH1551@shell.armlinux.org.uk>
On 27/07/2020 10:45:53+0100, Russell King - ARM Linux admin wrote:
> > This is but this shouldn't be a DT property as it has to be changed
> > dynamically. I'm working on an ioctl interface to change this
> > configuration.
>
> Why does it need to be changed dynamically? If the hardware components
> are not fitted to allow the RTC to be safely used without DSM, then
> why should userspace be able to disable DSM?
For RTCs with a standby mode, you want to be able to return to standby
mode.
That would happen for example after factory flashing in that common use
case:
- the board is manufactured
- Vbackup is installed, the RTC switches to standby mode
- the board is then booted to flash a system, Vprimary is now present,
the RTC switches to DSM.
At this point, if the board is simply shut down, the RTC will start
draining Vbackup before leaving the factory. Instead, we want to be able
to return to standby mode until the final user switches the product on
for the first time.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Rob Herring <robh@kernel.org>,
miguelborgesdefreitas@gmail.com, a.zummo@towertech.it,
baruch@tkos.co.il, shawnguo@kernel.org, s.hauer@pengutronix.de,
kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over
Date: Mon, 27 Jul 2020 16:49:38 +0200 [thread overview]
Message-ID: <20200727144938.GC239143@piout.net> (raw)
In-Reply-To: <20200727094553.GH1551@shell.armlinux.org.uk>
On 27/07/2020 10:45:53+0100, Russell King - ARM Linux admin wrote:
> > This is but this shouldn't be a DT property as it has to be changed
> > dynamically. I'm working on an ioctl interface to change this
> > configuration.
>
> Why does it need to be changed dynamically? If the hardware components
> are not fitted to allow the RTC to be safely used without DSM, then
> why should userspace be able to disable DSM?
For RTCs with a standby mode, you want to be able to return to standby
mode.
That would happen for example after factory flashing in that common use
case:
- the board is manufactured
- Vbackup is installed, the RTC switches to standby mode
- the board is then booted to flash a system, Vprimary is now present,
the RTC switches to DSM.
At this point, if the board is simply shut down, the RTC will start
draining Vbackup before leaving the factory. Instead, we want to be able
to return to standby mode until the final user switches the product on
for the first time.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2020-07-27 14:51 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-19 14:50 [PATCH 0/2] rtc: pcf8523: Make DSM for battery switch-over configurable from DT and enable it for the cubox-i miguelborgesdefreitas
2020-07-19 14:50 ` miguelborgesdefreitas
2020-07-19 14:50 ` [PATCH 1/2] rtc: pcf8523: Make DSM for battery switch-over configurable from DT miguelborgesdefreitas
2020-07-19 14:50 ` miguelborgesdefreitas
2020-07-19 14:50 ` [PATCH 2/2] ARM: dts: imx6qdl-cubox-i: enable DSM for the RTC miguelborgesdefreitas
2020-07-19 14:50 ` miguelborgesdefreitas
2020-07-19 15:00 ` Baruch Siach
2020-07-19 15:00 ` Baruch Siach
2020-07-20 11:23 ` [PATCH v2 0/3] rtc: pcf8523: imx6qdl-cubox-i: Make DSM for battery switch-over configurable from DT and enable it for the cubox-i miguelborgesdefreitas
2020-07-20 11:23 ` miguelborgesdefreitas
2020-07-20 11:23 ` [PATCH v2 1/3] dt-bindings: rtc: pcf8523: add DSM pm option for battery switch-over miguelborgesdefreitas
2020-07-20 11:23 ` miguelborgesdefreitas
2020-07-23 17:49 ` Rob Herring
2020-07-23 17:49 ` Rob Herring
2020-07-23 19:57 ` Alexandre Belloni
2020-07-23 19:57 ` Alexandre Belloni
2020-07-23 20:41 ` Miguel Borges de Freitas
2020-07-23 20:41 ` Miguel Borges de Freitas
2020-07-27 9:19 ` Jon Nettleton
2020-07-27 9:19 ` Jon Nettleton
2020-07-27 9:45 ` Russell King - ARM Linux admin
2020-07-27 9:45 ` Russell King - ARM Linux admin
2020-07-27 13:33 ` Jon Nettleton
2020-07-27 13:33 ` Jon Nettleton
2020-07-27 14:17 ` Russell King - ARM Linux admin
2020-07-27 14:17 ` Russell King - ARM Linux admin
2020-07-27 14:52 ` Jon Nettleton
2020-07-27 14:52 ` Jon Nettleton
2020-07-27 14:49 ` Alexandre Belloni [this message]
2020-07-27 14:49 ` Alexandre Belloni
2020-07-27 15:24 ` Russell King - ARM Linux admin
2020-07-27 15:24 ` Russell King - ARM Linux admin
2020-07-27 15:41 ` Alexandre Belloni
2020-07-27 15:41 ` Alexandre Belloni
2020-07-27 15:43 ` Russell King - ARM Linux admin
2020-07-27 15:43 ` Russell King - ARM Linux admin
2020-07-27 15:55 ` Jon Nettleton
2020-07-27 15:55 ` Jon Nettleton
2020-07-27 16:16 ` Alexandre Belloni
2020-07-27 16:16 ` Alexandre Belloni
2020-07-27 17:04 ` Jon Nettleton
2020-07-27 17:04 ` Jon Nettleton
2020-07-27 17:30 ` Russell King - ARM Linux admin
2020-07-27 17:30 ` Russell King - ARM Linux admin
2020-07-27 21:13 ` Miguel Borges de Freitas
2020-07-27 21:13 ` Miguel Borges de Freitas
2020-08-25 20:08 ` Alexandre Belloni
2020-08-25 20:08 ` Alexandre Belloni
2020-07-20 11:24 ` [PATCH v2 2/3] rtc: pcf8523: Make DSM for battery switch-over configurable from DT miguelborgesdefreitas
2020-07-20 11:24 ` miguelborgesdefreitas
2020-07-20 11:24 ` [PATCH v2 3/3] ARM: dts: imx6qdl-cubox-i: enable DSM for the RTC miguelborgesdefreitas
2020-07-20 11:24 ` miguelborgesdefreitas
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