Re: [PATCH v3 1/5] dt-bindings: soc: Add a new binding for the BCM2835 PM node.
From: Stefan Wahren <hidden>
Date: 2018-12-09 12:14:55
Also in:
linux-devicetree, linux-pm, linux-watchdog, lkml
Hi Eric, [add Sebastian]
quoted hunk ↗ jump to hunk
Eric Anholt [off-list ref] hat am 30. November 2018 um 21:27 geschrieben: This binding supersedes the bcm2835-pm-wdt binding which only covered enough to provide a watchdog, but the HW block is actually mostly about power domains. Signed-off-by: Eric Anholt <redacted> --- .../bindings/soc/bcm/brcm,bcm2835-pm.txt | 42 +++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-pm.txtdiff --git a/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-pm.txt b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-pm.txt new file mode 100644 index 000000000000..7818d33a158f --- /dev/null +++ b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-pm.txt@@ -0,0 +1,42 @@ +BCM2835 PM (Power domains, watchdog) + +The PM block controls power domains and some reset lines, and includes +a watchdog timer. This binding supersedes the brcm,bcm2835-pm-wdt +binding which covered some of PM's register range and functionality. + +Required properties: + +- compatible: Should be "brcm,bcm2835-pm" +- reg: Specifies base physical address and size of the two + register ranges ("PM" and "ASYNC_BRIDGE" in that + order) +- clocks: a) v3d: The V3D clock from CPRMAN + b) peri_image: The PERI_IMAGE clock from CPRMAN + c) h264: The H264 clock from CPRMAN + d) isp: The ISP clock from CPRMAN +- #reset-cells: Should be 1. This property follows the reset controller + bindings[1]. +- #power-domain-cells: Should be 1. This property follows the power domain + bindings[2]. + +Optional properties: + +- timeout-sec: Contains the watchdog timeout in seconds + +[1] Documentation/devicetree/bindings/reset/reset.txt +[2] Documentation/devicetree/bindings/power/power_domain.txt +
sorry for my late reply. I hope we can take the opportunity of a new binding to fix an old issue of the bcm2835-wdt driver. The watchdog driver sets the pm_power_off callback without checking for "system-power-controller" property [3]. As a result we can't use another poweroff controller like e.g. gpio-poweroff. In downstream this has been workarounded by an additional devicetree property for the gpio-poweroff driver [4]. But this isn't the right way because the issue is in the bcm2835 watchdog driver not in all the other reset controller.
Suggested pseudo code:
if (!pm_power_off) {
/* Preserve the old behavior of watchdog driver in case of old DTB */
if (!of_device_is_compatible(dev->of.node, "brcm,bcm2835-pm") ||
of_device_is_system_power_controller(dev->of.node))
pm_power_off = bcm2835_power_off;
}
Best regards
Stefan
[3] - https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/power/power-controller.txt
[4] - https://github.com/raspberrypi/linux/commit/f86dcfac0a4e478fee40b5a3729ff1b159ae91ee
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel