Messages in this thread | | | Subject | Re: [RFC PATCH 0/3] PM / Domains: Add support for devices that require multiple domains | From | Jon Hunter <> | Date | Mon, 31 Oct 2016 10:44:41 +0000 |
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Hi Rajendra,
On 06/10/16 09:43, Rajendra Nayak wrote: > > On 10/06/2016 01:55 PM, Jon Hunter wrote: >> Hi Rajendra, >> >> On 06/10/16 07:04, Rajendra Nayak wrote: >>> >>> On 09/20/2016 03:58 PM, Jon Hunter wrote: >>>> The Tegra124/210 XUSB subsystem (that consists of both host and device >>>> controllers) is partitioned across 3 PM domains which are: >>>> - XUSBA: Superspeed logic (for USB 3.0) >>>> - XUSBB: Device controller >>>> - XUSBC: Host controller >>>> >>>> These power domains are not nested and can be powered-up and down >>>> independently of one another. In practice different scenarios require >>>> different combinations of the power domains, for example: >>>> - Superspeed host: XUSBA and XUSBC >>>> - Superspeed device: XUSBA and XUSBB >>>> >>>> Although it could be possible to logically nest both the XUSBB and XUSBC >>>> domains under the XUSBA, superspeed may not always be used/required and >>>> so this would keep it on unnecessarily. >>> >>> Hey Jon, so does this RFC provide a way to just specify multiple Powerdomains >>> for a device (which then will *all* be powered on/off together) or does >>> it also provide for more granular control of these powerdomains? >> >> Only to specify multiple power-domains for a device and not the later. >> >>> The above statement seems to suggest you would need more granular control >>> of these powerdomains (like keeping XUSBA off in case superspeed it not >>> needed) but I can't seem to figure out how you achieve it with this series. >> >> It is an interesting point but today we have always kept the superspeed >> partition on if the device is configured for superspeed regardless of >> what is actually connected. I will check to see if the h/w would allow >> us to turn it off if a non-superspeed device is in use but I did not >> think so. >> >> Do you have any interesting use-cases that would make use of this or >> require other such enhancements? > > We do have atleast a few devices which need to control multiple power domains, > I will need to look more to see if any of them can be controlled individually. > The downstream code we have models these (powerdomains) as regulators and > the drivers hence have individual control on each (specifying multiple -supply's > in DT)
Were you able to check to see if you need to have individual control for the power-domains?
Cheers Jon
-- nvpublic
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