On 10/04/19 6:19 PM, Tero Kristo wrote: > On 10/04/2019 15:37, Lokesh Vutla wrote: >> Hi Tero, >> >> On 10/04/19 1:34 PM, Tero Kristo wrote: >>> On 10/04/2019 08:37, Lokesh Vutla wrote: >>>> TISCI protocol supports for enabling the device either with exclusive >>>> permissions for the requesting host or with sharing across the hosts. >>>> There are certain devices which are exclusive to Linux context and >>>> there are certain devices that are shared across different host contexts. >>>> So add support for getting this information from DT by increasing >>>> the power-domain cells to 2. >>>> >>>> Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx> >>>> --- >>>> .../devicetree/bindings/soc/ti/sci-pm-domain.txt | 11 +++++++++-- >>>> MAINTAINERS | 1 + >>>> include/dt-bindings/soc/ti,sci_pm_domain.h | 9 +++++++++ >>>> 3 files changed, 19 insertions(+), 2 deletions(-) >>>> create mode 100644 include/dt-bindings/soc/ti,sci_pm_domain.h >>>> >>>> diff --git a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt >>>> b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt >>>> index f7b00a7c0f68..f541d1f776a2 100644 >>>> --- a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt >>>> +++ b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt >>>> @@ -19,8 +19,15 @@ child of the pmmc node. >>>> Required Properties: >>>> -------------------- >>>> - compatible: should be "ti,sci-pm-domain" >>>> -- #power-domain-cells: Must be 1 so that an id can be provided in each >>>> - device node. >>>> +- #power-domain-cells: Can be one of the following: >>>> + 1: Containing the device id of each node >>>> + 2: First entry should be device id >>>> + Second entry should be one of the floowing: >>>> + TI_SCI_PD_EXCLUSIVE: To allow device to be >>>> + exclusively controlled by >>>> + the requesting hosts. >>>> + TI_SCI_PD_SHARED: To allow device to be shared >>>> + by multiple hosts. >>> >>> One thing should be noted on this, the added flag is purely for software >>> configuration, and is not telling us anything about the HW / firmware. Software >> >> I does say about how firmware handles the requested device. > > There is a slight nuance in the wording here. It tells the firmware how to > handle the device, and you can basically use either flag and it will work... > until someone else attempts to use the same device. I recall DT was supposed to > describe the hardware, not to tell us how to use it. Well Ill put it this way. This flag describes that the requested device is a shared device across multiple hosts :) > >> >>> can decide to have the flag either way and it will work. I just wonder if DT is >>> the correct location to have something like this... Expect to have plenty of >>> churn on this by people swapping the permissions around according to their >>> use-case needs. >> >> Do you have any other suggestion to handle shared devices across VMs? > > Well, we should have configuration data available somewhere, but it sounds like > DT might be wrong location for this. Maybe a whitelist of devices that can be > shared somewhere. Maybe under the PD driver itself. Do we have any examples for We will end up creating a separate list for each SoC and it might change per use case. I would not like to go down that road. Thanks and regards, Lokesh > something similar available in the kernel today? > > -Tero > -- > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
