Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1244990

Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion

Show all headers | View raw

On Tue, Oct 06 2015 at 05:35:41 PM, Rob Herring <robherring2@gmail.com> wrote:
> On Tue, Oct 6, 2015 at 3:47 PM, Laura Abbott <labbott@fedoraproject.org> wrote:

[...]

>> +Example:
>> +
>> +       ion {
>> +               compatbile = "linux,ion";
>> +               #address-cells = <1>;
>> +               #size-cells = <0>;
>> +
>> +               ion-system-heap {
>> +                       linux,ion-heap-id = <0>;
>> +                       linux,ion-heap-type = <ION_SYSTEM_HEAP_TYPE>;
>> +                       linux,ion-heap-name = "system";
>
> How does this vary across platforms? Is all of this being pushed down
> to DT, because there is no coordination of this at the kernel ABI
> level across platforms. In other words, why can't heap 0 be hardcoded
> as system heap in the driver. It seems to me any 1 of these 3
> properties could be used to derive the other 2.

The heap-id<->heap-type mapping isn't necessarily 1:1.  As Laura
indicated elsewhere on this thread, a given heap might need to be
contiguous on one platform but not on another.  In that case you just
swap out the heap-type here and there's no need for userspace to change.

The heap-name, OTOH, could be derived from the heap-id, which is what we
hackishly do here [1] and here[2].

[1] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n53
[2] https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.14/tree/drivers/staging/android/ion/msm/msm_ion.c?h=msm-3.14#n398


-Mitch

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Laura Abbott <labbott@fedoraproject.org> - 2015-10-06 22:50 +0200
  Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Rob Herring <robherring2@gmail.com> - 2015-10-07 00:40 +0200
    Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Laura Abbott <laura@labbott.name> - 2015-10-07 01:10 +0200
      Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Andrew <andrew@ncrmnt.org> - 2015-10-07 12:40 +0200
        Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Rob Herring <robherring2@gmail.com> - 2015-10-07 20:40 +0200
          Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Andrew <andrew@ncrmnt.org> - 2015-10-07 21:30 +0200
          Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Laura Abbott <laura@labbott.name> - 2015-10-08 03:50 +0200
    Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Mitchel Humpherys <mitchelh@codeaurora.org> - 2015-10-12 20:40 +0200
      Re: [RFC][PATCH 1/2] WIP: Devicetree bindings for Ion Andrew <andrew@ncrmnt.org> - 2015-10-13 10:30 +0200

csiph-web