Re: [PATCH 11/14] drivers: firmware: psci: Allow OS Initiated suspend mode

[Lina Iyer <lina.iyer@linaro.org>]

On Fri, Jun 24 2016 at 22:25 -0600, Vikas Sajjan wrote:
>Hi Lina,
>
>On Thu, Jun 23, 2016 at 1:06 AM, Lina Iyer <lina.iyer@linaro.org> wrote:
>> PSCI firmware v1.0 onwards may support 2 different modes for
>> CPU_SUSPEND. Platform coordinated mode is the default and every firmware
>> should support it. OS Initiated mode is optional for the firmware to
>> implement and allow Linux to make an better decision on the state of
>> the CPU cluster heirarchy.
>>
>> With the kernel capable of deciding the state for CPU cluster and
>> coherency domains, the OS Initiated mode may now be used by the kernel,
>> provided the firmware supports it. SET_SUSPEND_MODE is a PSCI function
>> available on v1.0 onwards and can be used to set the mode in the
>> firmware.
>>
>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
>> [Ulf: Rebased on 4.7 rc1]
>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>> ---
>>  drivers/firmware/psci.c   | 22 +++++++++++++++++++++-
>>  include/uapi/linux/psci.h |  5 +++++
>>  2 files changed, 26 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
>> index 03e0458..3920aba 100644
>> --- a/drivers/firmware/psci.c
>> +++ b/drivers/firmware/psci.c
>> @@ -52,6 +52,7 @@
>>   * require cooperation with a Trusted OS driver.
>>   */
>>  static int resident_cpu = -1;
>> +static bool psci_has_osi_pd;
>>
>>  bool psci_tos_resident_on(int cpu)
>>  {
>> @@ -563,10 +564,29 @@ out_put_node:
>>         return err;
>>  }
>>
>> +static int __init psci_1_0_init(struct device_node *np)
>> +{
>> +       int ret;
>> +
>> +       ret = psci_0_2_init(np);
>> +       if (ret)
>> +               return ret;
>> +
>> +       /* Check if PSCI OSI mode is available */
>> +       ret = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
>> +       if (ret & PSCI_1_0_OS_INITIATED) {
>> +               ret = psci_features(PSCI_1_0_FN_SET_SUSPEND_MODE);
>> +               if (!ret)
>> +                       psci_has_osi_pd = true;
>
>IMHO, its better to have this done in psci_init_cpu_suspend() itself
>for 2 reasons
>
>a] psci_init_cpu_suspend() already calls
>psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND])
>b] by moving this in psci_init_cpu_suspend() we make this support
>available even for ACPI platforms, since psci_acpi_init() calls
>psci_probe() and this calls  psci_init_cpu_suspend() for
>PSCI_VERSION_MAJOR(ver) >= 1
>
Hmmm.. I can do that.

Thanks,
Lina



>I even posted a patch [1] yesterday, without being aware of your
>patchset for the same.
>
>[1] http://www.spinics.net/lists/arm-kernel/msg513682.html
>
>
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>>  static const struct of_device_id psci_of_match[] __initconst = {
>>         { .compatible = "arm,psci",     .data = psci_0_1_init},
>>         { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
>> -       { .compatible = "arm,psci-1.0", .data = psci_0_2_init},
>> +       { .compatible = "arm,psci-1.0", .data = psci_1_0_init},
>>         {},
>>  };
>>
>> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
>> index 3d7a0fc..7dd778e 100644
>> --- a/include/uapi/linux/psci.h
>> +++ b/include/uapi/linux/psci.h
>> @@ -48,6 +48,7 @@
>>
>>  #define PSCI_1_0_FN_PSCI_FEATURES              PSCI_0_2_FN(10)
>>  #define PSCI_1_0_FN_SYSTEM_SUSPEND             PSCI_0_2_FN(14)
>> +#define PSCI_1_0_FN_SET_SUSPEND_MODE           PSCI_0_2_FN(15)
>>
>>  #define PSCI_1_0_FN64_SYSTEM_SUSPEND           PSCI_0_2_FN64(14)
>>
>> @@ -93,6 +94,10 @@
>>  #define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK  \
>>                         (0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
>>
>> +#define PSCI_1_0_OS_INITIATED                  BIT(0)
>> +#define PSCI_1_0_SUSPEND_MODE_PC               0
>> +#define PSCI_1_0_SUSPEND_MODE_OSI              1
>> +
>>  /* PSCI return values (inclusive of all PSCI versions) */
>>  #define PSCI_RET_SUCCESS                       0
>>  #define PSCI_RET_NOT_SUPPORTED                 -1
>> --
>> 2.7.4
>>
>>
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