linux-kernel - Re: [PATCH v2 00/17] Make rpmsg a framework

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Message-ID: <20160912222240.GA28944@linaro.org>
Date:   Mon, 12 Sep 2016 16:22:40 -0600
From:   Lina Iyer <lina.iyer@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>, linux-remoteproc@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 00/17] Make rpmsg a framework

On Mon, Sep 12 2016 at 10:52 -0600, Lina Iyer wrote:
>Hi Bjorn,
>
>On Thu, Sep 01 2016 at 16:28 -0600, Bjorn Andersson wrote:
>>This series splits the virtio rpmsg bus driver into a rpmsg bus and a virtio
>>backend/wireformat.
>>
>>
>>As we discussed the Qualcomm SMD implementation a couple of years back people
>>suggested that I should make it "a rpmsg thingie". With the introduction of the
>>Qualcomm 8996 platform, we must support a variant of the communication
>>mechanism that share many of the characteristics of SMD, but are different
>>enough that it can't be done in a single implementation. As such there is
>>enough benefit to do the necessary work and being able to make SMD a "rpmsg
>>thingie".
>>
>>On-top of this series I have patches to switch the current smd clients over to
>>rpmsg (and by that drop the existing SMD implementation).
>>
>>All this allows me to implement the new backend and reuse all existing SMD
>>drivers with the new mechanism.
>>
>
>RPM Communication has to supported even when IRQs are disabled. The most
>important use of this communication is to set the wake up time for the
>CPU subsystem when all the CPUs are powered off. In addition to that,
>"sleep" votes that are sent by the application processor subsystem to
>allow system to go into deep sleep modes can only be triggered when the
>CPU PM domains are power collapsed, drivers do not have a knowledge of
>when that happens. This has to be done by a platform code that registers
>for CPU PM domain power_off/on callbacks.
>
Ok, my bad. These two cases are not critical for the SoC supported by
this driver. So you are good to go from cpuidle perspective

>Using rpmsg may be nice for RPM SMD communication, but mutexes need to
>go away for this driver to be any useful than bare bones active mode
>resource requests for QCOM SoCs. By not doing that now, we lock
>ourselves out of using this SMD driver in the near future when CPU PM
>domains are available in the kernel with an ability to do system low
>power modes.
>
>I hope you would make rpmsg work in IRQ disabled contexts first before
>porting the SMD driver.
>
>Thanks,
>Lina
>
>>
>>Changes from v1:
>>- Split up the patch moving core code to rpmsg_core into several commits
>>- Dropped the wrapping struct in rpmsg_core and just added the ops to the
>> public API (but hid the implementation details)
>>- Reordered things to reduce the size of the later patches
>>
>>Bjorn Andersson (17):
>> rpmsg: Enable matching devices with drivers based on DT
>> rpmsg: Name rpmsg devices based on channel id
>> rpmsg: rpmsg_send() operations takes rpmsg_endpoint
>> rpmsg: Make rpmsg_create_ept() take channel_info struct
>> rpmsg: Clean up rpmsg device vs channel naming
>> rpmsg: Introduce indirection table for rpmsg_device operations
>> rpmsg: Move rpmsg_device API to new file
>> rpmsg: Indirection table for rpmsg_endpoint operations
>> rpmsg: Move endpoint related interface to rpmsg core
>> rpmsg: Move helper for finding rpmsg devices to core
>> rpmsg: Split off generic tail of create_channel()
>> rpmsg: Split rpmsg core and virtio backend
>> rpmsg: Hide rpmsg indirection tables
>> rpmsg: virtio: Hide vrp pointer from the public API
>> rpmsg: Move virtio specifics from public header
>> rpmsg: Allow callback to return errors
>> rpmsg: Introduce Qualcomm SMD backend
>>
>>drivers/remoteproc/Kconfig          |    4 +-
>>drivers/rpmsg/Kconfig               |   14 +
>>drivers/rpmsg/Makefile              |    4 +-
>>drivers/rpmsg/qcom_smd.c            | 1434 +++++++++++++++++++++++++++++++++++
>>drivers/rpmsg/rpmsg_core.c          |  498 ++++++++++++
>>drivers/rpmsg/rpmsg_internal.h      |   82 ++
>>drivers/rpmsg/virtio_rpmsg_bus.c    |  487 +++++-------
>>include/linux/rpmsg.h               |  246 +-----
>>samples/rpmsg/rpmsg_client_sample.c |   14 +-
>>9 files changed, 2266 insertions(+), 517 deletions(-)
>>create mode 100644 drivers/rpmsg/qcom_smd.c
>>create mode 100644 drivers/rpmsg/rpmsg_core.c
>>create mode 100644 drivers/rpmsg/rpmsg_internal.h
>>
>>-- 
>>2.5.0
>>
>>--
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