From: Jim Quinlan <james.quinlan@broadcom.com>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE"
<bcm-kernel-feedback-list@broadcom.com>,
Jassi Brar <jassisinghbrar@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
open list <linux-kernel@vger.kernel.org>,
"moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 2/2] mailbox: Add Broadcom STB mailbox driver
Date: Wed, 21 Oct 2020 17:38:12 -0400 [thread overview]
Message-ID: <CA+-6iNzS6oL5MKKbxRPi_xjK7F+=1T03RO3_A4skUZ3xJHOC0A@mail.gmail.com> (raw)
In-Reply-To: <20201009163848.5tbl5bmvuoj2de2v@bogus>
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On Fri, Oct 9, 2020 at 12:38 PM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Sat, Sep 19, 2020 at 03:22:30PM -0400, Jim Quinlan wrote:
> > only implements the agent-to-platform channel;
>
> In that case any reason why you can't reuse the existing smc transport
> for SCMI. It was added recently in case you haven't checked the latest
> kernel version(v5.8 or above). Check out for drivers/firmware/arm_scmi/smc.c
> IIUC rather vaguely Florian was cc-ed on those patches.
Hi Sudeep,
Sorry for the delay. As Florian mentioned, we tried to use what
you've submitted but could not because in our system a return does not
indicate the completion of the SCMI operation. It is indicated by an
interrupt. There are a number of reasons for this and some are out of
our control.
>
>
> > we may implement the platform-to-agent channel in the future.
>
> This is not yet support with that transport, it is hard to generalise
> as different vendors have their own solutions there.
>
> > An unusual aspect of this driver is how the completion of an SCMI message
> > is indicated. An SCMI message is initiated with an ARM SMC call, but the
> > return of this call does not indicate the execution or completion of the
> > message. Rather, the message's completion is signaled by an interrupt.
> >
>
> So are these not fast SMC/HVC calls then ? If so we may need some changes
> to that driver. I just rejected multiple message support as we had assumed
> fast smc/hvc.
Yes, we are using fast SMC calls. We don't have multiple message
support either. The disconnect we have with the smc/hvc transport
commit si this:
smc_send_message(...)
{
/* ... */
+ arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+ scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));
In our code the second line is not here but in the interrupt handler.
I don't see any way you can easily change/augment the smc/hvc
transport to accommodate us.
Regards,
Jim
>
>
> --
> Regards,
> Sudeep
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prev parent reply other threads:[~2020-10-21 21:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 19:22 [PATCH v3 0/2] mailbox: Add Broadcom STB mailbox driver Jim Quinlan
2020-09-19 19:22 ` [PATCH v3 1/2] dt-bindings: Add bindings for BrcmSTB SCMI " Jim Quinlan
2020-09-19 19:22 ` [PATCH v3 2/2] mailbox: Add Broadcom STB " Jim Quinlan
2020-09-19 19:31 ` Randy Dunlap
2020-09-19 21:04 ` Jim Quinlan
2020-10-09 16:38 ` Sudeep Holla
2020-10-09 17:03 ` Florian Fainelli
2020-10-21 21:38 ` Jim Quinlan [this message]
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