linux-kernel - RE: [PATCH V6 0/4] mailbox/firmware: imx: support SCU channel type

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Date:   Fri, 13 Mar 2020 07:38:31 +0000
From:   Peng Fan <peng.fan@....com>
To:     Leonard Crestez <leonard.crestez@....com>,
        "jassisinghbrar@...il.com" <jassisinghbrar@...il.com>,
        "o.rempel@...gutronix.de" <o.rempel@...gutronix.de>
CC:     "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        Anson Huang <anson.huang@....com>,
        Aisheng Dong <aisheng.dong@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V6 0/4] mailbox/firmware: imx: support SCU channel type

> Subject: RE: [PATCH V6 0/4] mailbox/firmware: imx: support SCU channel
> type
> 
> Hi Leonard,
> 
> > Subject: Re: [PATCH V6 0/4] mailbox/firmware: imx: support SCU channel
> > type
> >
> > On 2020-03-04 7:55 AM, Peng Fan wrote:
> > > From: Peng Fan <peng.fan@....com>
> > >
> > > V6:
> > >   Add Oleksij's R-b tag
> > >   Patch 3/4, per
> > https://www.kernel.org/doc/Documentation/printk-formats.txt
> > >   should use %zu for printk sizeof
> > >
> > > V5:
> > >   Move imx_mu_dcfg below imx_mu_priv
> > >   Add init hooks to imx_mu_dcfg
> > >   drop __packed __aligned
> > >   Add more debug msg
> > >   code style cleanup
> > >
> > > V4:
> > >   Drop IMX_MU_TYPE_[GENERIC, SCU]
> > >   Pack MU chans init to separate function
> > >   Add separate function for SCU chans init and xlate
> > >   Add santity check to msg hdr.size
> > >   Limit SCU MU chans to 6, TX0/RX0/RXDB[0-3]
> > >
> > > V3:
> > >   Rebase to Shawn's for-next
> > >   Include fsl,imx8-mu-scu compatible
> > >   Per Oleksij's comments, introduce generic tx/rx and added scu mu type
> > >   Check fsl,imx8-mu-scu in firmware driver for fast_ipc
> > >
> > > V2:
> > >   Drop patch 1/3 which added fsl,scu property
> > >   Force to use scu channel type when machine has node compatible
> > "fsl,imx-scu"
> > >   Force imx-scu to use fast_ipc
> > >
> > >   I not found a generic method to make SCFW message generic enough,
> > SCFW
> > >   message is not fixed length including TX and RX. And it use TR0/RR0
> > >   interrupt.
> > >
> > > V1:
> > > Sorry to bind the mailbox/firmware patch together. This is make it
> > > to understand what changed to support using 1 TX and 1 RX channel
> > > for SCFW message.
> > >
> > > Per i.MX8QXP Reference mannual, there are several message using
> > > examples. One of them is:
> > > Passing short messages: Transmit register(s) can be used to pass
> > > short messages from one to four words in length. For example, when a
> > > four-word message is desired, only one of the registers needs to
> > > have its corresponding interrupt enable bit set at the receiver side.
> > >
> > > This patchset is to using this for SCFW message to replace four TX
> > > and four RX method.
> >
> > Tested-by: Leonard Crestez <leonard.crestez@....com>
> >
> 
> Thanks for the test.
> 
> > My stress tests pass on imx8qxp with this patcheset, however
> > performance is not greatly improved. My guess is that this happens
> > because of too many interrupts.
> 
> Might be. Could you share your testcase?
> 
> >
> > Is there really a reason to enable TIE? Spinning on TE bits without
> > any interrupts should be just plain faster.
> 
> I could try to disable TIE and give a try. If performance improves lot, I could
> change to non TX interrupt.

After rethinking about this, we need TX interrupt, otherwise we have to
use TX_POLL which is slower or let the client kick the TX state machine.

Compared with original method, this already reduces to use 1 TX and 1 RX
interrupt. This already good for system.

Thanks,
Peng.

> 
> Oleksij, do you agree?
> 
> Thanks,
> Peng.
> 
> >
> > >
> > > Peng Fan (4):
> > >    dt-bindings: mailbox: imx-mu: add SCU MU support
> > >    mailbox: imx: restructure code to make easy for new MU
> > >    mailbox: imx: add SCU MU support
> > >    firmware: imx-scu: Support one TX and one RX
> > >
> > >   .../devicetree/bindings/mailbox/fsl,mu.txt         |   2 +
> > >   drivers/firmware/imx/imx-scu.c                     |  54 ++++-
> > >   drivers/mailbox/imx-mailbox.c                      | 267
> > +++++++++++++++++----
> > >   3 files changed, 260 insertions(+), 63 deletions(-)
> > >
> > >
> > > base-commit: 770fbb32d34e5d6298cc2be590c9d2fd6069aa17
> > >