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

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Date:   Thu, 12 Mar 2020 23:09:35 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     Peng Fan <peng.fan@....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

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>

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.

Is there really a reason to enable TIE? Spinning on TE bits without any 
interrupts should be just plain faster.

> 
> 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
>