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Sender: Corey Minyard <tcminyard@gmail.com>
Date:   Tue, 26 Oct 2021 11:50:09 -0500
From:   Corey Minyard <minyard@acm.org>
To:     Kunkun Li <likunkun@bytedance.com>
Cc:     openipmi-developer@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ipmi: ssif: Add msleep in multipart test
Message-ID: <20211026165009.GD2744412@minyard.net>
Reply-To: minyard@acm.org
References: <20211026025834.82766-1-likunkun@bytedance.com>
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On Tue, Oct 26, 2021 at 10:58:34AM +0800, Kunkun Li wrote:
> During multipart test, cmd(6,7,8) or cmd(6,7,7) will
> be sent continuously.

This is not useful information, we don't have access to your tests, so
this is meaningless to us.

> 
> The pressure test found some BMC systems cannot process
> messages in time, resulting in read_response continues to receive
> error messages from i2c.
> Retry mechanism will takes 10s, and finally set not support
> multipart transmit.
> 
> So, to work around this，add msleep after sending cmd 6 and
> cmd 7 respectively. The problem did not appear again in
> pressure test.

No, you can't slow down everyone because you have one dodgy BMC.  You
need to detect that this is a BMC that has the problem and only do it
for those BMCs.

-corey

> 
> Signed-off-by: Kunkun Li <likunkun@bytedance.com>
> ---
>  drivers/char/ipmi/ipmi_ssif.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 20d5af92966d..65841798fafe 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1453,6 +1453,7 @@ static int start_multipart_test(struct i2c_client *client,
>  	ret = i2c_smbus_write_block_data(client,
>  					 SSIF_IPMI_MULTI_PART_REQUEST_START,
>  					 32, msg);
> +	msleep(SSIF_MSG_MSEC);
>  	if (ret) {
>  		retry_cnt--;
>  		if (retry_cnt > 0)
> @@ -1467,6 +1468,7 @@ static int start_multipart_test(struct i2c_client *client,
>  	ret = i2c_smbus_write_block_data(client,
>  					 SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
>  					 32, msg + 32);
> +	msleep(SSIF_MSG_MSEC);
>  	if (ret) {
>  		dev_err(&client->dev, "Could not write multi-part middle, though the BMC said it could handle it.  Just limit sends to one part.\n");
>  		return ret;
> -- 
> 2.11.0
>