linux-kernel - Re: [PATCH v3] ipmi: update ssif max_xmit_msg

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Date:   Mon, 30 Jul 2018 07:56:02 -0500
From:   Corey Minyard <minyard@....org>
To:     Kamlakant Patel <kamlakant.patel@...ium.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org,
        George Cherian <george.cherian@...ium.com>,
        jayachandran.nair@...ium.com
Subject: Re: [PATCH v3] ipmi: update ssif max_xmit_msg_size limit for
 multi-part messages

On 07/30/2018 05:51 AM, Kamlakant Patel wrote:
> Currently, by setting the xmit_msg_size to 63, the ssif driver never
> does a SSIF_MULTI_n_PART, it falls back to only SSIF_MULTI_2_PART.
> Due to this all IPMI commands with request size more than 63 bytes
> will not work.
>
> As per IPMI spec 2.0 (section 12.15, Table 10), SSIF supports message
> length up to 255 bytes. In a multi-part message, the first part must
> carry 32 bytes with command 06h. All intermediate ("middle") parts must
> carry 32 bytes with command 07h and the number of message data bytes in
> the End transaction can range from 1 to 32 bytes with command 08h.
>
> Update ssif max_xmit_msg_size to handle multi-part messages up
> to 255 bytes.
> Enable command(08h) for End part transaction.

You don't think it's a good idea to test what the BMC is capable of 
doing, per
the patch I sent you earlier?

-corey

> Signed-off-by: Kamlakant Patel <kamlakant.patel@...ium.com>
> Suggested-by: Robert Richter <robert.richter@...ium.com>
> Reported-by: Karthikeyan M <karthikeyanm@...india.co.in>
> ---
>   drivers/char/ipmi/ipmi_ssif.c | 38 +++++++++++++++++++++++++++-----------
>   1 file changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 18e4650..ada59b7 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -60,6 +60,7 @@
>   #define	SSIF_IPMI_REQUEST			2
>   #define	SSIF_IPMI_MULTI_PART_REQUEST_START	6
>   #define	SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE	7
> +#define	SSIF_IPMI_MULTI_PART_REQUEST_END	8
>   #define	SSIF_IPMI_RESPONSE			3
>   #define	SSIF_IPMI_MULTI_PART_RESPONSE_MIDDLE	9
>   
> @@ -88,6 +89,8 @@
>   #define SSIF_MSG_JIFFIES	((SSIF_MSG_USEC * 1000) / TICK_NSEC)
>   #define SSIF_MSG_PART_JIFFIES	((SSIF_MSG_PART_USEC * 1000) / TICK_NSEC)
>   
> +#define SSIF_MAX_MSG_LENGTH	255
> +
>   enum ssif_intf_state {
>   	SSIF_NORMAL,
>   	SSIF_GETTING_FLAGS,
> @@ -887,28 +890,39 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result,
>   		 */
>   		int left;
>   		unsigned char *data_to_send;
> +		int command;
>   
>   		ssif_inc_stat(ssif_info, sent_messages_parts);
>   
>   		left = ssif_info->multi_len - ssif_info->multi_pos;
> -		if (left > 32)
> -			left = 32;
> +
>   		/* Length byte. */
> -		ssif_info->multi_data[ssif_info->multi_pos] = left;
> +		ssif_info->multi_data[ssif_info->multi_pos] =
> +						left > 32 ? 32 : left;
>   		data_to_send = ssif_info->multi_data + ssif_info->multi_pos;
> -		ssif_info->multi_pos += left;
> -		if (left < 32)
> +		ssif_info->multi_pos += left > 32 ? 32 : left;
> +		command = SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE;
> +		if (left <= 32) {
>   			/*
>   			 * Write is finished.  Note that we must end
> -			 * with a write of less than 32 bytes to
> -			 * complete the transaction, even if it is
> -			 * zero bytes.
> +			 * with a write up to 32 bytes to complete the
> +			 * transaction, even if it is zero bytes.
> +			 * The number of message data bytes in the End
> +			 * transaction can range from 1 to 32 bytes.
> +			 * As per IPMI spec 2.0(section 12.15,Table 12-10),
> +			 * the BMC Multi-part Write commands are:
> +			 * Start-first part	- 06h
> +			 * Middle-part(s)	- 07h
> +			 * End-part		- 08h
> +			 * Update command for END part transaction.
>   			 */
>   			ssif_info->multi_data = NULL;
> +			command = SSIF_IPMI_MULTI_PART_REQUEST_END;
> +		}
>   
>   		rv = ssif_i2c_send(ssif_info, msg_written_handler,
>   				  I2C_SMBUS_WRITE,
> -				  SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE,
> +				  command,
>   				  data_to_send,
>   				  I2C_SMBUS_BLOCK_DATA);
>   		if (rv < 0) {
> @@ -1499,9 +1513,11 @@ static int ssif_probe(struct i2c_client *client, const struct i2c_device_id *id)
>   			 * start and the next message is always going
>   			 * to be 1-31 bytes in length.  Not ideal, but
>   			 * it should work.
> +			 * As per IPMI spec 2.0, SSIF interface supports
> +			 * message size up to 255 bytes.
>   			 */
> -			if (ssif_info->max_xmit_msg_size > 63)
> -				ssif_info->max_xmit_msg_size = 63;
> +			if (ssif_info->max_xmit_msg_size > SSIF_MAX_MSG_LENGTH)
> +				ssif_info->max_xmit_msg_size = SSIF_MAX_MSG_LENGTH;
>   			break;
>   
>   		default: