Re: [PATCH v3] ipmi: update ssif max_xmit_msg_size limit for multi-part messages

[Kamlakant Patel <kpatel@caviumnetworks.com>]

On Mon, Jul 30, 2018 at 07:56:02AM -0500, Corey Minyard wrote:
Hi Corey,
> 
> 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?
I have not received the patch in unicast to me. If you have sent it to
mailing list I will search and test it. If not, could you please resend
it to me, I will test it and let you know.

Thanks,
Kamlakant Patel
> 
> -corey
> 
> >Signed-off-by: Kamlakant Patel <kamlakant.patel@cavium.com>
> >Suggested-by: Robert Richter <robert.richter@cavium.com>
> >Reported-by: Karthikeyan M <karthikeyanm@amiindia.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:
> 
>