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From:   "Banman, Andrew" <abanman@hpe.com>
To:     "minyard@acm.org" <minyard@acm.org>
CC:     "openipmi-developer@lists.sourceforge.net" 
        <openipmi-developer@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Anderson, Russ" <russ.anderson@hpe.com>,
        "Ramsay, Frank" <frank.ramsay@hpe.com>,
        "Ernst, Justin" <justin.ernst@hpe.com>,
        Corey Minyard <cminyard@mvista.com>
Subject: RE: [PATCH 1/2] ipmi: Move BT capabilities detection to the detect
 call
Thread-Topic: [PATCH 1/2] ipmi: Move BT capabilities detection to the detect
 call
Thread-Index: AQHUOyEfRq+wlD+DEU2qdfapZpi27qTUD2Hw
Date:   Mon, 27 Aug 2018 20:16:43 +0000
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 <1535056623-26634-2-git-send-email-minyard@acm.org>
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Tested-by: Andrew Banman

Ran through 100+ boots with no error with your 1st patch applied. I don't see any endcases to worry about.

Thanks Corey!

Andrew

> -----Original Message-----
> From: Corey Minyard [mailto:tcminyard@gmail.com] On Behalf Of
> minyard@acm.org
> Sent: Thursday, August 23, 2018 3:37 PM
> To: Banman, Andrew <abanman@hpe.com>
> Cc: openipmi-developer@lists.sourceforge.net; linux-
> kernel@vger.kernel.org; Anderson, Russ <russ.anderson@hpe.com>; Ramsay,
> Frank <frank.ramsay@hpe.com>; Ernst, Justin <justin.ernst@hpe.com>;
> Corey Minyard <cminyard@mvista.com>
> Subject: [PATCH 1/2] ipmi: Move BT capabilities detection to the detect
> call
> 
> From: Corey Minyard <cminyard@mvista.com>
> 
> The capabilities detection was being done as part of the normal
> state machine, but it was possible for it to be running while
> the upper layers of the IPMI driver were initializing the
> device, resulting in error and failure to initialize.
> 
> Move the capabilities detection to the the detect function,
> so it's done before anything else runs on the device.  This also
> simplifies the state machine and removes some code, as a bonus.
> 
> Signed-off-by: Corey Minyard <cminyard@mvista.com>
> Reported-by: Andrew Banman <abanman@hpe.com>
> ---
>  drivers/char/ipmi/ipmi_bt_sm.c | 92 ++++++++++++++++++++++-------------
> -------
>  1 file changed, 48 insertions(+), 44 deletions(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_bt_sm.c
> b/drivers/char/ipmi/ipmi_bt_sm.c
> index cbc6126..b4133832e 100644
> --- a/drivers/char/ipmi/ipmi_bt_sm.c
> +++ b/drivers/char/ipmi/ipmi_bt_sm.c
> @@ -59,8 +59,6 @@ enum bt_states {
>  	BT_STATE_RESET3,
>  	BT_STATE_RESTART,
>  	BT_STATE_PRINTME,
> -	BT_STATE_CAPABILITIES_BEGIN,
> -	BT_STATE_CAPABILITIES_END,
>  	BT_STATE_LONG_BUSY	/* BT doesn't get hosed :-) */
>  };
> 
> @@ -86,7 +84,6 @@ struct si_sm_data {
>  	int		error_retries;	/* end of "common" fields */
>  	int		nonzero_status;	/* hung BMCs stay all 0 */
>  	enum bt_states	complete;	/* to divert the state machine */
> -	int		BT_CAP_outreqs;
>  	long		BT_CAP_req2rsp;
>  	int		BT_CAP_retries;	/* Recommended retries */
>  };
> @@ -137,8 +134,6 @@ static char *state2txt(unsigned char state)
>  	case BT_STATE_RESET3:		return("RESET3");
>  	case BT_STATE_RESTART:		return("RESTART");
>  	case BT_STATE_LONG_BUSY:	return("LONG_BUSY");
> -	case BT_STATE_CAPABILITIES_BEGIN: return("CAP_BEGIN");
> -	case BT_STATE_CAPABILITIES_END:	return("CAP_END");
>  	}
>  	return("BAD STATE");
>  }
> @@ -185,7 +180,6 @@ static unsigned int bt_init_data(struct si_sm_data
> *bt, struct si_sm_io *io)
>  	bt->complete = BT_STATE_IDLE;	/* end here */
>  	bt->BT_CAP_req2rsp = BT_NORMAL_TIMEOUT * USEC_PER_SEC;
>  	bt->BT_CAP_retries = BT_NORMAL_RETRY_LIMIT;
> -	/* BT_CAP_outreqs == zero is a flag to read BT Capabilities */
>  	return 3; /* We claim 3 bytes of space; ought to check SPMI table
> */
>  }
> 
> @@ -447,7 +441,7 @@ static enum si_sm_result error_recovery(struct
> si_sm_data *bt,
> 
>  static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
>  {
> -	unsigned char status, BT_CAP[8];
> +	unsigned char status;
>  	static enum bt_states last_printed = BT_STATE_PRINTME;
>  	int i;
> 
> @@ -500,12 +494,6 @@ static enum si_sm_result bt_event(struct si_sm_data
> *bt, long time)
>  		if (status & BT_H_BUSY)		/* clear a leftover H_BUSY */
>  			BT_CONTROL(BT_H_BUSY);
> 
> -		bt->timeout = bt->BT_CAP_req2rsp;
> -
> -		/* Read BT capabilities if it hasn't been done yet */
> -		if (!bt->BT_CAP_outreqs)
> -			BT_STATE_CHANGE(BT_STATE_CAPABILITIES_BEGIN,
> -					SI_SM_CALL_WITHOUT_DELAY);
>  		BT_SI_SM_RETURN(SI_SM_IDLE);
> 
>  	case BT_STATE_XACTION_START:
> @@ -610,37 +598,6 @@ static enum si_sm_result bt_event(struct si_sm_data
> *bt, long time)
>  		BT_STATE_CHANGE(BT_STATE_XACTION_START,
>  				SI_SM_CALL_WITH_DELAY);
> 
> -	/*
> -	 * Get BT Capabilities, using timing of upper level state machine.
> -	 * Set outreqs to prevent infinite loop on timeout.
> -	 */
> -	case BT_STATE_CAPABILITIES_BEGIN:
> -		bt->BT_CAP_outreqs = 1;
> -		{
> -			unsigned char GetBT_CAP[] = { 0x18, 0x36 };
> -			bt->state = BT_STATE_IDLE;
> -			bt_start_transaction(bt, GetBT_CAP, sizeof(GetBT_CAP));
> -		}
> -		bt->complete = BT_STATE_CAPABILITIES_END;
> -		BT_STATE_CHANGE(BT_STATE_XACTION_START,
> -				SI_SM_CALL_WITH_DELAY);
> -
> -	case BT_STATE_CAPABILITIES_END:
> -		i = bt_get_result(bt, BT_CAP, sizeof(BT_CAP));
> -		bt_init_data(bt, bt->io);
> -		if ((i == 8) && !BT_CAP[2]) {
> -			bt->BT_CAP_outreqs = BT_CAP[3];
> -			bt->BT_CAP_req2rsp = BT_CAP[6] * USEC_PER_SEC;
> -			bt->BT_CAP_retries = BT_CAP[7];
> -		} else
> -			pr_warn("IPMI BT: using default values\n");
> -		if (!bt->BT_CAP_outreqs)
> -			bt->BT_CAP_outreqs = 1;
> -		pr_warn("IPMI BT: req2rsp=%ld secs retries=%d\n",
> -			bt->BT_CAP_req2rsp / USEC_PER_SEC, bt->BT_CAP_retries);
> -		bt->timeout = bt->BT_CAP_req2rsp;
> -		return SI_SM_CALL_WITHOUT_DELAY;
> -
>  	default:	/* should never occur */
>  		return error_recovery(bt,
>  				      status,
> @@ -651,6 +608,11 @@ static enum si_sm_result bt_event(struct si_sm_data
> *bt, long time)
> 
>  static int bt_detect(struct si_sm_data *bt)
>  {
> +	unsigned char GetBT_CAP[] = { 0x18, 0x36 };
> +	unsigned char BT_CAP[8];
> +	enum si_sm_result smi_result;
> +	int rv;
> +
>  	/*
>  	 * It's impossible for the BT status and interrupt registers to be
>  	 * all 1's, (assuming a properly functioning, self-initialized BMC)
> @@ -661,6 +623,48 @@ static int bt_detect(struct si_sm_data *bt)
>  	if ((BT_STATUS == 0xFF) && (BT_INTMASK_R == 0xFF))
>  		return 1;
>  	reset_flags(bt);
> +
> +	/*
> +	 * Try getting the BT capabilities here.
> +	 */
> +	rv = bt_start_transaction(bt, GetBT_CAP, sizeof(GetBT_CAP));
> +	if (rv) {
> +		dev_warn(bt->io->dev,
> +			 "Can't start capabilities transaction: %d\n", rv);
> +		goto out_no_bt_cap;
> +	}
> +
> +	smi_result = SI_SM_CALL_WITHOUT_DELAY;
> +	for (;;) {
> +		if (smi_result == SI_SM_CALL_WITH_DELAY ||
> +		    smi_result == SI_SM_CALL_WITH_TICK_DELAY) {
> +			schedule_timeout_uninterruptible(1);
> +			smi_result = bt_event(bt, jiffies_to_usecs(1));
> +		} else if (smi_result == SI_SM_CALL_WITHOUT_DELAY) {
> +			smi_result = bt_event(bt, 0);
> +		} else
> +			break;
> +	}
> +
> +	rv = bt_get_result(bt, BT_CAP, sizeof(BT_CAP));
> +	bt_init_data(bt, bt->io);
> +	if (rv < 8) {
> +		dev_warn(bt->io->dev, "bt cap response too short: %d\n", rv);
> +		goto out_no_bt_cap;
> +	}
> +
> +	if (BT_CAP[2]) {
> +		dev_warn(bt->io->dev, "Error fetching bt cap: %x\n",
> BT_CAP[2]);
> +out_no_bt_cap:
> +		dev_warn(bt->io->dev, "using default values\n");
> +	} else {
> +		bt->BT_CAP_req2rsp = BT_CAP[6] * USEC_PER_SEC;
> +		bt->BT_CAP_retries = BT_CAP[7];
> +	}
> +
> +	dev_info(bt->io->dev, "req2rsp=%ld secs retries=%d\n",
> +		 bt->BT_CAP_req2rsp / USEC_PER_SEC, bt->BT_CAP_retries);
> +
>  	return 0;
>  }
> 
> --
> 2.7.4