linux-kernel - Re: crypto/nx842: Ignore queue overflow informative error

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Message-ID: <87bna36v91.fsf@gamma.ozlabs.ibm.com>
Date:	Mon, 07 Dec 2015 09:57:14 +1100
From:	Daniel Axtens <dja@...ens.net>
To:	Haren Myneni <haren@...ux.vnet.ibm.com>,
	herbert@...dor.apana.org.au, davem@...emloft.net,
	ddstreet@...e.org, mpe@...erman.id.au, pair@...ibm.com,
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: crypto/nx842: Ignore queue overflow informative error

Haren Myneni <haren@...ux.vnet.ibm.com> writes:

> NX842 coprocessor sets bit 3 if queue is overflow. It is just for
> information to the user. So the driver prints this informative message
> and ignores it.

What queue, and what happens when the queue overflows? It seems like
*something* would need to be done, somewhere, by someone?

I realise that as a piece of IBM hardware this is probably an incredibly
optimistic question, but is this behaviour documented publically anywhere?
(As a distant second best, is it documented internally anywhere that I
can read?)

> --- a/drivers/crypto/nx/nx-842-powernv.c
> +++ b/drivers/crypto/nx/nx-842-powernv.c
> @@ -442,6 +442,15 @@ static int nx842_powernv_function(const unsigned char *in, unsigned int inlen,
>  			     (unsigned int)ccw,
>  			     (unsigned int)be32_to_cpu(crb->ccw));
>  
> +	/*
> +	 * NX842 coprocessor uses 3rd bit to report queue overflow which is
> +	 * not an error, just for information to user. So, ignore this bit.
> +	 */
> +	if (ret & ICSWX_BIT3) {
> +		pr_info_ratelimited("842 coprocessor queue overflow\n");
It doesn't look like this is done anywhere else in the file, but should
this be prefixed with something? Something like "nx-842: Coprocessor
queue overflow"?

Regards,
Daniel

> +		ret &= ~ICSWX_BIT3;
> +	}
> +
>  	switch (ret) {
>  	case ICSWX_INITIATED:
>  		ret = wait_for_csb(wmem, csb);
>
>
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