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Date:   Tue, 18 Jun 2019 11:49:36 -0700
From:   Haren Myneni <haren@linux.vnet.ibm.com>
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To:     Michael Ellerman <mpe@ellerman.id.au>
CC:     Herbert Xu <herbert@gondor.apana.org.au>,
        linuxppc-dev@lists.ozlabs.org, linux-crypto@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [EXTERNAL] Re: crypto/NX: Set receive window credits to max number
 of CRBs in RxFIFO
References: <1560587942.17547.18.camel@hbabu-laptop> <87ef3royva.fsf@concordia.ellerman.id.au>
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On 06/18/2019 05:35 AM, Michael Ellerman wrote:
> Haren Myneni <haren@linux.vnet.ibm.com> writes:
>>     
>> System gets checkstop if RxFIFO overruns with more requests than the
>> maximum possible number of CRBs in FIFO at the same time. So find max
>> CRBs from FIFO size and set it to receive window credits.
>>    
>> CC: stable@vger.kernel.org # v4.14+
>> Signed-off-by:Haren Myneni <haren@us.ibm.com>
> 
> It's helpful to mention the actual commit that's fixed, so that people
> with backports can join things up, so should that be:
> 
>   Fixes: b0d6c9bab5e4 ("crypto/nx: Add P9 NX support for 842 compression engine")
> 
> ???

Sorry, Yes, We use 1K for Rx window credits in b0d6c9bab5e41d07f (crypto/nx: Add P9 NX support for 842 compression engine). But credits should be based on FIFO size. 

I will repost the patch.  

> 
> cheers
> 
>> diff --git a/drivers/crypto/nx/nx-842-powernv.c b/drivers/crypto/nx/nx-842-powernv.c
>> index 4acbc47..e78ff5c 100644
>> --- a/drivers/crypto/nx/nx-842-powernv.c
>> +++ b/drivers/crypto/nx/nx-842-powernv.c
>> @@ -27,8 +27,6 @@
>>  #define WORKMEM_ALIGN	(CRB_ALIGN)
>>  #define CSB_WAIT_MAX	(5000) /* ms */
>>  #define VAS_RETRIES	(10)
>> -/* # of requests allowed per RxFIFO at a time. 0 for unlimited */
>> -#define MAX_CREDITS_PER_RXFIFO	(1024)
>>  
>>  struct nx842_workmem {
>>  	/* Below fields must be properly aligned */
>> @@ -812,7 +810,11 @@ static int __init vas_cfg_coproc_info(struct device_node *dn, int chip_id,
>>  	rxattr.lnotify_lpid = lpid;
>>  	rxattr.lnotify_pid = pid;
>>  	rxattr.lnotify_tid = tid;
>> -	rxattr.wcreds_max = MAX_CREDITS_PER_RXFIFO;
>> +	/*
>> +	 * Maximum RX window credits can not be more than #CRBs in
>> +	 * RxFIFO. Otherwise, can get checkstop if RxFIFO overruns.
>> +	 */
>> +	rxattr.wcreds_max = fifo_size / CRB_SIZE;
>>  
>>  	/*
>>  	 * Open a VAS receice window which is used to configure RxFIFO
>