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Subject: Re: [PATCH v2 04/17] ibmvfc: add alloc/dealloc routines for SCSI
 Sub-CRQ Channels
To:     Brian King <brking@linux.vnet.ibm.com>,
        james.bottomley@hansenpartnership.com
Cc:     martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        brking@linux.ibm.com
References: <20201202005329.4538-1-tyreld@linux.ibm.com>
 <20201202005329.4538-5-tyreld@linux.ibm.com>
 <f0b848d3-0a39-dd95-e4a2-b303c12ed0dd@linux.vnet.ibm.com>
From:   Tyrel Datwyler <tyreld@linux.ibm.com>
Message-ID: <6f9dc1e8-76fe-0251-3e43-edf7da93eb82@linux.ibm.com>
Date:   Wed, 2 Dec 2020 14:23:49 -0800
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On 12/2/20 7:25 AM, Brian King wrote:
> On 12/1/20 6:53 PM, Tyrel Datwyler wrote:
>> +static int ibmvfc_register_scsi_channel(struct ibmvfc_host *vhost,
>> +				  int index)
>> +{
>> +	struct device *dev = vhost->dev;
>> +	struct vio_dev *vdev = to_vio_dev(dev);
>> +	struct ibmvfc_sub_queue *scrq = &vhost->scsi_scrqs.scrqs[index];
>> +	int rc = -ENOMEM;
>> +
>> +	ENTER;
>> +
>> +	scrq->msgs = (struct ibmvfc_sub_crq *)get_zeroed_page(GFP_KERNEL);
>> +	if (!scrq->msgs)
>> +		return rc;
>> +
>> +	scrq->size = PAGE_SIZE / sizeof(*scrq->msgs);
>> +	scrq->msg_token = dma_map_single(dev, scrq->msgs, PAGE_SIZE,
>> +					 DMA_BIDIRECTIONAL);
>> +
>> +	if (dma_mapping_error(dev, scrq->msg_token))
>> +		goto dma_map_failed;
>> +
>> +	rc = h_reg_sub_crq(vdev->unit_address, scrq->msg_token, PAGE_SIZE,
>> +			   &scrq->cookie, &scrq->hw_irq);
>> +
>> +	if (rc) {
>> +		dev_warn(dev, "Error registering sub-crq: %d\n", rc);
>> +		dev_warn(dev, "Firmware may not support MQ\n");
> 
> Will this now get logged everywhere this new driver runs if the firmware
> does not support sub CRQs? Is there something better that could be done
> here to only log this for a true error and not just because a new driver
> is running with an older firmware release?

I suppose we can guess if the rc is H_PARAMETER that sub-crqs are probably not
supported and do a dev_warn_once() for the no MQ support message. H_PARAMETER
could mean other things though so we still need to log the failure in my opinion.

-Tyrel

> 
>> +		goto reg_failed;
>> +	}
>> +
>> +	scrq->hwq_id = index;
>> +	scrq->vhost = vhost;
>> +
>> +	LEAVE;
>> +	return 0;
>> +
>> +reg_failed:
>> +	dma_unmap_single(dev, scrq->msg_token, PAGE_SIZE, DMA_BIDIRECTIONAL);
>> +dma_map_failed:
>> +	free_page((unsigned long)scrq->msgs);
>> +	LEAVE;
>> +	return rc;
>> +}
>> +
> 
> 
>