Re: [PATCH] megaraid_sas: Do not use 32-bit atomic request descriptor for Ventura controllers

[Tomas Henzl <thenzl@redhat.com>]

On 02/12/2018 06:39 AM, Shivasharan S wrote:
> Problem Statement:
> Sending I/O through 32 bit descriptors to Ventura series of controller
> results in IO timeout on certain conditions.
>  
> This error only occurs on systems with high I/O activity on
> Ventura series controllers.
>   
> Changes in this patch will prevent driver from using 32 bit descriptor
> and use 64 bit Descriptors.
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
> Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
> ---
>  drivers/scsi/megaraid/megaraid_sas_fusion.c | 37 ++++++++++-------------------
>  1 file changed, 12 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> index 073ced07e662..09f2bdb14b0a 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> @@ -226,26 +226,21 @@ static void
>  megasas_fire_cmd_fusion(struct megasas_instance *instance,
>  		union MEGASAS_REQUEST_DESCRIPTOR_UNION *req_desc)
>  {
> -	if (instance->adapter_type == VENTURA_SERIES)
> -		writel(le32_to_cpu(req_desc->u.low),
> -			&instance->reg_set->inbound_single_queue_port);
> -	else {
>  #if defined(writeq) && defined(CONFIG_64BIT)
> -		u64 req_data = (((u64)le32_to_cpu(req_desc->u.high) << 32) |
> -				le32_to_cpu(req_desc->u.low));
> +	u64 req_data = (((u64)le32_to_cpu(req_desc->u.high) << 32) |
> +		le32_to_cpu(req_desc->u.low));
>  
> -		writeq(req_data, &instance->reg_set->inbound_low_queue_port);
> +	writeq(req_data, &instance->reg_set->inbound_low_queue_port);
>  #else
> -		unsigned long flags;
> -		spin_lock_irqsave(&instance->hba_lock, flags);
> -		writel(le32_to_cpu(req_desc->u.low),
> -			&instance->reg_set->inbound_low_queue_port);
> -		writel(le32_to_cpu(req_desc->u.high),
> -			&instance->reg_set->inbound_high_queue_port);
> -		mmiowb();
> -		spin_unlock_irqrestore(&instance->hba_lock, flags);
> +	unsigned long flags;
> +	spin_lock_irqsave(&instance->hba_lock, flags);
> +	writel(le32_to_cpu(req_desc->u.low),
> +		&instance->reg_set->inbound_low_queue_port);
> +	writel(le32_to_cpu(req_desc->u.high),
> +		&instance->reg_set->inbound_high_queue_port);
> +	mmiowb();
> +	spin_unlock_irqrestore(&instance->hba_lock, flags);
>  #endif
> -	}
>  }
>  
>  /**
> @@ -982,7 +977,6 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
>  	const char *sys_info;
>  	MFI_CAPABILITIES *drv_ops;
>  	u32 scratch_pad_2;
> -	unsigned long flags;
>  	ktime_t time;
>  	bool cur_fw_64bit_dma_capable;
>  
> @@ -1121,14 +1115,7 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
>  			break;
>  	}
>  
> -	/* For Ventura also IOC INIT required 64 bit Descriptor write. */
> -	spin_lock_irqsave(&instance->hba_lock, flags);
> -	writel(le32_to_cpu(req_desc.u.low),
> -	       &instance->reg_set->inbound_low_queue_port);
> -	writel(le32_to_cpu(req_desc.u.high),
> -	       &instance->reg_set->inbound_high_queue_port);
> -	mmiowb();
> -	spin_unlock_irqrestore(&instance->hba_lock, flags);
> +	megasas_fire_cmd_fusion(instance, &req_desc);
>  
>  	wait_and_poll(instance, cmd, MFI_POLL_TIMEOUT_SECS);
>  

Reviewed-by: Tomas Henzl <thenzl@redhat.com>

Please also remove the text
 * Ventura supports 32 bit Descriptor.
 * Prior to Ventura (12G) MR controller supports 64 bit Descriptor.
from the function description (not urgent may happen later)

Thanks,
Tomas