Re: [PATCH V2] scsi:spraid: initial commit of Ramaxel spraid driver

From: Hannes Reinecke <hare@suse.de>
To: Yanling Song <songyl@ramaxel.com>,
	martin.petersen@oracle.com, bvanassche@acm.org
Cc: linux-scsi@vger.kernel.org, yujiang@ramaxel.com
Subject: Re: [PATCH V2] scsi:spraid: initial commit of Ramaxel spraid driver
Date: Mon, 29 Nov 2021 14:04:12 +0100	[thread overview]
Message-ID: <99fb2d55-88c0-2911-3b71-7670d386ab1c@suse.de> (raw)
In-Reply-To: <20211126073310.87683-1-songyl@ramaxel.com>

On 11/26/21 8:33 AM, Yanling Song wrote:
> This initial commit contains Ramaxel's spraid module.
> 
> Signed-off-by: Yanling Song <songyl@ramaxel.com>
> 
> Changes from V1:
> 1. Use BSG module to replace with ioctrl
> 2. Use author's email as MODULE_AUTHOR
> 3. Remove "default=m" in drivers/scsi/spraid/Kconfig
> 4. To be changed in the next version:
>     a. Use get_unaligned_be*() in spraid_setup_rw_cmd();
>     b. Use pr_debug() instead of introducing dev_log_dbg().
> 
> ---
>   Documentation/scsi/spraid.rst     |   16 +
>   MAINTAINERS                       |    7 +
>   drivers/scsi/Kconfig              |    1 +
>   drivers/scsi/Makefile             |    1 +
>   drivers/scsi/spraid/Kconfig       |   10 +
>   drivers/scsi/spraid/Makefile      |    7 +
>   drivers/scsi/spraid/spraid.h      |  693 ++++++
>   drivers/scsi/spraid/spraid_main.c | 3328 +++++++++++++++++++++++++++++
>   8 files changed, 4063 insertions(+)
>   create mode 100644 Documentation/scsi/spraid.rst
>   create mode 100644 drivers/scsi/spraid/Kconfig
>   create mode 100644 drivers/scsi/spraid/Makefile
>   create mode 100644 drivers/scsi/spraid/spraid.h
>   create mode 100644 drivers/scsi/spraid/spraid_main.c
> 
Hmm.
This entire thing looks like an NVMe controller which is made to look 
like a SCSI controller.
It even uses most of the NVMe structures.
And from what I've seen there is not much SCSI specific in here; I/O and 
queue setup is pretty much what every NVMe controller does.
So why not make it a true NVMe controller?
Yes, you would need to discuss with the NVMe folks on how a RAID 
controller should look like in NVMe terms.
But overall I guess the driver would be far smaller and possibly easier 
to maintain.

So where's the benefit having it as a SCSI driver (apart from the fact 
that is allows you to side-step having to discuss the interface with 
NVMexpress.org ...)?
Or, to put it the other way round: Is there anything SCSI specific which 
would prevent such an approach?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke <hare@suse.de>
<insert signature here>