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

[Yanling Song <songyl@ramaxel.com>]

On Wed, 13 Oct 2021 15:00:07 -0700
Bart Van Assche <bvanassche@acm.org> wrote:

> On 10/12/21 11:50 PM, Yanling Song wrote:
> > On Tue, 12 Oct 2021 09:59:30 -0700
> > Bart Van Assche <bvanassche@acm.org> wrote:  
> >> Why is it that SG_IO is not sufficient? This is something that
> >> should have been explained in the patch description.  
> > 
> > There are two cases that there are no SG devices and SG_IO cannot
> > work. 1. To access raid controller:
> > a. Raid controller is a scsi host, not a scsi device, so there
> > is no SG device associated with it.
> > b. Even there is a scsi device for raid controller, SG_IO
> > cannot work when something wrong with IO queue and only admin queue
> > can work;
> > 2. To access the physical disks behinds raid controller:
> > raid controller only reports VDs to OS and only VDs have SG
> > devices. OS has no idea about physical disks behinds raid
> > controller and there is no SG devices associated with physical
> > disks.  
> 
> Please take a look at the bsg_setup_queue() call in ufs_bsg_probe(). 
> That call associates a BSG queue with the UFS host. That queue
> supports requests of type struct ufs_bsg_request. The Fibre Channel
> transport driver does something similar. I believe that this is a
> better solution than introducing entirely new ioctls.

I need some time to investigate it. will response later.

> 
> >>>> Additionally, mixing driver-internal and user space definitions
> >>>> in a single header file is not OK. Definitions of data
> >>>> structures and ioctls that are needed by user space software
> >>>> should occur in a header file in the directory
> >>>> include/uapi/scsi/.  
> >>>
> >>> Sounds reasonable. But after checking the directory
> >>> include/uapi/scsi/, there are only several files in it. It is
> >>> expected that there should be many files if developers follow the
> >>> rule. Do you know why?  
> >>
> >> If this rule is not followed, that will be a red flag for the SCSI
> >> maintainer and something that will probably delay upstream
> >> acceptance of this patch.  
> > 
> > Since there are not much examples in include/uapi/scsi/, what' your
> > suggestion on how to put the definitions into the folder? for
> > example, what's the file name? spraid_ioctrl.h?  
> 
> How about include/uapi/scsi/spraid.h, since I assume that that header 
> file will cover all user space interfaces for interaction with the 
> spraid driver?
> 
> Thanks,
> 
> Bart.
>