RE: [PATCH v2 4/4] fpga: remove compat_id from fpga_manager and fpga_region

["Wu, Hao" <hao.wu@intel.com>]

> On 7/11/21 6:40 PM, Wu, Hao wrote:
> >> -----Original Message-----
> >> From: trix@redhat.com <trix@redhat.com>
> >> Sent: Friday, July 9, 2021 9:42 PM
> >> To: mdf@kernel.org; corbet@lwn.net; Wu, Hao <hao.wu@intel.com>
> >> Cc: linux-fpga@vger.kernel.org; linux-doc@vger.kernel.org; linux-
> >> kernel@vger.kernel.org; Tom Rix <trix@redhat.com>
> >> Subject: [PATCH v2 4/4] fpga: remove compat_id from fpga_manager and
> >> fpga_region
> >>
> >> From: Tom Rix <trix@redhat.com>
> >>
> >> compat_id is implementation specific.  So the data should be
> >> stored at the implemeation layer, not the infrastructure layer.
> >> Remove the compat_id elements and supporting code.
> > I think current compat_id format can meet the checking requirement.
> > Actually I hope other hardware which needs compatible checking
> > to expose the same format compat_id. Then we can have more
> > unified/common code, e.g. userspace application/lib handling.
> 
> v2 does not change the current ABI. The dfl output is the same as
> before, the other nonusers get -ENOENT.

I think the common ABI is changed somehow, as output format can
be anything with your change, this confuses userspace too.

> 
> For dfl compat_id is 2 64 bit registers.
> 
> For compat_id to be useful to the others, they need the flexibility to
> print to the sysfs in the manner that aligns with whatever their user
> library interface is, 2 64 values isn't going to work for everyone.  ex/
> xrt likely would be a uuid_t printed out a special way. someone else
> maybe just string in the board fw, maybe some has a 8 or 256 bits of
> compat_id  etc.
> 
> as a driver region specific op, others are free to do whatever is required.
> 
> > Currently I didn't see any other usage or requirement on this part
> > now, only DFL uses it.  So should we leave it here at this moment?
> > I feel we don't have to change it for now to move it to a
> > Per-fpga-mgr format. : )
> 
> The motivation for doing this now is the 'use standard class dev release
> .. ' patchset
> 
> I really do not like 2 register functions.
> 
> By moving compat_id, the 2 register functions reduces down to 1.
> 

You don't have to moving compact_id, you can have 1 parameter
with a data structure including everything.

Thanks
Hao

> I did a poc here
> 
> https://lore.kernel.org/linux-fpga/20210709184511.2521508-1-
> trix@redhat.com/
> 
> Tom
> 
> >
> > Thanks
> > Hao
> >
> >> Printing out the compat_id is done with the fpga_region
> >> compat_id_show() op.
> >>
> >> Signed-off-by: Tom Rix <trix@redhat.com>
> >> ---
> >>   drivers/fpga/dfl-fme-mgr.c       |  7 -------
> >>   drivers/fpga/dfl-fme-region.c    |  1 -
> >>   drivers/fpga/fpga-region.c       |  7 +------
> >>   include/linux/fpga/fpga-mgr.h    | 13 -------------
> >>   include/linux/fpga/fpga-region.h |  2 --
> >>   5 files changed, 1 insertion(+), 29 deletions(-)
> >>
> >> diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
> >> index cd0b9157ea6e5..8c5423eeffe75 100644
> >> --- a/drivers/fpga/dfl-fme-mgr.c
> >> +++ b/drivers/fpga/dfl-fme-mgr.c
> >> @@ -292,7 +292,6 @@ EXPORT_SYMBOL_GPL(fme_mgr_get_compat_id);
> >>   static int fme_mgr_probe(struct platform_device *pdev)
> >>   {
> >>   	struct dfl_fme_mgr_pdata *pdata = dev_get_platdata(&pdev->dev);
> >> -	struct fpga_compat_id *compat_id;
> >>   	struct device *dev = &pdev->dev;
> >>   	struct fme_mgr_priv *priv;
> >>   	struct fpga_manager *mgr;
> >> @@ -312,10 +311,6 @@ static int fme_mgr_probe(struct platform_device
> >> *pdev)
> >>   			return PTR_ERR(priv->ioaddr);
> >>   	}
> >>
> >> -	compat_id = devm_kzalloc(dev, sizeof(*compat_id), GFP_KERNEL);
> >> -	if (!compat_id)
> >> -		return -ENOMEM;
> >> -
> >>   	_fme_mgr_get_compat_id(priv->ioaddr, &priv->compat_id);
> >>
> >>   	mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
> >> @@ -323,8 +318,6 @@ static int fme_mgr_probe(struct platform_device
> *pdev)
> >>   	if (!mgr)
> >>   		return -ENOMEM;
> >>
> >> -	mgr->compat_id = compat_id;
> >> -
> >>   	return devm_fpga_mgr_register(dev, mgr);
> >>   }
> >>
> >> diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
> >> index d21eacbf2469f..be1d57ee37666 100644
> >> --- a/drivers/fpga/dfl-fme-region.c
> >> +++ b/drivers/fpga/dfl-fme-region.c
> >> @@ -64,7 +64,6 @@ static int fme_region_probe(struct platform_device
> *pdev)
> >>   	}
> >>
> >>   	region->priv = pdata;
> >> -	region->compat_id = mgr->compat_id;
> >>   	platform_set_drvdata(pdev, region);
> >>
> >>   	ret = fpga_region_register(region);
> >> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> >> index 864dd4f290e3b..b08d3914716f0 100644
> >> --- a/drivers/fpga/fpga-region.c
> >> +++ b/drivers/fpga/fpga-region.c
> >> @@ -172,12 +172,7 @@ static ssize_t compat_id_show(struct device *dev,
> >>   	if (region->rops && region->rops->compat_id_show)
> >>   		return region->rops->compat_id_show(region, buf);
> >>
> >> -	if (!region->compat_id)
> >> -		return -ENOENT;
> >> -
> >> -	return sprintf(buf, "%016llx%016llx\n",
> >> -		       (unsigned long long)region->compat_id->id_h,
> >> -		       (unsigned long long)region->compat_id->id_l);
> >> +	return -ENOENT;
> >>   }
> >>
> >>   static DEVICE_ATTR_RO(compat_id);
> >> diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
> >> index ec2cd8bfceb00..ebdea215a8643 100644
> >> --- a/include/linux/fpga/fpga-mgr.h
> >> +++ b/include/linux/fpga/fpga-mgr.h
> >> @@ -143,24 +143,12 @@ struct fpga_manager_ops {
> >>   #define FPGA_MGR_STATUS_IP_PROTOCOL_ERR		BIT(3)
> >>   #define FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR	BIT(4)
> >>
> >> -/**
> >> - * struct fpga_compat_id - id for compatibility check
> >> - *
> >> - * @id_h: high 64bit of the compat_id
> >> - * @id_l: low 64bit of the compat_id
> >> - */
> >> -struct fpga_compat_id {
> >> -	u64 id_h;
> >> -	u64 id_l;
> >> -};
> >> -
> >>   /**
> >>    * struct fpga_manager - fpga manager structure
> >>    * @name: name of low level fpga manager
> >>    * @dev: fpga manager device
> >>    * @ref_mutex: only allows one reference to fpga manager
> >>    * @state: state of fpga manager
> >> - * @compat_id: FPGA manager id for compatibility check.
> >>    * @mops: pointer to struct of fpga manager ops
> >>    * @priv: low level driver private date
> >>    */
> >> @@ -169,7 +157,6 @@ struct fpga_manager {
> >>   	struct device dev;
> >>   	struct mutex ref_mutex;
> >>   	enum fpga_mgr_states state;
> >> -	struct fpga_compat_id *compat_id;
> >>   	const struct fpga_manager_ops *mops;
> >>   	void *priv;
> >>   };
> >> diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-
> region.h
> >> index 236d3819f1c13..afc79784b2823 100644
> >> --- a/include/linux/fpga/fpga-region.h
> >> +++ b/include/linux/fpga/fpga-region.h
> >> @@ -30,7 +30,6 @@ struct fpga_region_ops {
> >>    * @bridge_list: list of FPGA bridges specified in region
> >>    * @mgr: FPGA manager
> >>    * @info: FPGA image info
> >> - * @compat_id: FPGA region id for compatibility check.
> >>    * @priv: private data
> >>    * @rops: optional pointer to struct for fpga region ops
> >>    */
> >> @@ -40,7 +39,6 @@ struct fpga_region {
> >>   	struct list_head bridge_list;
> >>   	struct fpga_manager *mgr;
> >>   	struct fpga_image_info *info;
> >> -	struct fpga_compat_id *compat_id;
> >>   	void *priv;
> >>   	const struct fpga_region_ops *rops;
> >>   };
> >> --
> >> 2.26.3