linux-kernel - Re: [PATCH v4 15/19] fpga: dfl: convert is_feature_dev

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Message-ID: <bad311610de9738e88982fabc46c04b15cdc3650.camel@intel.com>
Date: Mon, 18 Nov 2024 23:00:28 +0000
From: "Colberg, Peter" <peter.colberg@...el.com>
To: "yilun.xu@...ux.intel.com" <yilun.xu@...ux.intel.com>
CC: "Xu, Yilun" <yilun.xu@...el.com>, "linux-fpga@...r.kernel.org"
	<linux-fpga@...r.kernel.org>, "mdf@...nel.org" <mdf@...nel.org>, "Wu, Hao"
	<hao.wu@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "russ.weight@...ux.dev"
	<russ.weight@...ux.dev>, "Pagani, Marco" <marpagan@...hat.com>,
	"trix@...hat.com" <trix@...hat.com>,
	"basheer.ahmed.muddebihal@...ux.intel.com"
	<basheer.ahmed.muddebihal@...ux.intel.com>, "matthew.gerlach@...ux.intel.com"
	<matthew.gerlach@...ux.intel.com>
Subject: Re: [PATCH v4 15/19] fpga: dfl: convert is_feature_dev_detected() to
 use FIU type

On Mon, 2024-11-18 at 22:32 +0800, Xu Yilun wrote:
> On Fri, Oct 25, 2024 at 06:37:10PM -0400, Peter Colberg wrote:
> > Use binfo->type instead of binfo->feature_dev to decide whether a
> > feature device was detected during feature parsing. A subsequent
> > commit will delay the allocation of the feature platform device
> > to feature_dev_register() and remove binfo->feature_dev.
> > 
> > This commit does not introduce any functional changes.
> > 
> > Signed-off-by: Peter Colberg <peter.colberg@...el.com>
> > Reviewed-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> > Reviewed-by: Basheer Ahmed Muddebihal <basheer.ahmed.muddebihal@...ux.intel.com>
> > ---
> > Changes since v3:
> > - New patch extracted from last patch of v3 series.
> > ---
> >  drivers/fpga/dfl.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> > index 758673b0290a..a9ec37278b2d 100644
> > --- a/drivers/fpga/dfl.c
> > +++ b/drivers/fpga/dfl.c
> > @@ -1248,7 +1248,7 @@ static int parse_feature_port_afu(struct build_feature_devs_info *binfo,
> >  return create_feature_instance(binfo, ofst, size, FEATURE_ID_AFU);
> >  }
> >  
> > -#define is_feature_dev_detected(binfo) (!!(binfo)->feature_dev)
> > +#define is_feature_dev_detected(binfo) ((binfo)->type != DFL_ID_MAX)
> 
> I still doesn't get why put the change here. How it resolves my concern
> compared to v3?

Could you elaborate on your concern? I moved this change into a
separate commit so that it is not lost in other changes, but I don't
see how the two definitions would not be functionally equivalent. Would
it help to extend the commit description along the following lines?

   1. Before this series, binfo->feature_dev was initialized to NULL by
      devm_kzalloc() in dfl_fpga_feature_devs_enumerate(). After this
      series, binfo->type is initialized to DFL_ID_MAX in
      dfl_fpga_feature_devs_enumerate().
   2. Before this series, binfo->feature_dev was set to a non-NULL
      pointer in build_info_create_dev(), which in turn was called from
      parse_feature_fiu(). After this series, binfo->type is set to a
      non-DFL_ID_MAX value, as returned by dfh_id_to_type(), in
      parse_feature_fiu().
   3. Before this series, binfo->feature_dev was reset to NULL at the
      end of build_info_commit_dev(). After this series, binfo->type is
      reset to DFL_ID_MAX at the end of build_info_commit_dev().

Thanks,
Peter

> 
> Thanks,
> Yilun
> 
> >  
> >  static int parse_feature_afu(struct build_feature_devs_info *binfo,
> >  resource_size_t ofst)
> > -- 
> > 2.47.0
> > 
> >