RE: [PATCH v2 1/8] cxl: Add helper function to retrieve a feature entry

[Dan Williams <dan.j.williams@intel.com>]

Shiju Jose wrote:
> >-----Original Message-----
> >From: Dan Williams <dan.j.williams@intel.com>
> >Sent: 26 March 2025 21:33
> >To: Shiju Jose <shiju.jose@huawei.com>; linux-cxl@vger.kernel.org;
> >dan.j.williams@intel.com; dave@stgolabs.net; Jonathan Cameron
> ><jonathan.cameron@huawei.com>; dave.jiang@intel.com;
> >alison.schofield@intel.com; vishal.l.verma@intel.com; ira.weiny@intel.com;
> >david@redhat.com; Vilas.Sridharan@amd.com
> >Cc: linux-edac@vger.kernel.org; linux-acpi@vger.kernel.org; linux-
> >mm@kvack.org; linux-kernel@vger.kernel.org; bp@alien8.de;
> >tony.luck@intel.com; rafael@kernel.org; lenb@kernel.org;
> >mchehab@kernel.org; leo.duran@amd.com; Yazen.Ghannam@amd.com;
> >rientjes@google.com; jiaqiyan@google.com; Jon.Grimm@amd.com;
> >dave.hansen@linux.intel.com; naoya.horiguchi@nec.com;
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> >gthelen@google.com; wschwartz@amperecomputing.com;
> >dferguson@amperecomputing.com; wbs@os.amperecomputing.com;
> >nifan.cxl@gmail.com; tanxiaofei <tanxiaofei@huawei.com>; Zengtao (B)
> ><prime.zeng@hisilicon.com>; Roberto Sassu <roberto.sassu@huawei.com>;
> >kangkang.shen@futurewei.com; wanghuiqiang <wanghuiqiang@huawei.com>;
> >Linuxarm <linuxarm@huawei.com>; Shiju Jose <shiju.jose@huawei.com>
> >Subject: Re: [PATCH v2 1/8] cxl: Add helper function to retrieve a feature entry
> >
> >shiju.jose@ wrote:
> >> From: Shiju Jose <shiju.jose@huawei.com>
> >>
> >> Add helper function to retrieve a feature entry from the supported
> >> features list, if supported.
> >>
> >> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> >> Reviewed-by: Fan Ni <fan.ni@samsung.com>
> >> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
> >> ---
> >>  drivers/cxl/core/core.h     |  2 ++
> >>  drivers/cxl/core/features.c | 23 +++++++++++++++++++++++
> >>  2 files changed, 25 insertions(+)
> >>
> >> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index
> >> 1803aedb25ca..16bc717376fc 100644
> >> --- a/drivers/cxl/core/core.h
> >> +++ b/drivers/cxl/core/core.h
> >> @@ -123,6 +123,8 @@ int cxl_ras_init(void);  void cxl_ras_exit(void);
> >>
> >>  #ifdef CONFIG_CXL_FEATURES
> >> +struct cxl_feat_entry *cxl_get_feature_entry(struct cxl_dev_state *cxlds,
> >> +					     const uuid_t *feat_uuid);
> >
> >It is unfortunate that this naming choice is too similar to cxl_get_feature().
> >However, as I go to suggest a new name I find that this is a duplicate of
> >get_support_feature_info() in Dave's fwctl series. Just drop this patch in favor of
> >that.
> 
> Hi Dan,
> 
> I am fine to use get_support_feature_info() for the EDAC features. 
> However this function is defined as static in the fwctl series and 

So, remove static and make it a routine shared between core/features.c
and core/edac.c.

> takes struct fwctl_rpc_cxl * as input for RPC instead of  uuid_t *
> as in cxl_get_feature_entry().
> 
> static struct cxl_feat_entry *
> get_support_feature_info(struct cxl_features_state *cxlfs,
> 			 const struct fwctl_rpc_cxl *rpc_in)
> 
> Can you suggest how to use get_support_feature_info() from within the CXL driver 
> to retrieve a supported feature entry (for e.g an EDAC feature)?

Simply refactor it into something generic that the cxl-edac and
cxl-fwctl path can share:

struct cxl_feat_entry *
cxl_feature_info(struct cxl_features_state *cxlfs, const uuid_t *uuid)

...with the header in drivers/cxl/core/core.h where other cross-core
object helpers are defined.