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X-CSE-ConnectionGUID: Xpb/j8IjSauYsbpQPUx0lw== X-CSE-MsgGUID: Pm+vsTdVQpO5h6ykHLqdcQ== X-IronPort-AV: E=McAfee;i="6800,10657,11563"; a="61096420" X-IronPort-AV: E=Sophos;i="6.18,291,1751266800"; d="scan'208";a="61096420" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2025 11:11:14 -0700 X-CSE-ConnectionGUID: jvUa3VO0THexc3SFXzDxJA== X-CSE-MsgGUID: 2hkBBAw1QOm3+rhPbA3ZuA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,291,1751266800"; d="scan'208";a="177531914" Received: from gabaabhi-mobl2.amr.corp.intel.com (HELO [10.125.108.218]) ([10.125.108.218]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2025 11:11:13 -0700 Message-ID: <43772918-1911-46a5-8165-bf612056a8e6@intel.com> Date: Wed, 24 Sep 2025 11:11:12 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V3 15/20] cxl: Add a routine to find cxl root decoder on cxl bus using cxl port To: Neeraj Kumar , linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, gost.dev@samsung.com Cc: a.manzanares@samsung.com, vishak.g@samsung.com, neeraj.kernel@gmail.com, cpgs@samsung.com References: <20250917134116.1623730-1-s.neeraj@samsung.com> <20250917134116.1623730-16-s.neeraj@samsung.com> Content-Language: en-US From: Dave Jiang In-Reply-To: <20250917134116.1623730-16-s.neeraj@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/17/25 6:41 AM, Neeraj Kumar wrote: > Add cxl_find_root_decoder_by_port() to find root decoder on cxl bus. > It is used to find root decoder using cxl port. > > Signed-off-by: Neeraj Kumar > --- > drivers/cxl/core/port.c | 27 +++++++++++++++++++++++++++ > drivers/cxl/cxl.h | 1 + > 2 files changed, 28 insertions(+) > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index 8f36ff413f5d..647d9ce32b64 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -518,6 +518,33 @@ struct cxl_switch_decoder *to_cxl_switch_decoder(struct device *dev) > } > EXPORT_SYMBOL_NS_GPL(to_cxl_switch_decoder, "CXL"); > > +static int match_root_decoder(struct device *dev, const void *data) > +{ > + return is_root_decoder(dev); > +} > + > +/** > + * cxl_find_root_decoder_by_port() - find a cxl root decoder on cxl bus > + * @port: any descendant port in CXL port topology > + */ > +struct cxl_root_decoder *cxl_find_root_decoder_by_port(struct cxl_port *port) > +{ > + struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port); > + struct device *dev; > + > + if (!cxl_root) > + return NULL; > + > + dev = device_find_child(&cxl_root->port.dev, NULL, match_root_decoder); > + if (!dev) > + return NULL; > + > + /* Release device ref taken via device_find_child() */ > + put_device(dev); Should the caller release the device reference instead? DJ > + return to_cxl_root_decoder(dev); > +} > +EXPORT_SYMBOL_NS_GPL(cxl_find_root_decoder_by_port, "CXL"); > + > static void cxl_ep_release(struct cxl_ep *ep) > { > put_device(ep->ep); > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 3abadc3dc82e..1eb1aca7c69f 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -866,6 +866,7 @@ struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev); > bool is_cxl_nvdimm(struct device *dev); > int devm_cxl_add_nvdimm(struct cxl_port *parent_port, struct cxl_memdev *cxlmd); > struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port); > +struct cxl_root_decoder *cxl_find_root_decoder_by_port(struct cxl_port *port); > > #ifdef CONFIG_CXL_REGION > bool is_cxl_pmem_region(struct device *dev);