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Subject: Re: [PATCH 10/10] ocxl: Conditionally bind SCM devices to the
 generic OCXL driver
From:   "Alastair D'Silva" <alastair@au1.ibm.com>
To:     Frederic Barrat <fbarrat@linux.ibm.com>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Andrew Donnellan <ajd@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Keith Busch <keith.busch@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Anton Blanchard <anton@ozlabs.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Vasant Hegde <hegdevasant@linux.vnet.ibm.com>,
        David Gibson <david@gibson.dropbear.id.au>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Allison Randal <allison@lohutok.net>,
        Anju T Sudhakar <anju@linux.vnet.ibm.com>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        =?ISO-8859-1?Q?C=E9dric?= Le Goater <clg@kaod.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kurz <groug@kaod.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        Oscar Salvador <osalvador@suse.com>,
        Michal Hocko <mhocko@suse.com>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Wei Yang <richard.weiyang@gmail.com>, Qian Cai <cai@lca.pw>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, linux-mm@kvack.org
Date:   Fri, 08 Nov 2019 11:37:14 +1100
In-Reply-To: <b70644d6-2c71-cd71-5d00-e25d99beea91@linux.ibm.com>
References: <20191025044721.16617-1-alastair@au1.ibm.com>
         <20191025044721.16617-11-alastair@au1.ibm.com>
         <b70644d6-2c71-cd71-5d00-e25d99beea91@linux.ibm.com>
Organization: IBM Australia
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On Thu, 2019-11-07 at 19:08 +0100, Frederic Barrat wrote:
> 
> Le 25/10/2019 à 06:47, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > This patch allows the user to bind OpenCAPI SCM devices to the
> > generic OCXL
> > driver.
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> 
> I'm wondering if we should upstream this. Is it of any use outside
> of 
> some serious debug session for a developer?
> Also we would now have 2 drivers picking up the same device ID,
> since 
> the SCM driver is always registering for that ID, irrespective of 
> CONFIG_OCXL_SCM_GENERIC
> 
>    Fred
> 

I think I'll drop this patch. It's easy enough to maintain out-of-tree
for our in-house SCM hardware engineers.

> 
> >   drivers/misc/ocxl/Kconfig | 7 +++++++
> >   drivers/misc/ocxl/pci.c   | 3 +++
> >   2 files changed, 10 insertions(+)
> > 
> > diff --git a/drivers/misc/ocxl/Kconfig b/drivers/misc/ocxl/Kconfig
> > index 1916fa65f2f2..8a683715c97c 100644
> > --- a/drivers/misc/ocxl/Kconfig
> > +++ b/drivers/misc/ocxl/Kconfig
> > @@ -29,3 +29,10 @@ config OCXL
> >   	  dedicated OpenCAPI link, and don't follow the same protocol.
> >   
> >   	  If unsure, say N.
> > +
> > +config OCXL_SCM_GENERIC
> > +	bool "Treat OpenCAPI Storage Class Memory as a generic OpenCAPI
> > device"
> > +	default n
> > +	help
> > +	  Select this option to treat OpenCAPI Storage Class Memory
> > +	  devices an generic OpenCAPI devices.
> > diff --git a/drivers/misc/ocxl/pci.c b/drivers/misc/ocxl/pci.c
> > index cb920aa88d3a..7137055c1883 100644
> > --- a/drivers/misc/ocxl/pci.c
> > +++ b/drivers/misc/ocxl/pci.c
> > @@ -10,6 +10,9 @@
> >    */
> >   static const struct pci_device_id ocxl_pci_tbl[] = {
> >   	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x062B), },
> > +#ifdef CONFIG_OCXL_SCM_GENERIC
> > +	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0625), },
> > +#endif
> >   	{ }
> >   };
> >   MODULE_DEVICE_TABLE(pci, ocxl_pci_tbl);
> > 
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819