From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934698AbdBQROG (ORCPT ); Fri, 17 Feb 2017 12:14:06 -0500 Received: from mga02.intel.com ([134.134.136.20]:22458 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934122AbdBQROF (ORCPT ); Fri, 17 Feb 2017 12:14:05 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,172,1484035200"; d="scan'208";a="1098367049" Subject: Re: [RFC 4/8] doc: fpga-mgr: separate getting/locking FPGA manager To: Alan Tull , Moritz Fischer , Jason Gunthorpe References: <1487175261-7051-1-git-send-email-atull@kernel.org> <1487175261-7051-5-git-send-email-atull@kernel.org> Cc: linux-kernel@vger.kernel.org, linux-fpga@vger.kernel.org From: "Li, Yi" Message-ID: <20c28527-8a58-7aa0-489c-5bef7228a159@linux.intel.com> Date: Fri, 17 Feb 2017 11:14:02 -0600 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <1487175261-7051-5-git-send-email-atull@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hi Alan On 2/15/2017 10:14 AM, Alan Tull wrote: > Document that getting a reference to a FPGA Manager has been > separated from locking the FPGA Mangager for use. > > fpga_mgr_lock/unlock functions get/release mutex. > > of_fpga_mgr_get, fpga_mgr_get, and fpga_mgr_put no longer lock > the FPGA manager mutex. > > This makes it more straigtforward to save a reference to > a FPGA manager and only attempting to lock it when programming > the FPGA. New to the FPGA world, but I like the idea of shorter lock. Separating the lock from fpga_mgr_get will give underline FPGA device drivers more flexibility to acquire the mgr pointer. One newbie question, since the underline FPGA device driver does the fpga_mgr_register during probe, each manager instance belongs to that FPGA device only. What's the use to keep tracking the usage reference with fpga_mgr_put/get function, or is it enough to increase/decrease dev reference count in fpga_mgr_register/unregister function? Thanks, Yi > > Signed-off-by: Alan Tull > --- > Documentation/fpga/fpga-mgr.txt | 19 ++++++++++++++++++- > 1 file changed, 18 insertions(+), 1 deletion(-) > > diff --git a/Documentation/fpga/fpga-mgr.txt b/Documentation/fpga/fpga-mgr.txt > index 78f197f..06d5d5b 100644 > --- a/Documentation/fpga/fpga-mgr.txt > +++ b/Documentation/fpga/fpga-mgr.txt > @@ -53,13 +53,26 @@ To get/put a reference to a FPGA manager: > struct fpga_manager *of_fpga_mgr_get(struct device_node *node); > struct fpga_manager *fpga_mgr_get(struct device *dev); > > -Given a DT node or device, get an exclusive reference to a FPGA manager. > +Given a DT node or device, get an reference to a FPGA manager. Pointer > +can be saved until you are ready to program the FPGA. > > void fpga_mgr_put(struct fpga_manager *mgr); > > Release the reference. > > > +To get exclusive control of a FPGA manager: > +------------------------------------------- > + > + int fpga_mgr_lock(struct fpga_magager *mgr); > + > +Call fpga_mgr_lock and verify that it returns 0 before attempting to > +program the FPGA. > + > + void fpga_mgr_unlock(struct fpga_magager *mgr); > + > +Call fpga_mgr_unlock when done programming the FPGA. > + > To register or unregister the low level FPGA-specific driver: > ------------------------------------------------------------- > > @@ -95,11 +108,13 @@ int ret; > > /* Get exclusive control of FPGA manager */ > struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node); > +ret = fpga_mgr_lock(mgr); > > /* Load the buffer to the FPGA */ > ret = fpga_mgr_buf_load(mgr, &info, buf, count); > > /* Release the FPGA manager */ > +fpga_mgr_unlock(mgr); > fpga_mgr_put(mgr); > > > @@ -124,11 +139,13 @@ int ret; > > /* Get exclusive control of FPGA manager */ > struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node); > +ret = fpga_mgr_lock(mgr); > > /* Get the firmware image (path) and load it to the FPGA */ > ret = fpga_mgr_firmware_load(mgr, &info, path); > > /* Release the FPGA manager */ > +fpga_mgr_unlock(mgr); > fpga_mgr_put(mgr); > >