From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: st_fdma: Firmware filename in DT? Date: Mon, 07 Sep 2015 14:41:17 +0200 Message-ID: <5009480.9u9jyfIQDy@wuerfel> References: <20150903144944.GC7093@griffinp-ThinkPad-X1-Carbon-2nd> <201509051058.54229.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: devicetree-spec-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Warner Losh Cc: Lee Jones , Peter Griffin , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Vinod Koul , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Maxime Coquelin , Patrice Chotard , Ludovic Barre , "devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org On Saturday 05 September 2015 15:06:35 Warner Losh wrote: > On Sat, Sep 5, 2015 at 2:58 AM, Arnd Bergmann wrote: > > On Friday 04 September 2015, Warner Losh wrote: > > I understood what you were proposing. It wasn't a lack of understanding > that lead me to the opinion that it was a horrible policy. Despite your > lengthy explanation, you did nothing to address the very simple and common > use case of having identical hardware that none-the-less needs different > firmware which was my basis of the horrible brand I put on this policy. You must be thinking of different examples of firmware files than I am. We have tons of drivers that need firmware, and the reasons for picking a particular file over another alternative tend to be slightly different (most of the time, you just want the latest version). Can you name a specific example you are thinking of where you want different firmware to be loaded on systems with identical hardware? > Also, firmware comes from vendors generally named something other > than FDT compat strings. Renaming firmware generally is also a > horrible policy that most shops frown on. It hampers traceability from > a deployed system back to the sources, for one and introduces one > more place for an 'oops' rename to go undetected until the firmware > is deployed. Most firmware that I can think of does not even come as a file in the format that Linux wants, often there is some vendor source code with firmware in a header file, or you dissect a windows binary driver to pull out the right bits. The file name gets fixed at the point at which the binary is included in the linux-firmware git tree. > So there needs to be a standardized way to augment local policy > to say 'the firmware you need for this node so that the system behaves > as expect in the DT is Y.' Why is that even something that is known by the boot loader? If the boot loader just knows what hardware you have, but a particular instance requires some other device firmware, that sounds like the system administrator would just put the special firmware file in a known location on the local file system (preferably not the same file name as the generic one). Arnd