From mboxrd@z Thu Jan 1 00:00:00 1970 From: mirza.krak@gmail.com (Mirza Krak) Date: Fri, 22 Jul 2016 21:07:02 +0200 Subject: [RFC 3/6] dt/bindings: Add bindings for Tegra20/30 NOR bus driver In-Reply-To: <8e9cdefd-68d1-b788-92fb-b74aae1713c8@nvidia.com> References: <1468935397-11926-1-git-send-email-mirza.krak@gmail.com> <1468935397-11926-4-git-send-email-mirza.krak@gmail.com> <434561ec-510e-a3bf-c7b6-c961db299bd6@nvidia.com> <8e9cdefd-68d1-b788-92fb-b74aae1713c8@nvidia.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 2016-07-22 11:32 GMT+02:00 Jon Hunter : > > On 21/07/16 21:10, Mirza Krak wrote: >> 2016-07-21 11:56 GMT+02:00 Jon Hunter : >>> >>> I wonder if it is worth mentioning that the chip-select specified in the >>> "nvidia,config" prop should match that in the "ranges" prop unless you >>> have some external decoding logic to provide an external chip-select. >>> Which raises a question, what does the chip-select in the ranges >>> actually represent? I am not sure if there is a common practice here for >>> device tree when boards have external logic to provide additional >>> chip-selects. I am sure this is quite common. >> >> I do not understand why CS pin setting in nvidia,config need to match >> the "ranges" prop? Other then maybe cosmetics. > > Yes it would be cosmetic. That said, I even wonder if CS needs to be > exposed at all given that they all map to the same CPU address space. > Couldn't your binding for the CAN devices be as follows? > > nor at 70009000 { > ... > > can at 48000000 { > ... > }; > > can at 48040000 { > ... > }; > }; This has also crossed my mind, maybe just get rid of the "ranges" prop and do like you have above. But then again I do not know what is preferred so I went with "ranges" prop initially. > > Problem is if you did have devices on different chip-selects then how > would these be handled? They could not point to the same physical > address. I am not sure if there is a way to do that in DT? Having trouble following your though here. We do not have "different" chip-selects? Best Regards Mirza