From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laxman Dewangan Subject: Re: [PATCH V3 3/5] ARM: tegra:add aliases and DMA requestor for serial nodes of Tegra114 Date: Sat, 16 Mar 2013 00:33:12 +0530 Message-ID: <51437070.6080305@nvidia.com> References: <1363204194-19487-1-git-send-email-ldewangan@nvidia.com> <1363204194-19487-4-git-send-email-ldewangan@nvidia.com> <5140DB61.3090809@wwwdotorg.org> <514367F3.6040909@wwwdotorg.org> <51436BAE.9080206@nvidia.com> <51436F6C.1050901@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51436F6C.1050901-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On Saturday 16 March 2013 12:28 AM, Stephen Warren wrote: > On 03/15/2013 12:42 PM, Laxman Dewangan wrote: >> >> >> >> Simple uart driver use the uart clock divider and it is fine here. >> >> High speed uart driver uses the car register driver for better >> flexibility and better resolution. > OK, so I see that Tegra30 has an enhancement over Tegra20. However, > given your description, that enhancement is optional; a driver could > simply continue to use /just/ the in-UART divider, and ignore the CAR > divider, and still work just fine, albeit with (entirely > backwards-compatible) less accuracy than it might achieve if it used the > new feature. > > As such, I think it's correct to mark the device as actually being > compatible with all 3: 114 (precise HW model), 30 (base model w/ extra > divider), 20 (base model that's compatible, albeit ignoring extra features). > > That might be a bit excessive though, so I guess I'll just go with the > values in your patch. It'd be a good idea if you could post a follow-on > patch that updates the DT binding to explain this, and then removes the > comments from *.dtsi since this really should be explained in the > binding document not the .dtsi files, I think. > > At most, I'd expect to see the following in the .dtsi files: > > These nodes can either be compatible with nvidia,tegra114-uart, or > nvidia,tegra114-hsuart. See the bindings for details of the difference. Sure, I will post a patch for this.