Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755206Ab3HWQ24 (ORCPT ); Fri, 23 Aug 2013 12:28:56 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:58293 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754217Ab3HWQ2y (ORCPT ); Fri, 23 Aug 2013 12:28:54 -0400 Message-ID: <52178D98.8020202@ti.com> Date: Fri, 23 Aug 2013 21:58:08 +0530 From: Sekhar Nori User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: Santosh Shilimkar CC: Sricharan R , Rajendra Nayak , Nishanth Menon , Russell King - ARM Linux , "linux-doc@vger.kernel.org" , Tony Lindgren , Linus Walleij , "linux-kernel@vger.kernel.org" , Felipe Balbi , Grant Likely , Thomas Gleixner , Linux-OMAP , "devicetree-discuss@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH 1/3] misc: Add crossbar driver References: <51E83A4F.5080904@ti.com> <51ED2385.60108@ti.com> <51ED5C66.1010407@ti.com> <51EFFBE1.4090505@ti.com> <51F0031B.1050307@ti.com> <51F00530.9090703@ti.com> <51F02069.3050207@ti.com> <51F0223E.4050008@ti.com> <51F0240F.3050507@ti.com> <20130813081003.GU7656@atomide.com> <520A02BA.4090805@ti.com> <520D398D.9040806@ti.com> <520D44C5.6080205@ti.com> <5215F6F6.9060703@ti.com> <5216E966.5020902@ti.com> <5216FD0C.3090709@ti.com> <521702E2.5000102@ti.com> <521706D9.9070001@ti.com> <521719D8.7060506@ti.com> <521765DC.2000609@ti.com> In-Reply-To: <521765DC.2000609@ti.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3674 Lines: 68 On 8/23/2013 7:08 PM, Santosh Shilimkar wrote: > On Friday 23 August 2013 04:14 AM, Sekhar Nori wrote: >> On Friday 23 August 2013 12:23 PM, Sricharan R wrote: >>> On Friday 23 August 2013 12:06 PM, Sekhar Nori wrote: >>>> On Friday 23 August 2013 11:41 AM, Sricharan R wrote: >>>>> Hi, >>>>> On Friday 23 August 2013 10:17 AM, Rajendra Nayak wrote: >>>>>> On Thursday 22 August 2013 05:03 PM, Sricharan R wrote: >>>>>>> maps crossbar number<-> to interrupt number and >>>>>>> calls request_irq(int_no, crossbar_handler,..) >>>>>> So will this mapping happen based on some data passed from DT or >>>>>> just based on whats available when the device does a request_irq()? >>>>>> >>>>>> If its based on whats available then I see an issue when you need >>>>>> to remap something thats already mapped by default (and not used) >>>>>> since you run out of all free ones. >>>>> Yes, when done based on what is available then there is a >>>>> problem when we run out of free ones because we do not >>>>> know which one to replace. I was thinking of something like >>>>> this, >>>>> 1) DT would give a list of all free ones, and also if some are >>>>> mapped as default and not used, mark those also as free. >>>>> >>>>> 2) While mapping see if it has a default mapping and use it. >>>>> otherwise, pick from free list. >>>> Since the entire DT is available to you at boot time, you should be able >>>> to find each node where interrupt-parent = <&crossbar> and then allocate >>>> one of 0-160 GIC interrupt numbers for that node, no? Where would there >>>> be a need for default mapping and remapping? From one the mails in the >>>> thread the crossbar is completely flexible - any of the 320 crossbar >>>> interrupts can be mapped to any of the 160 GIC interrupts. >>>> >>>> Any GIC interrupts left after this boot-time scan can be added to an >>>> unused list for use with runtime DT fragments (when that support comes). >>>> >>>> Sorry if I misunderstood, but above proposal sounds like maintaining a >>>> separate free interrupt lines list in DT. That will quickly go out of sync. >>> Say, peripheral x uses crossbar 1 and specifies this in DT. >>> During boot crossbar 1 gets mapped int 10. So if by default >>> some other crossbar has its interrupt mapped to 10, >>> then it should be removed. Instead clear all crossbar registers >>> once and mark all as free, then allocate only during request. >>> Correct ?. In this the free no need to maintain any list. >> >> Right, so in my suggestion there is nothing like a "default mapping" and >> entire 160 GIC interrupt number space is up for grabs. I think this will >> be much simpler to write and maintain. >> >> If you really want to maintain default mapping as far as possible, you >> can do two passes on the crossbar interrupt numbers requested. Once to >> assign the default map - for numbers less that 160 - and then look at >> the free GIC interrupt slots and use those for numbers greater than 160. >> > The whole point we are moving to domain is not have any default > mapping(connection done) at DT level. Rather DT only specifies the > peripherals and their cross-bar connection ID(i.e cross-bar IRQ line). > This will be the driver input as a IRQ line from DT. The cross-bar > driver needs to map any of the free list available on *request* only. Right, the mapping can be done on request. That will be cleaner. Thanks, Sekhar -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/