From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Daney Subject: Re: [PATCH v6 4/5] MIPS: Octeon: Setup irq_domains for interrupts. Date: Fri, 09 Mar 2012 10:45:50 -0800 Message-ID: <4F5A4FDE.1030305@gmail.com> References: <1330563422-14078-1-git-send-email-ddaney.cavm@gmail.com> <1330563422-14078-5-git-send-email-ddaney.cavm@gmail.com> <4F50D7C2.7080204@gmail.com> <4F510B8E.3070201@cavium.com> <20120302190744.571E03E1C63@localhost> <4F511FB0.5070901@cavium.com> <4F527285.1020500@gmail.com> <4F52F90C.5060306@gmail.com> <20120309055704.465823E0901@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120309055704.465823E0901@localhost> Sender: linux-kernel-owner@vger.kernel.org To: Grant Likely Cc: David Daney , Rob Herring , David Daney , "linux-mips@linux-mips.org" , "ralf@linux-mips.org" , "devicetree-discuss@lists.ozlabs.org" , Rob Herring , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 03/08/2012 09:57 PM, Grant Likely wrote: > On Sat, 03 Mar 2012 21:09:32 -0800, David Daney wrote: >> On 03/03/2012 11:35 AM, Rob Herring wrote: >>> On 03/02/2012 01:29 PM, David Daney wrote: >>>> On 03/02/2012 11:07 AM, Grant Likely wrote: >>>>> +static void __init octeon_irq_set_ciu_mapping(unsigned int irq, >>>>> + unsigned int line, >>>>> + unsigned int bit, >>>>> + struct irq_domain *domain, >>>>> struct irq_chip *chip, >>>>> irq_flow_handler_t handler) >>>>> { >>>>> + struct irq_data *irqd; >>>>> union octeon_ciu_chip_data cd; >>>>> >>>>> irq_set_chip_and_handler(irq, chip, handler); >>>>> - >>>>> cd.l = 0; >>>>> cd.s.line = line; >>>>> cd.s.bit = bit; >>>>> >>>>> irq_set_chip_data(irq, cd.p); >>>>> octeon_irq_ciu_to_irq[line][bit] = irq; >>>>> + >>>>> + irqd = irq_get_irq_data(irq); >>>>> + irqd->hwirq = line<< 6 | bit; >>>>> + irqd->domain = domain; >>>>>>> I think the domain code will set these. >>>>>> It is my understanding that the domain code only does this for: >>>>>> >>>>>> o irq_domain_add_legacy() >>>>>> >>>>>> o irq_create_direct_mapping() >>>>>> >>>>>> o irq_create_mapping() >>>>>> >>>>>> We use none of those. So I do it here. >>>>>> >>>>>> If there is a better way, I am open to suggestions. >>>>> irq_create_mapping is called by irq_create_of_mapping() which is >>>>> in turn called by irq_of_parse_and-map(). irq_domain always >>>>> manages the hwirq and domain values. Driver code cannot manipulate >>>>> them manually. >>>>> >>>> I really must be missing something. >>>> >>>> Given: >>>> >>>> 1) I must have a mapping between hwirq and irq that I control so that >>>> non-OF code using the OCTEON_IRQ_* constants continues to work. >>> Those defines are what you need to work to get rid of. >> >> We are not starting from a blank slate here. There is a lot of in-tree >> code using these symbols. We cannot make them disappear with wishful >> thinking. >> >> The first step is a switch to irq_domains using the existing mappings. >> >> After we do that, I have patches to transition some drivers to use the >> OF mapping via irq_domains. After those are merged, we can work toward >> getting rid of OCTEON_IRQ_*. But I think it must be the last step in >> the process, not the first. >>> >>>> 2) irq_create_mapping() will allocate a random irq value if none is >>>> already assigned to the hwirq. >>>> >>>> Therefore: To avoid having random irq values assigned, I must manually >>>> assign them. >>>> >>> So you should be using legacy domain if you need to maintain fixed hwirq >>> to linux irq numbers. "linear" is a bit confusing as it doesn't mean >>> linear 1:1 irq number assignment, but linear search. >> >> My reading of Grant's code in linux-next directly contradicts this >> statement. There is no code in irqdomain.c, that I can see, that allows >> me to have an arbitrary mapping of irq<--> hwirq values. > > There are 4 kinds of mappings available; legacy, linear, radix and nomap. > Yes, I had discovered that. > Ignore nomap and radix; you don't want them. > > legacy maps a contiguous range of hwirq numbers to a contiguous range of > linux irq numbers. To preserve the exising #define mappings but still add > DT support, this is the one that you want. This is precisely the point that you and Rob seem to have missed in the last three or four back-and-forths about this. Probably I have not explained well enough why legacy will not work. We have three different interrupt controllers (although only one is currently in-tree). hwirq to irq mapping for them is more or less as follows: irq hwirqCIU hwirqCIU2 hwirqCIU3 ---------------------------------------------------------------------- OCTEON_IRQ_USB0 56 81 934562 OCTEON_IRQ_TWSI 45 224 100543 OCTEON_IRQ_UART0 34 228 4572 . . . Now what we notice here is that there is no possible 1:1 linearly increasing mapping possible for the irq and *all* three hwirq sets. We want a single binary that contains support for all three interrupt controllers, so the OCTEON_IRQ_* values have to be the same for all three interrupt controllers. Because of this, legacy mapping is *impossible*. Since the possible ranges of the hwirq values is very large and quite sparse, probably the radix mapping will be required. Also to support non-OF drivers and architecture specific code for the near future, I really think the existing IRQ values *must* be preserved. Therefore, as I said above, we need a way for my SOC/board code to specify the mapping. Perhaps we need to add an optional function to struct irq_domain_ops that would allow the default mapping to be overridden on a per irq_domain basis. Otherwise, I think I will have to keep poking into the internal irq_domain data structures to get the mappings I want. What do you think? David Daney