From mboxrd@z Thu Jan 1 00:00:00 1970 From: dwmw2@infradead.org (David Woodhouse) Date: Tue, 10 Sep 2013 16:05:49 +0100 Subject: [GIT PULL 0/3] ARM: SoC: Second round of changes for v3.12 In-Reply-To: References: <1378766555-9679-1-git-send-email-khilman@linaro.org> Message-ID: <1378825549.2627.316.camel@shinybook.infradead.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 2013-09-09 at 16:49 -0700, Linus Torvalds wrote: > > Ok. I still really despise the absolute incredible sh*t that is > non-discoverable buses, and I hope that ARM SoC hardware designers all > die in some incredibly painful accident. DT only does so much. Setting aside the inevitable whining from the emotionally-incontinent contingent that the above way of saying it will provoke, I'm not quite sure why you still haven't got over the fact that we have non-discoverable buses. In cost-sensitive products (and what *isn't* cost-sensitive these days), you really don't want to have to put an extra EEPROM on the board somewhere, just to describe what devices you've hung off which chip-select today. Storing that in the main flash is just *going* to happen, however much we'd like to think that devices should identify themselves cleanly and autonomously. And it isn't even something that a simple number like a PCI ID could manage. Peripherals are synthesisable components which vary *wildly*, with what are essentially #ifdefs in the VHDL. So a given controller could be seen with different FIFO depths, different numbers of queues, all kinds of variations. To cover the various permutations, you'd have to assign an *insane* number of PCI IDs. And then there's the various ways that you can connect blocks *together*... That's why we end up with the device-tree model which gives us a rich way to describe *this* instance of the hardware. If it wasn't device-tree, it'd have to be something *else*. >>From a software point of view it *isn't* nice, I agree. But you might as well be railing against the sunset, as far as I can tell. Not that any of this excuses crappy merges with lots of conflicts; but those don't seem to be an inexorable result of non-discoverable buses. -- dwmw2 -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/x-pkcs7-signature Size: 5745 bytes Desc: not available URL: