From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [Intel-gfx] [PATCH 1/3] pinctrl: Intel: add RX invertion config Date: Thu, 17 Mar 2016 17:14:24 +0200 Message-ID: <874mc5uofj.fsf@intel.com> References: <1457715962-108484-1-git-send-email-qipeng.zha@intel.com> <20160311093856.GN1796@lahna.fi.intel.com> <0DD381DBF8F68D419C32ACFCEB28EB2521D1032C@SHSMSX101.ccr.corp.intel.com> <20160314085002.GY1796@lahna.fi.intel.com> <0DD381DBF8F68D419C32ACFCEB28EB2521D10643@SHSMSX101.ccr.corp.intel.com> <0DD381DBF8F68D419C32ACFCEB28EB2521D10AC2@SHSMSX101.ccr.corp.intel.com> <20160316133412.GN14170@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mga03.intel.com ([134.134.136.65]:45314 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030970AbcCQPOg (ORCPT ); Thu, 17 Mar 2016 11:14:36 -0400 In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Linus Walleij , Daniel Vetter , Felipe Balbi , "linux-usb@vger.kernel.org" Cc: "Westerberg, Mika" , Hans Holmberg , "linux-gpio@vger.kernel.org" , DRI Development , "Zha, Qipeng" , Daniel Vetter , Intel Graphics Development , "Zheng, Qi" On Thu, 17 Mar 2016, Linus Walleij wrote: > On Wed, Mar 16, 2016 at 2:34 PM, Daniel Vetter wrote: >> On Wed, Mar 16, 2016 at 01:27:49PM +0100, Linus Walleij wrote: > >>> - What is a HPD interrupt? >> >> hotplug interrupt, fires when you plug in a cable. >> >>> - What is a Type-C DP HPD? >> >> usb type C connector can multiplex both DisplayPort and USB, you need to >> renegotiate the lane splitting every time the sink changes, i.e. on each >> hotplug. > > OK I understand, thanks a lot! > >>> - Again why can't you just use a notifier or function call? >> >> Because windows sucks, hence all that coordination happens through hw >> forwarded interrupts and magic registers. Same horror story on the sound >> side, where the sound driver needs to know what kind of PCM stream the >> monitor can take. It's hilarious. Except when they screw up the design and >> then need to fake parts of it in software. > > So the story is something like that these IRQs have been put into > hardware in order to compensate for flaws in Windows device driver > model, I see. > > If there are such special registers in some hardware I guess I'm all for > implementing some generic quirk in gpiolib for people who need to > software-trigger GPIO IRQs. Could be good for testing too, as there > are such registers in ARMs PL061 GPIO controller for test, just so as > to simulate a GPIO IRQ. > > gpiod_trig_irq() would work with me, I'm happy to support whatever > the GPIO hardware can do usually. > >> In sound we've switched over to a proper sw interface, and we tie the >> different parts (drm graphics driver and alsa snd driver) using the >> component.c framework. > > Hm is that solution or something similar proper for USB connector > as well I wonder... I was thinking about just adding $random_notifier > but maybe that is a bit ugly :/ > >>> What is VPG? Now it seems Intel's internal organization is being used as >>> part of the argument to get this change in and that makes me a bit >>> annoyed. > (...) >> There was chat of usb type C support for forever, but I was always >> promised that we don't need any interactions on the sw side and it's all >> magic in hw. There hasn't been any real design discussions in the open >> source group. VPG is the hw/windows group and generally comes up with >> "interesting" designs not suitable for upstream. >> >> Feel free to just nack this stuff, and please cc intel-gfx/dri-devel in >> the future (since I tend to ignore everything that's not cc'ed to mailing >> lists I don't care about, even when I'm on cc personally). I've added them >> all to cc. > > Thanks a lot Daniel, I understand better now. I'm not really against > adding this "interesting" workaround if that is how Windows works, > we usually have to go by their standards. From the GPIO point > of view it is OK, just something the GPIO can do. I would be more > worried about what the USB PHY maintainer (Felipe) is going to say > about this. Adding Felipe's current address. Considering the new domain part of the address, I'm hopeful we can sort this out. ;) BR, Jani. > > Yours, > Linus Walleij > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Jani Nikula, Intel Open Source Technology Center