Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965060AbcKNXA4 (ORCPT ); Mon, 14 Nov 2016 18:00:56 -0500 Received: from us01smtprelay-2.synopsys.com ([198.182.60.111]:36106 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937878AbcKNXAx (ORCPT ); Mon, 14 Nov 2016 18:00:53 -0500 Subject: Re: [PATCH 1/2] usb: dwc2: add amcc,dwc-otg support To: Christian Lamparter , John Youn References: <1546251.ssrfyj8Loe@debian64> <3741942.Du5DzKuQeQ@debian64> CC: "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , Mark Rutland , Rob Herring , Greg Kroah-Hartman , Felipe Balbi From: John Youn Message-ID: Date: Mon, 14 Nov 2016 15:00:51 -0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <3741942.Du5DzKuQeQ@debian64> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.9.139.160] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7425 Lines: 174 On 11/11/2016 3:12 PM, Christian Lamparter wrote: > On Friday, November 11, 2016 2:20:42 PM CET John Youn wrote: >> On 11/11/2016 2:05 PM, Christian Lamparter wrote: >>> On Friday, November 11, 2016 1:22:16 PM CET John Youn wrote: >>>> On 11/11/2016 12:59 PM, Christian Lamparter wrote: >>>>> This patch adds support for the "amcc,usb-otg" device >>>>> which is found in the PowerPC Canyonlands' dts. >>>>> >>>>> The device definition was added by: >>>>> commit c89b3458d8cc ("powerpc/44x: Add USB DWC DTS entry to Canyonlands board")' >>>>> but without any driver support as the dwc2 driver wasn't >>>>> available at that time. >>>>> >>>>> Note: The system can't use the generic "snps,dwc2" compatible >>>>> because of the special ahbcfg configuration. The default >>>>> GAHBCFG_HBSTLEN_INCR4 of snps,dwc2 can cause a system hang >>>>> when the USB and SATA is used concurrently. >>>> >>>> I don't want to add any more of these param structures to the driver >>>> unless really necessary. We're trying to remove usage of them in favor >>>> of using auto-detected defaults and device properties to override >>>> them. >>> Ok, thanks. I think that would work. I've attached an updated patch. >>> Can it be applied/queued now? Or do you want me to resent it later? >>> >>>> The AHB Burst is actually one of the ones we were going to do next >>>> because our platform also doesn't work well with INCR4. In fact I'm >>>> thinking of making the default INCR. >>> Is that actually possible to change the default still? This would >>> require to re-evaluate all existing archs/platforms that use >>> "snps,dwc2" for INCR16 compatibility. >> >> INCR, not INCR16, but you're right, so we may not change it even >> though though INCR is usually the right choice over INCR4. > What about making a device-tree property? Yes, that's what I meant. I'll send a change for this shortly. > > Recommended properties: > - g-ahb-bursts : specifies the ahb bursts length, should be one of > "single", "INCRx", "INCR4", "INCR8", or "INCR16". If not specified > the safer but inefficient "INCR4" is used. The optimal setting is > "INCRx". > > Would this work? If so, I can make a patch over the weekend. >> Anyways, with the binding, can't you just set the compatible string to >> snps,dwc2? > > Ah, let me explain. I had a discussion with Mark Rutland and Rob Herring > a while back about device-tree bindings. > > They made it very clear to me, that they don't want any generic "catch all > compatible" strings: > > "Bindings should be for hardware (either specific device models, or for > classes), and not for Linux drivers. The latter is subject to arbitrary > changes while the former is not, as old hardware continues to exist and > does not change while drivers get completely reworked." [0] > > Furthermore, this is an existing binding in kernel's canyonlands.dts [1] > and this binding can't be easily changed. Rob Herring explained this in > the context of the "basic-mmio-gpio" patch [2] when I was editing the dts > to make them work with the changes I made: > > "You can't remove the old drivers as they are needed to work with > old dtbs, so there is no gain. > > You would need to match on existing compatibles such as > moxa,moxart-gpio and provide a match data struct that has all the info > you are adding here (e.g. data register offset). Then additionally you > could add "basic-mmio-gpio" (I would drop "basic" part) and the > additional data associated with it. But it has to be new properties, > not changing properties. Changing the reg values doesn't work." > > So, for this to work with the existing canyonlands.dts, I need to have > the "amcc,dwc-otg" compatible string. Ok, if that's the case. But still a bit confused as to what driver was working with it before since the binding was not defined for dwc2. > > Of course, it would be great to hear from Rob Herring and/or Mark Rutland > about this case. > > Regards, > Christian > > [0] > [1] > [2] > > >>> >>> From what I can tell based would be: >>> bcm11351, bcm21664, bcm23550, exynos3250, stm32f429, rk3xxx, >>> stratix10, meson-gxbb, rt3050 and some Altera FPGAs. >>> >>>> If that's all you need then a devicetree binding should be enough >>>> right? >>> Yes. The device is working fine so far. >>> >>> Regards, >>> Christian >>> >>> --- >>> From 70dd4be016b89655a56bc8260f04683b50f07644 Mon Sep 17 00:00:00 2001 >>> From: Christian Lamparter >>> Date: Sun, 6 Nov 2016 00:39:24 +0100 >>> Subject: [PATCH] usb: dwc2: add amcc,dwc-otg support >>> >>> This patch adds support for the "amcc,usb-otg" device >>> which is found in the PowerPC Canyonlands' dts. >>> >>> The device definition was added by: >>> commit c89b3458d8cc ("powerpc/44x: Add USB DWC DTS entry to Canyonlands board")' >>> but without any driver support as the dwc2 driver wasn't >>> available at that time. >>> >>> Note: The system can't use the generic "snps,dwc2" compatible >>> because of the special ahbcfg configuration. The default >>> GAHBCFG_HBSTLEN_INCR4 of snps,dwc2 can cause a system hang >>> when the USB and SATA is used concurrently. >>> >>> Cc: Felipe Balbi >>> Cc: John Youn >>> Signed-off-by: Christian Lamparter >>> --- >>> v1->v2: >>> - moved definitons to params.c >>> - removed dma_enable / host_dma parameter >>> - added dma_desc_fs_enable parameter >>> v2->v3: >>> - removed parameters >>> >>> Please queue this patch until GAHBCFG_HBSTLEN_INCR16 is the default >>> for ahbcfg. >>> --- >>> Documentation/devicetree/bindings/usb/dwc2.txt | 1 + >>> drivers/usb/dwc2/params.c | 1 + >>> 2 files changed, 2 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/usb/dwc2.txt b/Documentation/devicetree/bindings/usb/dwc2.txt >>> index 10a2a4b..6ccfe85 100644 >>> --- a/Documentation/devicetree/bindings/usb/dwc2.txt >>> +++ b/Documentation/devicetree/bindings/usb/dwc2.txt >>> @@ -12,6 +12,7 @@ Required properties: >>> - "lantiq,xrx200-usb": The DWC2 USB controller instance in Lantiq XRX SoCs; >>> - "amlogic,meson8b-usb": The DWC2 USB controller instance in Amlogic Meson8b SoCs; >>> - "amlogic,meson-gxbb-usb": The DWC2 USB controller instance in Amlogic S905 SoCs; >>> + - "amcc,dwc-otg": The DWC2 USB controller instance in AMCC Canyonlands 460EX SoCs; >>> - snps,dwc2: A generic DWC2 USB controller with default parameters. >>> - reg : Should contain 1 register range (address and length) >>> - interrupts : Should contain 1 interrupt >>> diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c >>> index 64d5c66..9506ab0 100644 >>> --- a/drivers/usb/dwc2/params.c >>> +++ b/drivers/usb/dwc2/params.c >>> @@ -239,6 +239,7 @@ const struct of_device_id dwc2_of_match_table[] = { >>> { .compatible = "samsung,s3c6400-hsotg", .data = NULL}, >>> { .compatible = "amlogic,meson8b-usb", .data = ¶ms_amlogic }, >>> { .compatible = "amlogic,meson-gxbb-usb", .data = ¶ms_amlogic }, >>> + { .compatible = "amcc,dwc-otg", .data = NULL }, >>> {}, >>> }; >>> MODULE_DEVICE_TABLE(of, dwc2_of_match_table); >>> For dwc2 part: Acked-by: John Youn Regards, John