From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10DB7C433F5 for ; Mon, 22 Nov 2021 21:51:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235954AbhKVVyF (ORCPT ); Mon, 22 Nov 2021 16:54:05 -0500 Received: from sibelius.xs4all.nl ([83.163.83.176]:61056 "EHLO sibelius.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235323AbhKVVyA (ORCPT ); Mon, 22 Nov 2021 16:54:00 -0500 Received: from localhost (bloch.sibelius.xs4all.nl [local]) by bloch.sibelius.xs4all.nl (OpenSMTPD) with ESMTPA id fa3b4a34; Mon, 22 Nov 2021 22:50:48 +0100 (CET) Date: Mon, 22 Nov 2021 22:50:48 +0100 (CET) From: Mark Kettenis To: Marc Zyngier Cc: pali@kernel.org, luca@lucaceresoli.net, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, kernel-team@android.com, alyssa@rosenzweig.io, lorenzo.pieralisi@arm.com, bhelgaas@google.com, joey.gouly@arm.com In-Reply-To: <87zgpw5jza.wl-maz@kernel.org> (message from Marc Zyngier on Mon, 22 Nov 2021 14:43:37 +0000) Subject: Re: [PATCH v2] PCI: apple: Follow the PCIe specifications when resetting the port References: <20211122104156.518063-1-maz@kernel.org> <20211122120347.6qyiycqqjkgqvtta@pali> <87zgpw5jza.wl-maz@kernel.org> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Message-ID: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Date: Mon, 22 Nov 2021 14:43:37 +0000 > From: Marc Zyngier > > On Mon, 22 Nov 2021 12:03:47 +0000, > Pali Rohár wrote: > > > > On Monday 22 November 2021 10:41:56 Marc Zyngier wrote: > > > While the Apple PCIe driver works correctly when directly booted > > > from the firmware, it fails to initialise when the kernel is booted > > > from a bootloader using PCIe such as u-boot. > > > > > > That's beacuse we're missing a proper reset of the port (we only > > > clear the reset, but never assert it). > > > > > > The PCIe spec requirements are two-fold: > > > > > > - #PERST must be asserted before setting up the clocks, and > > > stay asserted for at least 100us (Tperst-clk). > > > > > > - Once #PERST is deasserted, the OS must wait for at least 100ms > > > "from the end of a Conventional Reset" before we can start talking > > > to the devices > > > > > > Implementing this results in a booting system. > > > > > > Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up") > > > Signed-off-by: Marc Zyngier > > > Cc: Alyssa Rosenzweig > > > Cc: Lorenzo Pieralisi > > > Cc: Bjorn Helgaas > > > Cc: Pali Rohár > > > > Looks good, but see comment below. > > > > Acked-by: Pali Rohár > > Thanks for that. > > > > > > --- > > > drivers/pci/controller/pcie-apple.c | 10 ++++++++++ > > > 1 file changed, 10 insertions(+) > > > > > > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c > > > index 1bf4d75b61be..957960a733c4 100644 > > > --- a/drivers/pci/controller/pcie-apple.c > > > +++ b/drivers/pci/controller/pcie-apple.c > > > @@ -539,13 +539,23 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie, > > > > > > rmw_set(PORT_APPCLK_EN, port->base + PORT_APPCLK); > > > > > > + /* Engage #PERST before setting up the clock */ > > > + gpiod_set_value(reset, 0); > > > + > > > ret = apple_pcie_setup_refclk(pcie, port); > > > if (ret < 0) > > > return ret; > > > > > > + /* The minimal Tperst-clk value is 100us (PCIe CMS r2.0, 2.6.2) */ > > > + usleep_range(100, 200); > > > + > > > + /* Deassert #PERST */ > > > rmw_set(PORT_PERST_OFF, port->base + PORT_PERST); > > > gpiod_set_value(reset, 1); > > > > + Luca > > > > Just one comment. PERST# (PCIe Reset) is active-low signal. De-asserting > > means to really set value to 1. > > > > But there was a discussion that de-asserting should be done by call: > > gpiod_set_value(reset, 0); > > > > https://lore.kernel.org/linux-pci/51be082a-ff10-8a19-5648-f279aabcac51@lucaceresoli.net/ > > > > Could we make this new pcie-apple.c driver to use gpiod_set_value(reset, 0) > > for de-asserting, like in other drivers? > > I guess it depends whether you care about the assertion or the signal > itself. I think we may have a bug in the way the GPIOs are handled at > the moment, as it makes no difference whether I register the GPIO are > active high or active low... That's unfortunate. But maybe that's an opportunity to fix the devicetree to use GPIO_ACTIVE_LOW for these GPIOs? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B1F09C433F5 for ; Mon, 22 Nov 2021 21:52:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Message-ID:MIME-version:References: Subject:In-Reply-To:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=NiH6NyZC2GNHj4qjE7yp28m308c6jky4/9TwI7bk8Bo=; b=opEeLOaQsnVfTV DLKgfB/2e1XOnlrLSsefQq2BUJuyWVRy9OTcFnb51NAsLTEaRVwM8RlQugihL8EUgSBJMFXtiGyOa Q6pjdSxJw1SnZuXUwPiNYpH9RRmm+ijFzc6s5OeB9bu5HkmVAeTl1tdETgXwcZNQTezTXtKyszr7y LNbtsVEg54he+Zf7em+MKa+0gmIDS2RzBpSofSe761VvALdOb3zLvjr2tXVZgasaFjlwqqeZjSgQH 2slUvHt5xMDh+3sB4ejHSL+rkuxS+Rogr5lFHhSlxHQeOPdYeS6Drrd8yrNZsR4DLsmaeXtbPl2Ke 97XnTJ0Tlz7jaOL7LrwA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mpHDC-0004em-Um; Mon, 22 Nov 2021 21:50:55 +0000 Received: from sibelius.xs4all.nl ([83.163.83.176]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mpHD8-0004eR-PP for linux-arm-kernel@lists.infradead.org; Mon, 22 Nov 2021 21:50:52 +0000 Received: from localhost (bloch.sibelius.xs4all.nl [local]) by bloch.sibelius.xs4all.nl (OpenSMTPD) with ESMTPA id fa3b4a34; Mon, 22 Nov 2021 22:50:48 +0100 (CET) Date: Mon, 22 Nov 2021 22:50:48 +0100 (CET) From: Mark Kettenis To: Marc Zyngier Cc: pali@kernel.org, luca@lucaceresoli.net, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, kernel-team@android.com, alyssa@rosenzweig.io, lorenzo.pieralisi@arm.com, bhelgaas@google.com, joey.gouly@arm.com In-Reply-To: <87zgpw5jza.wl-maz@kernel.org> (message from Marc Zyngier on Mon, 22 Nov 2021 14:43:37 +0000) Subject: Re: [PATCH v2] PCI: apple: Follow the PCIe specifications when resetting the port References: <20211122104156.518063-1-maz@kernel.org> <20211122120347.6qyiycqqjkgqvtta@pali> <87zgpw5jza.wl-maz@kernel.org> MIME-version: 1.0 Message-ID: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211122_135051_192549_A5753D3D X-CRM114-Status: GOOD ( 31.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org PiBEYXRlOiBNb24sIDIyIE5vdiAyMDIxIDE0OjQzOjM3ICswMDAwCj4gRnJvbTogTWFyYyBaeW5n aWVyIDxtYXpAa2VybmVsLm9yZz4KPiAKPiBPbiBNb24sIDIyIE5vdiAyMDIxIDEyOjAzOjQ3ICsw MDAwLAo+IFBhbGkgUm9ow6FyIDxwYWxpQGtlcm5lbC5vcmc+IHdyb3RlOgo+ID4gCj4gPiBPbiBN b25kYXkgMjIgTm92ZW1iZXIgMjAyMSAxMDo0MTo1NiBNYXJjIFp5bmdpZXIgd3JvdGU6Cj4gPiA+ IFdoaWxlIHRoZSBBcHBsZSBQQ0llIGRyaXZlciB3b3JrcyBjb3JyZWN0bHkgd2hlbiBkaXJlY3Rs eSBib290ZWQKPiA+ID4gZnJvbSB0aGUgZmlybXdhcmUsIGl0IGZhaWxzIHRvIGluaXRpYWxpc2Ug d2hlbiB0aGUga2VybmVsIGlzIGJvb3RlZAo+ID4gPiBmcm9tIGEgYm9vdGxvYWRlciB1c2luZyBQ Q0llIHN1Y2ggYXMgdS1ib290Lgo+ID4gPiAKPiA+ID4gVGhhdCdzIGJlYWN1c2Ugd2UncmUgbWlz c2luZyBhIHByb3BlciByZXNldCBvZiB0aGUgcG9ydCAod2Ugb25seQo+ID4gPiBjbGVhciB0aGUg cmVzZXQsIGJ1dCBuZXZlciBhc3NlcnQgaXQpLgo+ID4gPiAKPiA+ID4gVGhlIFBDSWUgc3BlYyBy ZXF1aXJlbWVudHMgYXJlIHR3by1mb2xkOgo+ID4gPiAKPiA+ID4gLSAjUEVSU1QgbXVzdCBiZSBh c3NlcnRlZCBiZWZvcmUgc2V0dGluZyB1cCB0aGUgY2xvY2tzLCBhbmQKPiA+ID4gICBzdGF5IGFz c2VydGVkIGZvciBhdCBsZWFzdCAxMDB1cyAoVHBlcnN0LWNsaykuCj4gPiA+IAo+ID4gPiAtIE9u Y2UgI1BFUlNUIGlzIGRlYXNzZXJ0ZWQsIHRoZSBPUyBtdXN0IHdhaXQgZm9yIGF0IGxlYXN0IDEw MG1zCj4gPiA+ICAgImZyb20gdGhlIGVuZCBvZiBhIENvbnZlbnRpb25hbCBSZXNldCIgYmVmb3Jl IHdlIGNhbiBzdGFydCB0YWxraW5nCj4gPiA+ICAgdG8gdGhlIGRldmljZXMKPiA+ID4gCj4gPiA+ IEltcGxlbWVudGluZyB0aGlzIHJlc3VsdHMgaW4gYSBib290aW5nIHN5c3RlbS4KPiA+ID4gCj4g PiA+IEZpeGVzOiAxZTMzODg4ZmJlNDQgKCJQQ0k6IGFwcGxlOiBBZGQgaW5pdGlhbCBoYXJkd2Fy ZSBicmluZy11cCIpCj4gPiA+IFNpZ25lZC1vZmYtYnk6IE1hcmMgWnluZ2llciA8bWF6QGtlcm5l bC5vcmc+Cj4gPiA+IENjOiBBbHlzc2EgUm9zZW56d2VpZyA8YWx5c3NhQHJvc2VuendlaWcuaW8+ Cj4gPiA+IENjOiBMb3JlbnpvIFBpZXJhbGlzaSA8bG9yZW56by5waWVyYWxpc2lAYXJtLmNvbT4K PiA+ID4gQ2M6IEJqb3JuIEhlbGdhYXMgPGJoZWxnYWFzQGdvb2dsZS5jb20+Cj4gPiA+IENjOiBQ YWxpIFJvaMOhciA8cGFsaUBrZXJuZWwub3JnPgo+ID4gCj4gPiBMb29rcyBnb29kLCBidXQgc2Vl IGNvbW1lbnQgYmVsb3cuCj4gPiAKPiA+IEFja2VkLWJ5OiBQYWxpIFJvaMOhciA8cGFsaUBrZXJu ZWwub3JnPgo+IAo+IFRoYW5rcyBmb3IgdGhhdC4KPiAKPiA+IAo+ID4gPiAtLS0KPiA+ID4gIGRy aXZlcnMvcGNpL2NvbnRyb2xsZXIvcGNpZS1hcHBsZS5jIHwgMTAgKysrKysrKysrKwo+ID4gPiAg MSBmaWxlIGNoYW5nZWQsIDEwIGluc2VydGlvbnMoKykKPiA+ID4gCj4gPiA+IGRpZmYgLS1naXQg YS9kcml2ZXJzL3BjaS9jb250cm9sbGVyL3BjaWUtYXBwbGUuYyBiL2RyaXZlcnMvcGNpL2NvbnRy b2xsZXIvcGNpZS1hcHBsZS5jCj4gPiA+IGluZGV4IDFiZjRkNzViNjFiZS4uOTU3OTYwYTczM2M0 IDEwMDY0NAo+ID4gPiAtLS0gYS9kcml2ZXJzL3BjaS9jb250cm9sbGVyL3BjaWUtYXBwbGUuYwo+ ID4gPiArKysgYi9kcml2ZXJzL3BjaS9jb250cm9sbGVyL3BjaWUtYXBwbGUuYwo+ID4gPiBAQCAt NTM5LDEzICs1MzksMjMgQEAgc3RhdGljIGludCBhcHBsZV9wY2llX3NldHVwX3BvcnQoc3RydWN0 IGFwcGxlX3BjaWUgKnBjaWUsCj4gPiA+ICAKPiA+ID4gIAlybXdfc2V0KFBPUlRfQVBQQ0xLX0VO LCBwb3J0LT5iYXNlICsgUE9SVF9BUFBDTEspOwo+ID4gPiAgCj4gPiA+ICsJLyogRW5nYWdlICNQ RVJTVCBiZWZvcmUgc2V0dGluZyB1cCB0aGUgY2xvY2sgKi8KPiA+ID4gKwlncGlvZF9zZXRfdmFs dWUocmVzZXQsIDApOwo+ID4gPiArCj4gPiA+ICAJcmV0ID0gYXBwbGVfcGNpZV9zZXR1cF9yZWZj bGsocGNpZSwgcG9ydCk7Cj4gPiA+ICAJaWYgKHJldCA8IDApCj4gPiA+ICAJCXJldHVybiByZXQ7 Cj4gPiA+ICAKPiA+ID4gKwkvKiBUaGUgbWluaW1hbCBUcGVyc3QtY2xrIHZhbHVlIGlzIDEwMHVz IChQQ0llIENNUyByMi4wLCAyLjYuMikgKi8KPiA+ID4gKwl1c2xlZXBfcmFuZ2UoMTAwLCAyMDAp Owo+ID4gPiArCj4gPiA+ICsJLyogRGVhc3NlcnQgI1BFUlNUICovCj4gPiA+ICAJcm13X3NldChQ T1JUX1BFUlNUX09GRiwgcG9ydC0+YmFzZSArIFBPUlRfUEVSU1QpOwo+ID4gPiAgCWdwaW9kX3Nl dF92YWx1ZShyZXNldCwgMSk7Cj4gPiAKPiA+ICsgTHVjYQo+ID4gCj4gPiBKdXN0IG9uZSBjb21t ZW50LiBQRVJTVCMgKFBDSWUgUmVzZXQpIGlzIGFjdGl2ZS1sb3cgc2lnbmFsLiBEZS1hc3NlcnRp bmcKPiA+IG1lYW5zIHRvIHJlYWxseSBzZXQgdmFsdWUgdG8gMS4KPiA+IAo+ID4gQnV0IHRoZXJl IHdhcyBhIGRpc2N1c3Npb24gdGhhdCBkZS1hc3NlcnRpbmcgc2hvdWxkIGJlIGRvbmUgYnkgY2Fs bDoKPiA+ICAgZ3Bpb2Rfc2V0X3ZhbHVlKHJlc2V0LCAwKTsKPiA+IAo+ID4gaHR0cHM6Ly9sb3Jl Lmtlcm5lbC5vcmcvbGludXgtcGNpLzUxYmUwODJhLWZmMTAtOGExOS01NjQ4LWYyNzlhYWJjYWM1 MUBsdWNhY2VyZXNvbGkubmV0Lwo+ID4gCj4gPiBDb3VsZCB3ZSBtYWtlIHRoaXMgbmV3IHBjaWUt YXBwbGUuYyBkcml2ZXIgdG8gdXNlIGdwaW9kX3NldF92YWx1ZShyZXNldCwgMCkKPiA+IGZvciBk ZS1hc3NlcnRpbmcsIGxpa2UgaW4gb3RoZXIgZHJpdmVycz8KPiAKPiBJIGd1ZXNzIGl0IGRlcGVu ZHMgd2hldGhlciB5b3UgY2FyZSBhYm91dCB0aGUgYXNzZXJ0aW9uIG9yIHRoZSBzaWduYWwKPiBp dHNlbGYuIEkgdGhpbmsgd2UgbWF5IGhhdmUgYSBidWcgaW4gdGhlIHdheSB0aGUgR1BJT3MgYXJl IGhhbmRsZWQgYXQKPiB0aGUgbW9tZW50LCBhcyBpdCBtYWtlcyBubyBkaWZmZXJlbmNlIHdoZXRo ZXIgSSByZWdpc3RlciB0aGUgR1BJTyBhcmUKPiBhY3RpdmUgaGlnaCBvciBhY3RpdmUgbG93Li4u CgpUaGF0J3MgdW5mb3J0dW5hdGUuICBCdXQgbWF5YmUgdGhhdCdzIGFuIG9wcG9ydHVuaXR5IHRv IGZpeCB0aGUKZGV2aWNldHJlZSB0byB1c2UgR1BJT19BQ1RJVkVfTE9XIGZvciB0aGVzZSBHUElP cz8KCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4 LWFybS1rZXJuZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFk Lm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFy bS1rZXJuZWwK