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 64496C433F5 for ; Wed, 24 Nov 2021 09:03:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234255AbhKXJGO convert rfc822-to-8bit (ORCPT ); Wed, 24 Nov 2021 04:06:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:57638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233817AbhKXJGK (ORCPT ); Wed, 24 Nov 2021 04:06:10 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A545D60F50; Wed, 24 Nov 2021 09:03:00 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mpoB8-007TDe-Bh; Wed, 24 Nov 2021 09:02:58 +0000 Date: Wed, 24 Nov 2021 09:02:57 +0000 Message-ID: <87fsrmc4e6.wl-maz@kernel.org> From: Marc Zyngier To: Luca Ceresoli Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, Pali =?UTF-8?B?Um9ow6Fy?= , Alyssa Rosenzweig , Lorenzo Pieralisi , Bjorn Helgaas , Mark Kettenis , kernel-team@android.com Subject: Re: [PATCH v3 3/3] PCI: apple: Fix #PERST polarity In-Reply-To: <453389da-b041-94b3-009e-6c6323134936@lucaceresoli.net> References: <20211123180636.80558-1-maz@kernel.org> <20211123180636.80558-4-maz@kernel.org> <453389da-b041-94b3-009e-6c6323134936@lucaceresoli.net> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: luca@lucaceresoli.net, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, pali@kernel.org, alyssa@rosenzweig.io, lorenzo.pieralisi@arm.com, bhelgaas@google.com, mark.kettenis@xs4all.nl, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, 23 Nov 2021 21:36:11 +0000, Luca Ceresoli wrote: > > Hi Mark, > > On 23/11/21 19:06, Marc Zyngier wrote: > > Now that #PERST is properly defined as active-low in the device tree, > > fix the driver to correctly drive the line indemendently of the > > implied polarity. > > > > Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up") > > Suggested-by: Pali Rohár > > Signed-off-by: Marc Zyngier > > Thanks for quickly addressing this! > > Do we need a transition path for backward compatibility with old DTs > already around? Something like this [0]. You said [1] the DT actually > used is not even the one in the kernel, thus how do we guarantee DT and > driver switch to the new polarity all at once? No. As it turns out, neither u-boot nor OpenBSD (the only two other payloads that can boot on M1) are upstreamed yet. So we're still in that stage where we don't need to maintain backward compatibility. If we don't get this patches merged by the end of this cycle, we will have to revisit this though. > > [0] https://lkml.org/lkml/2021/6/24/1049 > [1] https://lkml.org/lkml/2021/11/23/455 > > > --- > > drivers/pci/controller/pcie-apple.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c > > index 957960a733c4..03bc56f39be5 100644 > > --- a/drivers/pci/controller/pcie-apple.c > > +++ b/drivers/pci/controller/pcie-apple.c > > @@ -540,7 +540,7 @@ 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); > > + gpiod_set_value(reset, 1); > > > > ret = apple_pcie_setup_refclk(pcie, port); > > if (ret < 0) > > @@ -551,7 +551,7 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie, > > > > /* Deassert #PERST */ > > rmw_set(PORT_PERST_OFF, port->base + PORT_PERST); > > - gpiod_set_value(reset, 1); > > + gpiod_set_value(reset, 0); > > Minor note: if it were me I would coalesce patches 1 and 3 together, > otherwise we are insisting on a wrong implementation (patch 1) to later > fix it all (this patch). The first patch is a clear bug fix that has a direct HW impact. The second patch is only sugar coating with zero material impact (absolutely nothing changes in the way the HW is driven). Squashing these two patches would be absolutely the wrong thing to do. M. -- Without deviation from the norm, progress is not possible. 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 EDD3EC433EF for ; Wed, 24 Nov 2021 09:04:32 +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:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=MMcP3Bsg360Zcmip7i9D8U8uJY3h6EQxzTyulEeLavE=; b=HvfYP+LOryqBZz Op7hIN0STKj4p4LxSi1WeqT+b1mBbUeqBEC0cCBAK9aoLmJVor6WTzAW/oaqblCjTE10ffFs+GpwB BIBUPhNDRCKOxbE86IiLbYf3460uCAsofgw3r6k9Ro0ys11HnvGk+ZR78q1g0HxK8ii0wv6Kig8tC qZ+A7Zd7QfsbL9n6gxids7Q2M6NU/U6VjAfQ+pHci92CkTcRESF01sCu/KIL3ViXD78LR4pskG30U fJzTCkz3Mx1fnl8BoGxkP1wcjNGlba1roM1JDzVjTF56S01mMHiAF6p7aijvZ7rY/ISJ0O6NYFQ6Y 3mu64XnjU/K8d3ZK7SgQ==; 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SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211124_010300_985903_7D4A1E34 X-CRM114-Status: GOOD ( 33.35 ) 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 T24gVHVlLCAyMyBOb3YgMjAyMSAyMTozNjoxMSArMDAwMCwKTHVjYSBDZXJlc29saSA8bHVjYUBs dWNhY2VyZXNvbGkubmV0PiB3cm90ZToKPiAKPiBIaSBNYXJrLAo+IAo+IE9uIDIzLzExLzIxIDE5 OjA2LCBNYXJjIFp5bmdpZXIgd3JvdGU6Cj4gPiBOb3cgdGhhdCAjUEVSU1QgaXMgcHJvcGVybHkg ZGVmaW5lZCBhcyBhY3RpdmUtbG93IGluIHRoZSBkZXZpY2UgdHJlZSwKPiA+IGZpeCB0aGUgZHJp dmVyIHRvIGNvcnJlY3RseSBkcml2ZSB0aGUgbGluZSBpbmRlbWVuZGVudGx5IG9mIHRoZQo+ID4g aW1wbGllZCBwb2xhcml0eS4KPiA+IAo+ID4gRml4ZXM6IDFlMzM4ODhmYmU0NCAoIlBDSTogYXBw bGU6IEFkZCBpbml0aWFsIGhhcmR3YXJlIGJyaW5nLXVwIikKPiA+IFN1Z2dlc3RlZC1ieTogUGFs aSBSb2jDoXIgPHBhbGlAa2VybmVsLm9yZz4KPiA+IFNpZ25lZC1vZmYtYnk6IE1hcmMgWnluZ2ll ciA8bWF6QGtlcm5lbC5vcmc+Cj4gCj4gVGhhbmtzIGZvciBxdWlja2x5IGFkZHJlc3NpbmcgdGhp cyEKPiAKPiBEbyB3ZSBuZWVkIGEgdHJhbnNpdGlvbiBwYXRoIGZvciBiYWNrd2FyZCBjb21wYXRp YmlsaXR5IHdpdGggb2xkIERUcwo+IGFscmVhZHkgYXJvdW5kPyBTb21ldGhpbmcgbGlrZSB0aGlz IFswXS4gWW91IHNhaWQgWzFdIHRoZSBEVCBhY3R1YWxseQo+IHVzZWQgaXMgbm90IGV2ZW4gdGhl IG9uZSBpbiB0aGUga2VybmVsLCB0aHVzIGhvdyBkbyB3ZSBndWFyYW50ZWUgRFQgYW5kCj4gZHJp dmVyIHN3aXRjaCB0byB0aGUgbmV3IHBvbGFyaXR5IGFsbCBhdCBvbmNlPwoKTm8uIEFzIGl0IHR1 cm5zIG91dCwgbmVpdGhlciB1LWJvb3Qgbm9yIE9wZW5CU0QgKHRoZSBvbmx5IHR3byBvdGhlcgpw YXlsb2FkcyB0aGF0IGNhbiBib290IG9uIE0xKSBhcmUgdXBzdHJlYW1lZCB5ZXQuIFNvIHdlJ3Jl IHN0aWxsIGluCnRoYXQgc3RhZ2Ugd2hlcmUgd2UgZG9uJ3QgbmVlZCB0byBtYWludGFpbiBiYWNr d2FyZCBjb21wYXRpYmlsaXR5LiBJZgp3ZSBkb24ndCBnZXQgdGhpcyBwYXRjaGVzIG1lcmdlZCBi eSB0aGUgZW5kIG9mIHRoaXMgY3ljbGUsIHdlIHdpbGwKaGF2ZSB0byByZXZpc2l0IHRoaXMgdGhv dWdoLgoKPiAKPiBbMF0gaHR0cHM6Ly9sa21sLm9yZy9sa21sLzIwMjEvNi8yNC8xMDQ5Cj4gWzFd IGh0dHBzOi8vbGttbC5vcmcvbGttbC8yMDIxLzExLzIzLzQ1NQo+IAo+ID4gLS0tCj4gPiAgZHJp dmVycy9wY2kvY29udHJvbGxlci9wY2llLWFwcGxlLmMgfCA0ICsrLS0KPiA+ICAxIGZpbGUgY2hh bmdlZCwgMiBpbnNlcnRpb25zKCspLCAyIGRlbGV0aW9ucygtKQo+ID4gCj4gPiBkaWZmIC0tZ2l0 IGEvZHJpdmVycy9wY2kvY29udHJvbGxlci9wY2llLWFwcGxlLmMgYi9kcml2ZXJzL3BjaS9jb250 cm9sbGVyL3BjaWUtYXBwbGUuYwo+ID4gaW5kZXggOTU3OTYwYTczM2M0Li4wM2JjNTZmMzliZTUg MTAwNjQ0Cj4gPiAtLS0gYS9kcml2ZXJzL3BjaS9jb250cm9sbGVyL3BjaWUtYXBwbGUuYwo+ID4g KysrIGIvZHJpdmVycy9wY2kvY29udHJvbGxlci9wY2llLWFwcGxlLmMKPiA+IEBAIC01NDAsNyAr NTQwLDcgQEAgc3RhdGljIGludCBhcHBsZV9wY2llX3NldHVwX3BvcnQoc3RydWN0IGFwcGxlX3Bj aWUgKnBjaWUsCj4gPiAgCXJtd19zZXQoUE9SVF9BUFBDTEtfRU4sIHBvcnQtPmJhc2UgKyBQT1JU X0FQUENMSyk7Cj4gPiAgCj4gPiAgCS8qIEVuZ2FnZSAjUEVSU1QgYmVmb3JlIHNldHRpbmcgdXAg dGhlIGNsb2NrICovCj4gPgo+ID4gLQlncGlvZF9zZXRfdmFsdWUocmVzZXQsIDApOwo+ID4gKwln cGlvZF9zZXRfdmFsdWUocmVzZXQsIDEpOwo+ID4gIAo+ID4gIAlyZXQgPSBhcHBsZV9wY2llX3Nl dHVwX3JlZmNsayhwY2llLCBwb3J0KTsKPiA+ICAJaWYgKHJldCA8IDApCj4gPiBAQCAtNTUxLDcg KzU1MSw3IEBAIHN0YXRpYyBpbnQgYXBwbGVfcGNpZV9zZXR1cF9wb3J0KHN0cnVjdCBhcHBsZV9w Y2llICpwY2llLAo+ID4gIAo+ID4gIAkvKiBEZWFzc2VydCAjUEVSU1QgKi8KPiA+ICAJcm13X3Nl dChQT1JUX1BFUlNUX09GRiwgcG9ydC0+YmFzZSArIFBPUlRfUEVSU1QpOwo+ID4gLQlncGlvZF9z ZXRfdmFsdWUocmVzZXQsIDEpOwo+ID4gKwlncGlvZF9zZXRfdmFsdWUocmVzZXQsIDApOwo+IAo+ IE1pbm9yIG5vdGU6IGlmIGl0IHdlcmUgbWUgSSB3b3VsZCBjb2FsZXNjZSBwYXRjaGVzIDEgYW5k IDMgdG9nZXRoZXIsCj4gb3RoZXJ3aXNlIHdlIGFyZSBpbnNpc3Rpbmcgb24gYSB3cm9uZyBpbXBs ZW1lbnRhdGlvbiAocGF0Y2ggMSkgdG8gbGF0ZXIKPiBmaXggaXQgYWxsICh0aGlzIHBhdGNoKS4K ClRoZSBmaXJzdCBwYXRjaCBpcyBhIGNsZWFyIGJ1ZyBmaXggdGhhdCBoYXMgYSBkaXJlY3QgSFcg aW1wYWN0LiBUaGUKc2Vjb25kIHBhdGNoIGlzIG9ubHkgc3VnYXIgY29hdGluZyB3aXRoIHplcm8g bWF0ZXJpYWwgaW1wYWN0CihhYnNvbHV0ZWx5IG5vdGhpbmcgY2hhbmdlcyBpbiB0aGUgd2F5IHRo ZSBIVyBpcyBkcml2ZW4pLiBTcXVhc2hpbmcKdGhlc2UgdHdvIHBhdGNoZXMgd291bGQgYmUgYWJz b2x1dGVseSB0aGUgd3JvbmcgdGhpbmcgdG8gZG8uCgoJTS4KCi0tIApXaXRob3V0IGRldmlhdGlv biBmcm9tIHRoZSBub3JtLCBwcm9ncmVzcyBpcyBub3QgcG9zc2libGUuCgpfX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxp bmcgbGlzdApsaW51eC1hcm0ta2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3Rz LmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1hcm0ta2VybmVsCg==