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 X-Spam-Level: X-Spam-Status: No, score=-7.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C483C49EA2 for ; Tue, 22 Jun 2021 12:17:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 45BF060C41 for ; Tue, 22 Jun 2021 12:17:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231437AbhFVMTQ (ORCPT ); Tue, 22 Jun 2021 08:19:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:38322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231464AbhFVMTJ (ORCPT ); Tue, 22 Jun 2021 08:19:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 27BD2611CE; Tue, 22 Jun 2021 12:16:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624364213; bh=+DSoQii3QA6TNarjz5jdOxe8E+65XqNOB0H4z1VVg/c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KUosdjs1ssfAL/o0RkE2+ODxWK+fo636fpSl89g0ENmRCX5LIIq+VfQwpAwn09spb Njb6ysVBXcl8LyNzd8UDYlf+VP2qbSkBGh0rzi4n4DWYfKwXK0B+SUMvf8UCkBhN41 M9ZznVnwo9BAxhNkMNnHxO564RJBnhCeopkCJkQ6JQ1E9p9UwrMzvC4VBVIyz4Widr ZqL5mJpAaGsj8YPUWtCyvA0MMbC6O++jVt0n2s8mQQdjG35+UGym/N9imsiyW2i8Y0 gmGQprIsJ3ecWqdcekUnet809cl1EWH88cqqUks0ln1t6VWrxSrez+uQGFMZO/RzZu e0qYDySCGZWzw== Received: by pali.im (Postfix) id D9595889; Tue, 22 Jun 2021 14:16:49 +0200 (CEST) Date: Tue, 22 Jun 2021 14:16:49 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Lorenzo Pieralisi Cc: linus.walleij@linaro.org, kishon@ti.com, Luca Ceresoli , linux-pci@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Rob Herring , Bjorn Helgaas Subject: Re: [PATCH v2] PCI: dra7xx: Fix reset behaviour Message-ID: <20210622121649.ouiaecdvwutgdyy5@pali> References: <20210531090540.2663171-1-luca@lucaceresoli.net> <20210531133211.llyiq3jcfy25tmz4@pali> <8ff1c54f-bb29-1e40-8342-905e34361e1c@lucaceresoli.net> <9fdbada4-4902-cec1-f283-0d12e1d4ac64@ti.com> <20210531162242.jm73yzntzmilsvbg@pali> <8207a53c-4de9-d0e5-295a-c165e7237e36@lucaceresoli.net> <20210622110627.aqzxxtf2j3uxfeyl@pali> <20210622115604.GA25503@lpieralisi> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210622115604.GA25503@lpieralisi> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 22 June 2021 12:56:04 Lorenzo Pieralisi wrote: > [Adding Linus for GPIO discussion, thread: > https://lore.kernel.org/linux-pci/20210531090540.2663171-1-luca@lucaceresoli.net] > > On Tue, Jun 22, 2021 at 01:06:27PM +0200, Pali Rohár wrote: > > Hello! > > > > On Tuesday 22 June 2021 12:57:22 Luca Ceresoli wrote: > > > Nothing happened after a few weeks... I understand that knowing the > > > correct reset timings is relevant, but unfortunately I cannot help much > > > in finding out the correct values. > > > > > > However I'm wondering what should happen to this patch. It *does* fix a > > > real bug, but potentially with an incorrect or non-optimal usleep range. > > > Do we really want to ignore a bugfix because we are not sure about how > > > long this delay should be? > > > > As there is no better solution right now, I'm fine with your patch. But > > patch needs to be approved by Lorenzo, so please wait for his final > > answer. > > I am not a GPIO expert and I have a feeling this is platform specific > beyond what the PCI specification can actually define architecturally. In my opinion timeout is not platform specific as I wrote in email: https://lore.kernel.org/linux-pci/20210310110535.zh4pnn4vpmvzwl5q@pali/ My experiments already proved that some PCIe cards needs to be in reset state for some minimal time otherwise they cannot be enumerated. And it does not matter to which platform you connect those (endpoint) cards. I do not think that timeout itself is platform specific. GPIO controls PERST# pin and therefore specified sleep value directly drives how long is card on the other end of PCIe slot in Warm Reset state. PCIe CEM spec directly says that PERST# signal controls PCIe Warm Reset. What is here platform specific thing is that PERST# signal is controlled by GPIO. But value of signal (high / low) and how long is in signal in which state for me sounds like not an platform specific thing, but as PCIe / CEM related. > There are two things I'd like to see: > > 1) If Linus can have a look at the GPIO bits in this thread that would > definitely help clarify any pending controversy > 2) Kishon to test on *existing* platforms and confirm there are no > regressions triggered > > > I would suggest to add a comment for call "usleep_range(1000, 2000);" > > that you have chosen some "random" values which worked fine on your > > setup and that they fix mentioned bug. Comment just to mark this sleep > > code that is suboptimal / not-so-correct and to prevent other people to > > copy+paste this code into other (new) drivers... > > Yes a comment would help but as I say above I am afraid this is > a platform specific set-up, ie that delay is somewhat tied to > a platform, not sure there is anything we can do. > > If Linus and Kishon are happy with the approach we can merge this > patch. > > Lorenzo 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 X-Spam-Level: X-Spam-Status: No, score=-5.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE2D3C2B9F4 for ; Tue, 22 Jun 2021 12:18:52 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 87E4161353 for ; 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Tue, 22 Jun 2021 14:16:49 +0200 (CEST) Date: Tue, 22 Jun 2021 14:16:49 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Lorenzo Pieralisi Cc: linus.walleij@linaro.org, kishon@ti.com, Luca Ceresoli , linux-pci@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Rob Herring , Bjorn Helgaas Subject: Re: [PATCH v2] PCI: dra7xx: Fix reset behaviour Message-ID: <20210622121649.ouiaecdvwutgdyy5@pali> References: <20210531090540.2663171-1-luca@lucaceresoli.net> <20210531133211.llyiq3jcfy25tmz4@pali> <8ff1c54f-bb29-1e40-8342-905e34361e1c@lucaceresoli.net> <9fdbada4-4902-cec1-f283-0d12e1d4ac64@ti.com> <20210531162242.jm73yzntzmilsvbg@pali> <8207a53c-4de9-d0e5-295a-c165e7237e36@lucaceresoli.net> <20210622110627.aqzxxtf2j3uxfeyl@pali> <20210622115604.GA25503@lpieralisi> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210622115604.GA25503@lpieralisi> User-Agent: NeoMutt/20180716 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210622_051653_918160_0226E779 X-CRM114-Status: GOOD ( 30.60 ) 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 T24gVHVlc2RheSAyMiBKdW5lIDIwMjEgMTI6NTY6MDQgTG9yZW56byBQaWVyYWxpc2kgd3JvdGU6 Cj4gW0FkZGluZyBMaW51cyBmb3IgR1BJTyBkaXNjdXNzaW9uLCB0aHJlYWQ6Cj4gaHR0cHM6Ly9s b3JlLmtlcm5lbC5vcmcvbGludXgtcGNpLzIwMjEwNTMxMDkwNTQwLjI2NjMxNzEtMS1sdWNhQGx1 Y2FjZXJlc29saS5uZXRdCj4gCj4gT24gVHVlLCBKdW4gMjIsIDIwMjEgYXQgMDE6MDY6MjdQTSAr MDIwMCwgUGFsaSBSb2jDoXIgd3JvdGU6Cj4gPiBIZWxsbyEKPiA+IAo+ID4gT24gVHVlc2RheSAy MiBKdW5lIDIwMjEgMTI6NTc6MjIgTHVjYSBDZXJlc29saSB3cm90ZToKPiA+ID4gTm90aGluZyBo YXBwZW5lZCBhZnRlciBhIGZldyB3ZWVrcy4uLiBJIHVuZGVyc3RhbmQgdGhhdCBrbm93aW5nIHRo ZQo+ID4gPiBjb3JyZWN0IHJlc2V0IHRpbWluZ3MgaXMgcmVsZXZhbnQsIGJ1dCB1bmZvcnR1bmF0 ZWx5IEkgY2Fubm90IGhlbHAgbXVjaAo+ID4gPiBpbiBmaW5kaW5nIG91dCB0aGUgY29ycmVjdCB2 YWx1ZXMuCj4gPiA+IAo+ID4gPiBIb3dldmVyIEknbSB3b25kZXJpbmcgd2hhdCBzaG91bGQgaGFw cGVuIHRvIHRoaXMgcGF0Y2guIEl0ICpkb2VzKiBmaXggYQo+ID4gPiByZWFsIGJ1ZywgYnV0IHBv dGVudGlhbGx5IHdpdGggYW4gaW5jb3JyZWN0IG9yIG5vbi1vcHRpbWFsIHVzbGVlcCByYW5nZS4K PiA+ID4gRG8gd2UgcmVhbGx5IHdhbnQgdG8gaWdub3JlIGEgYnVnZml4IGJlY2F1c2Ugd2UgYXJl IG5vdCBzdXJlIGFib3V0IGhvdwo+ID4gPiBsb25nIHRoaXMgZGVsYXkgc2hvdWxkIGJlPwo+ID4g Cj4gPiBBcyB0aGVyZSBpcyBubyBiZXR0ZXIgc29sdXRpb24gcmlnaHQgbm93LCBJJ20gZmluZSB3 aXRoIHlvdXIgcGF0Y2guIEJ1dAo+ID4gcGF0Y2ggbmVlZHMgdG8gYmUgYXBwcm92ZWQgYnkgTG9y ZW56bywgc28gcGxlYXNlIHdhaXQgZm9yIGhpcyBmaW5hbAo+ID4gYW5zd2VyLgo+IAo+IEkgYW0g bm90IGEgR1BJTyBleHBlcnQgYW5kIEkgaGF2ZSBhIGZlZWxpbmcgdGhpcyBpcyBwbGF0Zm9ybSBz cGVjaWZpYwo+IGJleW9uZCB3aGF0IHRoZSBQQ0kgc3BlY2lmaWNhdGlvbiBjYW4gYWN0dWFsbHkg ZGVmaW5lIGFyY2hpdGVjdHVyYWxseS4KCkluIG15IG9waW5pb24gdGltZW91dCBpcyBub3QgcGxh dGZvcm0gc3BlY2lmaWMgYXMgSSB3cm90ZSBpbiBlbWFpbDoKaHR0cHM6Ly9sb3JlLmtlcm5lbC5v cmcvbGludXgtcGNpLzIwMjEwMzEwMTEwNTM1LnpoNHBubjR2cG12endsNXFAcGFsaS8KCk15IGV4 cGVyaW1lbnRzIGFscmVhZHkgcHJvdmVkIHRoYXQgc29tZSBQQ0llIGNhcmRzIG5lZWRzIHRvIGJl IGluIHJlc2V0CnN0YXRlIGZvciBzb21lIG1pbmltYWwgdGltZSBvdGhlcndpc2UgdGhleSBjYW5u b3QgYmUgZW51bWVyYXRlZC4gQW5kIGl0CmRvZXMgbm90IG1hdHRlciB0byB3aGljaCBwbGF0Zm9y bSB5b3UgY29ubmVjdCB0aG9zZSAoZW5kcG9pbnQpIGNhcmRzLgoKSSBkbyBub3QgdGhpbmsgdGhh dCB0aW1lb3V0IGl0c2VsZiBpcyBwbGF0Zm9ybSBzcGVjaWZpYy4gR1BJTyBjb250cm9scwpQRVJT VCMgcGluIGFuZCB0aGVyZWZvcmUgc3BlY2lmaWVkIHNsZWVwIHZhbHVlIGRpcmVjdGx5IGRyaXZl cyBob3cgbG9uZwppcyBjYXJkIG9uIHRoZSBvdGhlciBlbmQgb2YgUENJZSBzbG90IGluIFdhcm0g UmVzZXQgc3RhdGUuIFBDSWUgQ0VNIHNwZWMKZGlyZWN0bHkgc2F5cyB0aGF0IFBFUlNUIyBzaWdu YWwgY29udHJvbHMgUENJZSBXYXJtIFJlc2V0LgoKV2hhdCBpcyBoZXJlIHBsYXRmb3JtIHNwZWNp ZmljIHRoaW5nIGlzIHRoYXQgUEVSU1QjIHNpZ25hbCBpcyBjb250cm9sbGVkCmJ5IEdQSU8uIEJ1 dCB2YWx1ZSBvZiBzaWduYWwgKGhpZ2ggLyBsb3cpIGFuZCBob3cgbG9uZyBpcyBpbiBzaWduYWwg aW4Kd2hpY2ggc3RhdGUgZm9yIG1lIHNvdW5kcyBsaWtlIG5vdCBhbiBwbGF0Zm9ybSBzcGVjaWZp YyB0aGluZywgYnV0IGFzClBDSWUgLyBDRU0gcmVsYXRlZC4KCj4gVGhlcmUgYXJlIHR3byB0aGlu Z3MgSSdkIGxpa2UgdG8gc2VlOgo+IAo+IDEpIElmIExpbnVzIGNhbiBoYXZlIGEgbG9vayBhdCB0 aGUgR1BJTyBiaXRzIGluIHRoaXMgdGhyZWFkIHRoYXQgd291bGQKPiAgICBkZWZpbml0ZWx5IGhl bHAgY2xhcmlmeSBhbnkgcGVuZGluZyBjb250cm92ZXJzeQo+IDIpIEtpc2hvbiB0byB0ZXN0IG9u ICpleGlzdGluZyogcGxhdGZvcm1zIGFuZCBjb25maXJtIHRoZXJlIGFyZSBubwo+ICAgIHJlZ3Jl c3Npb25zIHRyaWdnZXJlZAo+IAo+ID4gSSB3b3VsZCBzdWdnZXN0IHRvIGFkZCBhIGNvbW1lbnQg Zm9yIGNhbGwgInVzbGVlcF9yYW5nZSgxMDAwLCAyMDAwKTsiCj4gPiB0aGF0IHlvdSBoYXZlIGNo b3NlbiBzb21lICJyYW5kb20iIHZhbHVlcyB3aGljaCB3b3JrZWQgZmluZSBvbiB5b3VyCj4gPiBz ZXR1cCBhbmQgdGhhdCB0aGV5IGZpeCBtZW50aW9uZWQgYnVnLiBDb21tZW50IGp1c3QgdG8gbWFy ayB0aGlzIHNsZWVwCj4gPiBjb2RlIHRoYXQgaXMgc3Vib3B0aW1hbCAvIG5vdC1zby1jb3JyZWN0 IGFuZCB0byBwcmV2ZW50IG90aGVyIHBlb3BsZSB0bwo+ID4gY29weStwYXN0ZSB0aGlzIGNvZGUg aW50byBvdGhlciAobmV3KSBkcml2ZXJzLi4uCj4gCj4gWWVzIGEgY29tbWVudCB3b3VsZCBoZWxw IGJ1dCBhcyBJIHNheSBhYm92ZSBJIGFtIGFmcmFpZCB0aGlzIGlzCj4gYSBwbGF0Zm9ybSBzcGVj aWZpYyBzZXQtdXAsIGllIHRoYXQgZGVsYXkgaXMgc29tZXdoYXQgdGllZCB0bwo+IGEgcGxhdGZv cm0sIG5vdCBzdXJlIHRoZXJlIGlzIGFueXRoaW5nIHdlIGNhbiBkby4KPiAKPiBJZiBMaW51cyBh bmQgS2lzaG9uIGFyZSBoYXBweSB3aXRoIHRoZSBhcHByb2FjaCB3ZSBjYW4gbWVyZ2UgdGhpcwo+ IHBhdGNoLgo+IAo+IExvcmVuem8KCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFybS1rZXJu ZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFu L2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK