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 759E7C77B7C for ; Tue, 9 May 2023 07:51:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229610AbjEIHvU (ORCPT ); Tue, 9 May 2023 03:51:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229533AbjEIHvT (ORCPT ); Tue, 9 May 2023 03:51:19 -0400 Received: from stravinsky.debian.org (stravinsky.debian.org [IPv6:2001:41b8:202:deb::311:108]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 859C310A; Tue, 9 May 2023 00:51:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=SHJ8rFSlgUKip49JflDFe5hQHWXdms45Qv37jV17d5w=; b=LYJOKkK6psZo49sTPJGzmdoj7k 5VuwqsJLQyo80OVasAwU0HX77BHFvCBgRQg5VlaGeG16uQMkJH0sxUjnpGndUa2NrUlpcdu0MmGwR 8a+2hCdugNMm4+7LbgABnPvnClCTEKabCqh1vrFC1m8haVpwaG0MlVkA0Wd58mpmgPiff/Z9jFOXJ zh0tV+dMSY4R/lh2aW87IqCycGgmqCSD/1RxryqqtT5I2emqQ0XBWL6YF84Od8oVwNmWDuXGaV5zc dKB7cM5T4euJqhlvTn3FEks/0vaE2zsaLlSv/Vpuii9iCSvEZr646+3rEhiPez4ppW3wlE0T/WUBu /xTybutQ==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1pwI7v-008YdF-Qy; Tue, 09 May 2023 07:51:16 +0000 Date: Tue, 9 May 2023 09:51:13 +0200 From: Cyril Brulebois To: Jim Quinlan Cc: linux-pci@vger.kernel.org, Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , Phil Elwell , bcm-kernel-feedback-list@broadcom.com, james.quinlan@broadcom.com, Florian Fainelli , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , open list Subject: Re: [PATCH v5 4/5] PCI: brcmstb: Don't assume 2711 bootloader leaves PERST# asserted Message-ID: <20230509075113.5cosbeaoykdoiefa@mraw.org> Organization: Debian References: <20230508220126.16241-1-jim2101024@gmail.com> <20230508220126.16241-5-jim2101024@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="udbgdswpzmjgu2ia" Content-Disposition: inline In-Reply-To: <20230508220126.16241-5-jim2101024@gmail.com> X-Debian-User: kibi Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org --udbgdswpzmjgu2ia Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, Jim Quinlan (2023-05-08): > The current PCIe driver assumes PERST# is asserted when probe() is invoke= d. > The reasons are as follows: >=20 > (1) One Broadcom SOC (7278) causes a panic if the PERST# register is > written during this time window. >=20 > (2) If PERST# is deasserted at Linux probe() time, experience and QA > suspend/resume tests have shown that some endpoint devices fail if the > PERST# is pulsed (deasserted =3D> asserted =3D> deasserted) quickly i= n this > fashion, even though the timing is in accordance with their datasheet= s. >=20 > (3) Keeping things in reset tends to save power, if for some reason the > PCIe driver is not yet present. >=20 > Broadcom STB and CM SOCs bootloaders always have PERST# asserted at > probe(). This is not necessarily the case for the 2711/RPi bootloader, > so, for 2711/RPi SOCs, do what Raspian OS does and assert PERST#. >=20 > [1] https://lore.kernel.org/linux-pci/20230411165919.23955-1-jim2101024@g= mail.com/T/#m39ebab8bc2827b2304aeeff470a6c6a58f46f987 It would probably make sense to remove that [1] link entirely, to match the reference removal between v4 and v5. Cheers, --=20 Cyril Brulebois (kibi@debian.org) D-I release manager -- Release team member -- Freelance Consultant --udbgdswpzmjgu2ia Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEtg6/KYRFPHDXTPR4/5FK8MKzVSAFAmRZ+3EACgkQ/5FK8MKz VSDPThAAnjd8pxRB2dH/ulH/Kg5l7D03KJPKpRRNXw9EvnVD25SsERIcoGvzS6+E b6UhVz/DznrrMZIa3m4URUkYZjAKOs4epXEpIHMLY6hHtdlSq4fVNN4MGjVGF8Gv P4ZRrh8MgX8dbGsWpew146ftkUAlDxF2tJH+m5/URm6ME6equZYmyY/hcak2GE7X i74oEb8UkC3QfTXKL4APwfSirU8XoyjTjdmfkB8PENVMfh61Z0SM4x+f9vSVYEwX AqkCHruEO4IfmP7A1d1vsjP0dGdYDojknZnNBBeBGfUGisFMN0QFqBoUfcXOJuuF b6UjJT2RNgFyVmqRKvP4nVEFpIj23eah/2uBDfgLbS/6dqbwKTuxgZonHkASJkLK gh67DnvMOht93JV0hT43XObjm6v+2yh4TXXNnVniywMhSGNEuJjrr4fYxS1Puq80 DzoxRvgAfpe2xRUBom0/SxJGBJKOZFzZmSQh5B2yaeizei7p2mdaWXCfKEtMDbI1 Z8K2rK5iXEidcDbu4Xw8znhWjg8/ukKH7dlAlkzYGY/aM8unpIEasHPJFos0oU1A JyRrDsmHgMfhU8VllwcaU7g/Nef4WcFAwoBxWBm1lWW7YlpP9k0emwcRtMYm9fZz Tbt/RWlpSLNku1m4GauKpOOS7cstZF5/727QA0ep4re31xQEdPI= =y2a+ -----END PGP SIGNATURE----- --udbgdswpzmjgu2ia--