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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 C78B8C43215 for ; Tue, 3 Dec 2019 17:23:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A595A206E4 for ; Tue, 3 Dec 2019 17:23:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727177AbfLCRXI (ORCPT ); Tue, 3 Dec 2019 12:23:08 -0500 Received: from mx2.suse.de ([195.135.220.15]:51018 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726422AbfLCRXI (ORCPT ); Tue, 3 Dec 2019 12:23:08 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 83641B2074; Tue, 3 Dec 2019 17:23:05 +0000 (UTC) Message-ID: Subject: Re: [PATCH v3 4/7] PCI: brcmstb: add Broadcom STB PCIe host controller driver From: Nicolas Saenz Julienne To: Jeremy Linton , andrew.murray@arm.com, maz@kernel.org, linux-kernel@vger.kernel.org, Lorenzo Pieralisi , Eric Anholt , Stefan Wahren , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com Cc: james.quinlan@broadcom.com, mbrugger@suse.com, phil@raspberrypi.org, linux-pci@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, Bjorn Helgaas , linux-arm-kernel@lists.infradead.org Date: Tue, 03 Dec 2019 18:23:03 +0100 In-Reply-To: References: <20191126091946.7970-1-nsaenzjulienne@suse.de> <20191126091946.7970-5-nsaenzjulienne@suse.de> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-tiQfYVDELUAGwVd1u8VU" User-Agent: Evolution 3.34.1 MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-tiQfYVDELUAGwVd1u8VU Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2019-12-03 at 10:31 -0600, Jeremy Linton wrote: > Hi, >=20 > On 11/26/19 3:19 AM, Nicolas Saenz Julienne wrote: > > From: Jim Quinlan > >=20 > > This adds a basic driver for Broadcom's STB PCIe controller, for now > > aimed at Raspberry Pi 4's SoC, bcm2711. > >=20 > > Signed-off-by: Jim Quinlan > > Co-developed-by: Nicolas Saenz Julienne > > Signed-off-by: Nicolas Saenz Julienne > >=20 > > --- > >=20 > > Changes since v2: > > - Correct rc_bar2_offset sign > > - Invert IRQ clear and masking in setup code > > - Use bitfield.h, redo all register ops while keeping the register > > names intact > > - Remove all SHIFT register definitions > > - Get rid of all _RB writes > > - Get rid of of_data > > - Don't iterate over inexisting dma-ranges > > - Add comment regarding dma-ranges validation > > - Small cosmetic cleanups > > - Fix license mismatch > > - Set driver Kconfig tristate > > - Didn't add any comment about the controller not being I/O coherent > > for now as I wait for Jeremy's reply >=20 > I guess its fine.. In answer to the original query. It seems that this= =20 > PCIe bridge requires explicit cache operations for DMA from PCIe=20 > endpoints. This wasn't obvious to me at first reading because I was=20 > assuming the custom DMA ops were strictly to deal with the stated DMA=20 > limits. Thanks, I now see what you meant. > So if you end up respinning, it still might be worthy mentioning=20 > somewhere that this is a non-coherent PCIe implementation. I still hold= =20 > much of my original reservations about pieces of this driver.=20 > Particularly, how it might look if someone wanted to boot the RPi using= =20 > ACPI on linux. But, I was shown a clever bit of AML recently, which=20 > solves those problems for the RPi and the attached XHCI. I don't know much about ACPI, but ultimately if you're booting trough ACPI, you're unlikely to use device-tree at all, right? And if you where and this driver clashed with your ACPI implementation you'd simply have to disable i= t on the device-tree. > So, given how much time I've looked at the root port configuration/etc= =20 > sections of this driver and I've not found a serious bug: >=20 > Reviewed-by: Jeremy Linton Thanks! Regards, Nicolas --=-tiQfYVDELUAGwVd1u8VU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAl3mmfcACgkQlfZmHno8 x/526wf/dHShet63is8+wboQUSa9Ik3p1r5FrbuSercRQWbob00Roa1615tbyVSg vJvel1G4DtTT/bDzL7xsp4eixx0NeInNcuJvv9bBveOzD5U1TAFdlHu4o2wVtFVF oqQevC+iJoMb4NX9qECr8NHoRgyBaw9fakVjgMRZ/xhqHQ1edsqJVjHcUHBVv6D8 w4r5CbB3AYmidDDOCx62CO6xKq+zHWg6yAVbDbCnisIc/zWA/F+Lq7U0ukqEP1aF vthC/OvlaQXB7c9ui7cXtklRXL00yGBgpShG5TOQrNP1WInlUG5IkheQm3kdKYob 4k2yRLGOlwt8fOiPz3s2RCWt6NtXRg== =ByNX -----END PGP SIGNATURE----- --=-tiQfYVDELUAGwVd1u8VU--