Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936869AbdCJNAK (ORCPT ); Fri, 10 Mar 2017 08:00:10 -0500 Received: from fllnx209.ext.ti.com ([198.47.19.16]:46811 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934057AbdCJNAG (ORCPT ); Fri, 10 Mar 2017 08:00:06 -0500 Subject: Re: [RESEND PATCH v3 4/7] PCI: dwc: all: Modify dbi accessors to take dbi_base as argument To: Niklas Cassel , Bjorn Helgaas , Joao Pinto , , , , References: <1489041545-15730-1-git-send-email-kishon@ti.com> <1489041545-15730-5-git-send-email-kishon@ti.com> <4e13580d-2625-5eed-bcbc-2ffd7493b073@axis.com> <595fab62-fb7a-888a-f898-7b59030585f1@axis.com> <58C28FCC.4070100@ti.com> CC: , Jingoo Han , Richard Zhu , Lucas Stach , Murali Karicheri , Thomas Petazzoni , Jesper Nilsson , Zhou Wang , Gabriele Paoloni From: Kishon Vijay Abraham I Message-ID: <58C2A28C.60703@ti.com> Date: Fri, 10 Mar 2017 18:26:44 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2133 Lines: 54 Hi Niklas, On Friday 10 March 2017 06:01 PM, Niklas Cassel wrote: > On 03/10/2017 12:36 PM, Kishon Vijay Abraham I wrote: >> Hi, >> >> On Thursday 09 March 2017 08:35 PM, Niklas Cassel wrote: >>> >>> On 03/09/2017 03:48 PM, Niklas Cassel wrote: >>>> On 03/09/2017 07:39 AM, Kishon Vijay Abraham I wrote: >>>>> dwc has 2 dbi address space labeled dbics and dbics2. The existing >>>>> helper to access dbi address space can access only dbics. However >>>>> dbics2 has to be accessed for programming the BAR registers in the >>>>> case of EP mode. This is in preparation for adding EP mode support >>>>> to dwc driver. >>>> Hello Kishon >>>> >>>> I don't really like the idea of adding an extra argument to every existing read/write. >>>> Will not a read/write using dbi2 be quite uncommon compared to a read/write >>>> using dbi? >>>> >>>> How about something like this: >>>> >>>> void __dw_pcie_writel(struct dw_pcie *pci, void __iomem *base, u32 reg, u32 val) >>>> { >>>> if (pci->ops->writel_dbi) >>>> pci->ops->writel_dbi(pci, base, reg, val); >>>> else >>>> writel(val, base + reg); >>>> } >>>> >>>> #define dw_pcie_writel_dbi(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base, reg, val) >>>> #define dw_pcie_writel_dbi2(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base2, reg, val) >>> Perhaps make dw_pcie_writel_dbi2 a function rather than a define, >>> so we can return an error if pci->dbi_base2 == NULL. >> Should we return an error? We don't return error for dbi_base either. I think >> it should be sufficient to return errors while populating dbi_base or >> dbi_base2. Otherwise it's a bug and should result in abort. Joao? > > Sorry for previous empty email. > > > What I meant to write: > > Right now we do error checking for dbi_base in platform specific code > and in pcie-designware-host.c:dw_pcie_host_init. it's been done in dw_pcie_host_init not as an error checking but since it's *optional* for certain platforms to populate dbi_base (i.e where dbi_base is mapped to configuration space), host_init takes care of assigning dbi_base to configuration space address. Thanks Kishon