From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bl2on0114.outbound.protection.outlook.com ([65.55.169.114]:37020 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756408AbaIILP3 (ORCPT ); Tue, 9 Sep 2014 07:15:29 -0400 Message-ID: <540F51F1.1060909@freescale.com> Date: Tue, 9 Sep 2014 19:16:01 +0000 From: Lian Minghuan-B31939 MIME-Version: 1.0 To: Arnd Bergmann CC: "Minghuan.Lian@freescale.com" , "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , "Mingkai.Hu@freescale.com" , Roy Zang Subject: Re: =?UTF-8?B?562U5aSNOiBbUEFUQ0ggMi8yXSBQQ0k6IExheWVyc2NhcGU6IEE=?= =?UTF-8?B?ZGQgTGF5ZXJzY2FwZSBQQ0llIGRyaXZlcg==?= References: <1409856338-1730-1-git-send-email-Minghuan.Lian@freescale.com> <6844751.zBSvS2zU47@wuerfel> <540F4B23.5040209@freescale.com> <60096763.M59cqLJ4gm@wuerfel> In-Reply-To: <60096763.M59cqLJ4gm@wuerfel> Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: On 2014年09月09日 10:50, Arnd Bergmann wrote: > On Tuesday 09 September 2014 18:46:59 Lian Minghuan-B31939 wrote: >> On 2014年09月09日 09:56, Arnd Bergmann wrote: >>> On Tuesday 09 September 2014 17:25:57 Lian Minghuan-B31939 wrote: >>>> [Minghuan] I discussed with my colleague. They worry about performance >>>> degradation if using regmap API, >>>> because there are some fast device use scfg. We tend to use a simple way >>>> to map andread/write scfg directly. >>> I see. In this case, I would probably create a separate msi controller >>> driver that owns the "fsl,ls1021a-scfg" device, and is referenced >>> through the "msi-parent" property in the pcie controller. >>> >>> You can use of_pci_find_msi_chip_by_node() to get the msi_chip >>> instance and then connect that to your pci host. This will also >>> take care of the case where you may want to use the main GICv3 >>> on a future SoC. >> [Minghuan] There is something wrong with LS1021A MSI hardware that it >> only supports one interrupt not 32 interrupts. Now, I do not want to >> create a separate msi controller driver just for incorrect hardware. >> I may provide complete MSI driver for the new hardware when it is ready. > Would you just leave out MSI support for the LS1021A PCIe variant? > I guess that's fine because all device drivers should also support > legacy interrupts and there is no performance gain in MSI in this > case. [Minghuan] I have added MSI support for LS1021A PCIe just reserved 31 interrupts as used. > Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: B31939@freescale.com (Lian Minghuan-B31939) Date: Tue, 9 Sep 2014 19:16:01 +0000 Subject: =?UTF-8?B?562U5aSNOiBbUEFUQ0ggMi8yXSBQQ0k6IExheWVyc2NhcGU6IEE=?= =?UTF-8?B?ZGQgTGF5ZXJzY2FwZSBQQ0llIGRyaXZlcg==?= In-Reply-To: <60096763.M59cqLJ4gm@wuerfel> References: <1409856338-1730-1-git-send-email-Minghuan.Lian@freescale.com> <6844751.zBSvS2zU47@wuerfel> <540F4B23.5040209@freescale.com> <60096763.M59cqLJ4gm@wuerfel> Message-ID: <540F51F1.1060909@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2014?09?09? 10:50, Arnd Bergmann wrote: > On Tuesday 09 September 2014 18:46:59 Lian Minghuan-B31939 wrote: >> On 2014?09?09? 09:56, Arnd Bergmann wrote: >>> On Tuesday 09 September 2014 17:25:57 Lian Minghuan-B31939 wrote: >>>> [Minghuan] I discussed with my colleague. They worry about performance >>>> degradation if using regmap API, >>>> because there are some fast device use scfg. We tend to use a simple way >>>> to map andread/write scfg directly. >>> I see. In this case, I would probably create a separate msi controller >>> driver that owns the "fsl,ls1021a-scfg" device, and is referenced >>> through the "msi-parent" property in the pcie controller. >>> >>> You can use of_pci_find_msi_chip_by_node() to get the msi_chip >>> instance and then connect that to your pci host. This will also >>> take care of the case where you may want to use the main GICv3 >>> on a future SoC. >> [Minghuan] There is something wrong with LS1021A MSI hardware that it >> only supports one interrupt not 32 interrupts. Now, I do not want to >> create a separate msi controller driver just for incorrect hardware. >> I may provide complete MSI driver for the new hardware when it is ready. > Would you just leave out MSI support for the LS1021A PCIe variant? > I guess that's fine because all device drivers should also support > legacy interrupts and there is no performance gain in MSI in this > case. [Minghuan] I have added MSI support for LS1021A PCIe just reserved 31 interrupts as used. > Arnd