Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753351AbdLUQnu (ORCPT ); Thu, 21 Dec 2017 11:43:50 -0500 Received: from mail-qk0-f193.google.com ([209.85.220.193]:42843 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751655AbdLUQnq (ORCPT ); Thu, 21 Dec 2017 11:43:46 -0500 X-Google-Smtp-Source: ACJfBovo5eWpRpPkGaRiP1LeGC/Tq060bL+ELFxnGp4hTSeqABujUFP+v23rFApexQadpLQnY36jIg== From: "Jingoo Han" To: "'Joao Pinto'" , "'Niklas Cassel'" , "'Lorenzo Pieralisi'" , "'Bjorn Helgaas'" Cc: "'Niklas Cassel'" , , References: <20171219232940.659-1-niklas.cassel@axis.com> <20171219232940.659-2-niklas.cassel@axis.com> In-Reply-To: Subject: Re: [PATCH v6 01/18] PCI: dwc: Use the DMA-API to get the MSI address Date: Thu, 21 Dec 2017 11:43:44 -0500 Message-ID: <000001d37a7a$ddc3c5b0$994b5110$@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQIEUapv8u3tCtMjYHwXXPyqK47qBQFgMCeZAhEnK76i0MdPUA== Content-Language: en-us Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id vBLGhsT8004085 Content-Length: 3340 Lines: 98 On Wednesday, December 20, 2017 2:10 PM, Joao Pinto wrote: > > Hi Niklas, > > Às 11:29 PM de 12/19/2017, Niklas Cassel escreveu: > > Use the DMA-API to get the MSI address. This address will be written to > > our PCI config space and to the register which determines which AXI > > address the DWC IP will spoof for incoming MSI irqs. > > > > Since it is a PCIe endpoint device, rather than the CPU, that is > supposed > > to write to the MSI address, the proper way to get the MSI address is by > > using the DMA API, not by using virt_to_phys(). > > > > Using virt_to_phys() might work on some systems, but using the DMA API > > should work on all systems. > > > > This is essentially the same thing as allocating a buffer in a driver > > to which the endpoint will write to. To do this, we use the DMA API. > > > > Signed-off-by: Niklas Cassel > > --- > > drivers/pci/dwc/pcie-designware-host.c | 15 ++++++++++++--- > > drivers/pci/dwc/pcie-designware.h | 3 ++- > > 2 files changed, 14 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/pci/dwc/pcie-designware-host.c > b/drivers/pci/dwc/pcie-designware-host.c > > index 81e2157a7cfb..bf558df5b7b3 100644 > > --- a/drivers/pci/dwc/pcie-designware-host.c > > +++ b/drivers/pci/dwc/pcie-designware-host.c > > @@ -83,10 +83,19 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp) > > > > void dw_pcie_msi_init(struct pcie_port *pp) > > { > > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); > > + struct device *dev = pci->dev; > > + struct page *page; > > u64 msi_target; > > > > - pp->msi_data = __get_free_pages(GFP_KERNEL, 0); > > - msi_target = virt_to_phys((void *)pp->msi_data); > > + page = alloc_page(GFP_KERNEL); > > + pp->msi_data = dma_map_page(dev, page, 0, PAGE_SIZE, > DMA_FROM_DEVICE); > > + if (dma_mapping_error(dev, pp->msi_data)) { > > + dev_err(dev, "failed to map MSI data\n"); > > + __free_page(page); > > + return; > > + } > > + msi_target = (u64)pp->msi_data; > > > > /* program the msi_data */ > > dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_LO, 4, > > @@ -187,7 +196,7 @@ static void dw_msi_setup_msg(struct pcie_port *pp, > unsigned int irq, u32 pos) > > if (pp->ops->get_msi_addr) > > msi_target = pp->ops->get_msi_addr(pp); > > else > > - msi_target = virt_to_phys((void *)pp->msi_data); > > + msi_target = (u64)pp->msi_data; > > > > msg.address_lo = (u32)(msi_target & 0xffffffff); > > msg.address_hi = (u32)(msi_target >> 32 & 0xffffffff); > > diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie- > designware.h > > index e5d9d77b778e..ecdede68522a 100644 > > --- a/drivers/pci/dwc/pcie-designware.h > > +++ b/drivers/pci/dwc/pcie-designware.h > > @@ -14,6 +14,7 @@ > > #ifndef _PCIE_DESIGNWARE_H > > #define _PCIE_DESIGNWARE_H > > > > +#include > > #include > > #include > > #include > > @@ -168,7 +169,7 @@ struct pcie_port { > > const struct dw_pcie_host_ops *ops; > > int msi_irq; > > struct irq_domain *irq_domain; > > - unsigned long msi_data; > > + dma_addr_t msi_data; > > DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS); > > }; > > > > > > Makes total sense! Thanks. > > Acked-by: Joao Pinto Acked-by: Jingoo Han Best regards, Jingoo Han