From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sinan Kaya Subject: Re: [PATCH V3 2/2] PCI: handle CRS returned by device after FLR Date: Tue, 21 Feb 2017 12:04:24 -0500 Message-ID: References: <1475473021-14251-1-git-send-email-okaya@codeaurora.org> <1475473021-14251-3-git-send-email-okaya@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:45884 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752022AbdBURE2 (ORCPT ); Tue, 21 Feb 2017 12:04:28 -0500 In-Reply-To: <1475473021-14251-3-git-send-email-okaya@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: linux-pci@vger.kernel.org, alex.williamson@redhat.com Cc: timur@codeaurora.org, cov@codeaurora.org, vikrams@codeaurora.org, Lorenzo.Pieralisi@arm.com, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Hi Alex, I'm coming back to work on this. On 10/3/2016 1:37 AM, Sinan Kaya wrote: > An endpoint is allowed to issue CRS following an FLR request to indicate > that it is not ready to accept new requests. Changing the polling mechanism > in FLR wait function to go read the vendor ID instead of the command/status > register. A CRS indication will only be given if the address to be read is > vendor ID. > > Signed-off-by: Sinan Kaya > --- > drivers/pci/pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index c8749b9..7580b00 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3725,7 +3725,8 @@ static void pci_flr_wait(struct pci_dev *dev) > > do { > msleep(100); > - pci_read_config_dword(dev, PCI_COMMAND, &id); Your comment here puzzled me. https://patchwork.kernel.org/patch/8331851/ "Self nak on this one, didn't account for VFs not implementing the first dword. Thanks," I'm trying to add Configuration Request Retry Status (CRS) support to FLR with this patch. Basically, the root port will return 0xFFFF0001 only when a config read request is sent to the vendor ID register and CRS visibility is set. The SW needs to poll until this special read ID disappears. See the implementation note on Configuration Request Retry Status in PCIE specification for details. pci_bus_read_dev_vendor_id implements this loop for us. You are saying that there are VFs that do not implement vendor ID register. Can you give some history on this? > + pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &id, > + 60 * 1000); > } while (i++ < 10 && id == ~0); > > if (id == ~0) > Sinan -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Re: [PATCH V3 2/2] PCI: handle CRS returned by device after FLR To: linux-pci@vger.kernel.org, alex.williamson@redhat.com References: <1475473021-14251-1-git-send-email-okaya@codeaurora.org> <1475473021-14251-3-git-send-email-okaya@codeaurora.org> From: Sinan Kaya Message-ID: Date: Tue, 21 Feb 2017 12:04:24 -0500 MIME-Version: 1.0 In-Reply-To: <1475473021-14251-3-git-send-email-okaya@codeaurora.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo.Pieralisi@arm.com, vikrams@codeaurora.org, linux-arm-msm@vger.kernel.org, timur@codeaurora.org, linux-kernel@vger.kernel.org, cov@codeaurora.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: Hi Alex, I'm coming back to work on this. On 10/3/2016 1:37 AM, Sinan Kaya wrote: > An endpoint is allowed to issue CRS following an FLR request to indicate > that it is not ready to accept new requests. Changing the polling mechanism > in FLR wait function to go read the vendor ID instead of the command/status > register. A CRS indication will only be given if the address to be read is > vendor ID. > > Signed-off-by: Sinan Kaya > --- > drivers/pci/pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index c8749b9..7580b00 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3725,7 +3725,8 @@ static void pci_flr_wait(struct pci_dev *dev) > > do { > msleep(100); > - pci_read_config_dword(dev, PCI_COMMAND, &id); Your comment here puzzled me. https://patchwork.kernel.org/patch/8331851/ "Self nak on this one, didn't account for VFs not implementing the first dword. Thanks," I'm trying to add Configuration Request Retry Status (CRS) support to FLR with this patch. Basically, the root port will return 0xFFFF0001 only when a config read request is sent to the vendor ID register and CRS visibility is set. The SW needs to poll until this special read ID disappears. See the implementation note on Configuration Request Retry Status in PCIE specification for details. pci_bus_read_dev_vendor_id implements this loop for us. You are saying that there are VFs that do not implement vendor ID register. Can you give some history on this? > + pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &id, > + 60 * 1000); > } while (i++ < 10 && id == ~0); > > if (id == ~0) > Sinan -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: okaya@codeaurora.org (Sinan Kaya) Date: Tue, 21 Feb 2017 12:04:24 -0500 Subject: [PATCH V3 2/2] PCI: handle CRS returned by device after FLR In-Reply-To: <1475473021-14251-3-git-send-email-okaya@codeaurora.org> References: <1475473021-14251-1-git-send-email-okaya@codeaurora.org> <1475473021-14251-3-git-send-email-okaya@codeaurora.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Alex, I'm coming back to work on this. On 10/3/2016 1:37 AM, Sinan Kaya wrote: > An endpoint is allowed to issue CRS following an FLR request to indicate > that it is not ready to accept new requests. Changing the polling mechanism > in FLR wait function to go read the vendor ID instead of the command/status > register. A CRS indication will only be given if the address to be read is > vendor ID. > > Signed-off-by: Sinan Kaya > --- > drivers/pci/pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index c8749b9..7580b00 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3725,7 +3725,8 @@ static void pci_flr_wait(struct pci_dev *dev) > > do { > msleep(100); > - pci_read_config_dword(dev, PCI_COMMAND, &id); Your comment here puzzled me. https://patchwork.kernel.org/patch/8331851/ "Self nak on this one, didn't account for VFs not implementing the first dword. Thanks," I'm trying to add Configuration Request Retry Status (CRS) support to FLR with this patch. Basically, the root port will return 0xFFFF0001 only when a config read request is sent to the vendor ID register and CRS visibility is set. The SW needs to poll until this special read ID disappears. See the implementation note on Configuration Request Retry Status in PCIE specification for details. pci_bus_read_dev_vendor_id implements this loop for us. You are saying that there are VFs that do not implement vendor ID register. Can you give some history on this? > + pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &id, > + 60 * 1000); > } while (i++ < 10 && id == ~0); > > if (id == ~0) > Sinan -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.