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Message-ID: <1484785188.2406.73.camel@redhat.com>
Date: Wed, 18 Jan 2017 19:19:48 -0500
From: Doug Ledford <dledford@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>, linux-kernel@...r.kernel.org
Cc: Linas Vepstas <linasvepstas@...il.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Jonathan Corbet <corbet@....net>,
Mike Marciniszyn <mike.marciniszyn@...el.com>,
Dennis Dalessandro <dennis.dalessandro@...el.com>,
Sean Hefty <sean.hefty@...el.com>,
Hal Rosenstock <hal.rosenstock@...il.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-pci@...r.kernel.org, linux-doc@...r.kernel.org,
linux-rdma@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH] pci: drop link_reset
On Wed, 2017-01-18 at 23:39 +0200, Michael S. Tsirkin wrote:
> No hardware seems to actually call link_reset, and
> no driver implements it as more than a nop stub.
>
> This drops the mentions of the callback from everywhere.
> It's dropped from the documentation as well, but
> the doc really needs to be updated to reflect
> reality better (e.g. on pcie slot reset is the link reset).
>
> This will be done in a later patch.
>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
This is going to conflict with the two patches I have in my for-next
branch related to this same thing (it drops the stubs from qib and
hfi1). It would be easiest if I just added this to my for-next and
fixed up the conflicts prior to submission.
> ---
> Documentation/PCI/pci-error-recovery.txt | 24 +++-------------------
> --
> drivers/infiniband/hw/hfi1/pcie.c | 10 ----------
> drivers/infiniband/hw/qib/qib_pcie.c | 8 --------
> drivers/media/pci/ngene/ngene-cards.c | 7 -------
> include/linux/pci.h | 3 ---
> 5 files changed, 3 insertions(+), 49 deletions(-)
>
> diff --git a/Documentation/PCI/pci-error-recovery.txt
> b/Documentation/PCI/pci-error-recovery.txt
> index ac26869..da3b217 100644
> --- a/Documentation/PCI/pci-error-recovery.txt
> +++ b/Documentation/PCI/pci-error-recovery.txt
> @@ -78,7 +78,6 @@ struct pci_error_handlers
> {
> int (*error_detected)(struct pci_dev *dev, enum
> pci_channel_state);
> int (*mmio_enabled)(struct pci_dev *dev);
> - int (*link_reset)(struct pci_dev *dev);
> int (*slot_reset)(struct pci_dev *dev);
> void (*resume)(struct pci_dev *dev);
> };
> @@ -104,8 +103,7 @@ if it implements any, it must implement
> error_detected(). If a callback
> is not implemented, the corresponding feature is considered
> unsupported.
> For example, if mmio_enabled() and resume() aren't there, then it
> is assumed that the driver is not doing any direct recovery and
> requires
> -a slot reset. If link_reset() is not implemented, the card is
> assumed to
> -not care about link resets. Typically a driver will want to know
> about
> +a slot reset. Typically a driver will want to know about
> a slot_reset().
>
> The actual steps taken by a platform to recover from a PCI error
> @@ -232,25 +230,9 @@ proceeds to STEP 4 (Slot Reset)
>
> STEP 3: Link Reset
> ------------------
> -The platform resets the link, and then calls the link_reset()
> callback
> -on all affected device drivers. This is a PCI-Express specific
> state
> +The platform resets the link. This is a PCI-Express specific step
> and is done whenever a non-fatal error has been detected that can be
> -"solved" by resetting the link. This call informs the driver of the
> -reset and the driver should check to see if the device appears to be
> -in working condition.
> -
> -The driver is not supposed to restart normal driver I/O operations
> -at this point. It should limit itself to "probing" the device to
> -check its recoverability status. If all is right, then the platform
> -will call resume() once all drivers have ack'd link_reset().
> -
> - Result codes:
> - (identical to STEP 3 (MMIO Enabled)
> -
> -The platform then proceeds to either STEP 4 (Slot Reset) or STEP 5
> -(Resume Operations).
> -
> ->>> The current powerpc implementation does not implement this
> callback.
> +"solved" by resetting the link.
>
> STEP 4: Slot Reset
> ------------------
> diff --git a/drivers/infiniband/hw/hfi1/pcie.c
> b/drivers/infiniband/hw/hfi1/pcie.c
> index 4ac8f33..ebd941f 100644
> --- a/drivers/infiniband/hw/hfi1/pcie.c
> +++ b/drivers/infiniband/hw/hfi1/pcie.c
> @@ -598,15 +598,6 @@ pci_slot_reset(struct pci_dev *pdev)
> return PCI_ERS_RESULT_CAN_RECOVER;
> }
>
> -static pci_ers_result_t
> -pci_link_reset(struct pci_dev *pdev)
> -{
> - struct hfi1_devdata *dd = pci_get_drvdata(pdev);
> -
> - dd_dev_info(dd, "HFI1 link_reset function called,
> ignored\n");
> - return PCI_ERS_RESULT_CAN_RECOVER;
> -}
> -
> static void
> pci_resume(struct pci_dev *pdev)
> {
> @@ -625,7 +616,6 @@ pci_resume(struct pci_dev *pdev)
> const struct pci_error_handlers hfi1_pci_err_handler = {
> .error_detected = pci_error_detected,
> .mmio_enabled = pci_mmio_enabled,
> - .link_reset = pci_link_reset,
> .slot_reset = pci_slot_reset,
> .resume = pci_resume,
> };
> diff --git a/drivers/infiniband/hw/qib/qib_pcie.c
> b/drivers/infiniband/hw/qib/qib_pcie.c
> index 6abe1c6..c379b83 100644
> --- a/drivers/infiniband/hw/qib/qib_pcie.c
> +++ b/drivers/infiniband/hw/qib/qib_pcie.c
> @@ -682,13 +682,6 @@ qib_pci_slot_reset(struct pci_dev *pdev)
> return PCI_ERS_RESULT_CAN_RECOVER;
> }
>
> -static pci_ers_result_t
> -qib_pci_link_reset(struct pci_dev *pdev)
> -{
> - qib_devinfo(pdev, "QIB link_reset function called,
> ignored\n");
> - return PCI_ERS_RESULT_CAN_RECOVER;
> -}
> -
> static void
> qib_pci_resume(struct pci_dev *pdev)
> {
> @@ -707,7 +700,6 @@ qib_pci_resume(struct pci_dev *pdev)
> const struct pci_error_handlers qib_pci_err_handler = {
> .error_detected = qib_pci_error_detected,
> .mmio_enabled = qib_pci_mmio_enabled,
> - .link_reset = qib_pci_link_reset,
> .slot_reset = qib_pci_slot_reset,
> .resume = qib_pci_resume,
> };
> diff --git a/drivers/media/pci/ngene/ngene-cards.c
> b/drivers/media/pci/ngene/ngene-cards.c
> index 423e8c8..8438c1c 100644
> --- a/drivers/media/pci/ngene/ngene-cards.c
> +++ b/drivers/media/pci/ngene/ngene-cards.c
> @@ -781,12 +781,6 @@ static pci_ers_result_t
> ngene_error_detected(struct pci_dev *dev,
> return PCI_ERS_RESULT_CAN_RECOVER;
> }
>
> -static pci_ers_result_t ngene_link_reset(struct pci_dev *dev)
> -{
> - printk(KERN_INFO DEVICE_NAME ": link reset\n");
> - return 0;
> -}
> -
> static pci_ers_result_t ngene_slot_reset(struct pci_dev *dev)
> {
> printk(KERN_INFO DEVICE_NAME ": slot reset\n");
> @@ -800,7 +794,6 @@ static void ngene_resume(struct pci_dev *dev)
>
> static const struct pci_error_handlers ngene_errors = {
> .error_detected = ngene_error_detected,
> - .link_reset = ngene_link_reset,
> .slot_reset = ngene_slot_reset,
> .resume = ngene_resume,
> };
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 30d6c16..316379c 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -661,9 +661,6 @@ struct pci_error_handlers {
> /* MMIO has been re-enabled, but not DMA */
> pci_ers_result_t (*mmio_enabled)(struct pci_dev *dev);
>
> - /* PCI Express link has been reset */
> - pci_ers_result_t (*link_reset)(struct pci_dev *dev);
> -
> /* PCI slot has been reset */
> pci_ers_result_t (*slot_reset)(struct pci_dev *dev);
>
--
Doug Ledford <dledford@...hat.com>
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