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Date:   Tue, 24 Jan 2017 19:35:56 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     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>,
        Doug Ledford <dledford@...hat.com>,
        Sean Hefty <sean.hefty@...el.com>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Frank Haverkamp <haver@...ux.vnet.ibm.com>,
        Gabriel Krisman Bertazi <krisman@...ux.vnet.ibm.com>,
        linux-pci@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-media@...r.kernel.org
Subject: [PATCH v2] pci: drop link_reset

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>
---

changes from v2:
	- drop from genwqe as well

Note: Doug has patches dropping the implementation from infiniband card
drivers in his tree already. This is unlikely to cause conflicts though.

 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 -------
 drivers/misc/genwqe/card_base.c          |  1 -
 include/linux/pci.h                      |  3 ---
 6 files changed, 3 insertions(+), 50 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/drivers/misc/genwqe/card_base.c b/drivers/misc/genwqe/card_base.c
index 6c1f49a..4fd21e8 100644
--- a/drivers/misc/genwqe/card_base.c
+++ b/drivers/misc/genwqe/card_base.c
@@ -1336,7 +1336,6 @@ static int genwqe_sriov_configure(struct pci_dev *dev, int numvfs)
 static struct pci_error_handlers genwqe_err_handler = {
 	.error_detected = genwqe_err_error_detected,
 	.mmio_enabled	= genwqe_err_result_none,
-	.link_reset	= genwqe_err_result_none,
 	.slot_reset	= genwqe_err_slot_reset,
 	.resume		= genwqe_err_resume,
 };
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e2d1a12..2c0158b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -678,9 +678,6 @@ 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);
 
-- 
MST

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