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Message-Id: <1384993290-10107-2-git-send-email-jon.mason@intel.com>
Date: Wed, 20 Nov 2013 17:21:22 -0700
From: Jon Mason <jon.mason@...el.com>
To: linux-kernel@...r.kernel.org
Subject: [PATCH 1/9] NTB: Xeon Doorbell errata workaround
Modifications to the 14th bit of the B2BDOORBELL register will not be
mirrored to the remote system due to a hardware issue. To get around
the issue, shrink the number of available doorbell bits by 1. The max
number of doorbells was being used as a way to referencing the Link
Doorbell bit. Since this would no longer work, the driver must now
explicitly reference that bit.
This does not affect the xeon_errata_workaround case, as it is not using
the b2bdoorbell register.
Signed-off-by: Jon Mason <jon.mason@...el.com>
---
drivers/ntb/ntb_hw.c | 20 +++++++++++++++-----
drivers/ntb/ntb_regs.h | 1 +
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
index 1cb6e51..6c9d733 100644
--- a/drivers/ntb/ntb_hw.c
+++ b/drivers/ntb/ntb_hw.c
@@ -678,6 +678,7 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
return -EINVAL;
ndev->limits.max_mw = SNB_ERRATA_MAX_MW;
+ ndev->limits.max_db_bits = SNB_MAX_DB_BITS;
ndev->reg_ofs.spad_write = ndev->mw[1].vbase +
SNB_SPAD_OFFSET;
ndev->reg_ofs.rdb = ndev->mw[1].vbase +
@@ -690,6 +691,13 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
SNB_PBAR4LMT_OFFSET);
} else {
ndev->limits.max_mw = SNB_MAX_MW;
+
+ /* HW Errata on bit 14 of b2bdoorbell register. Writes
+ * will not be mirrored to the remote system. Shrink
+ * the number of bits by one, since bit 14 is the last
+ * bit.
+ */
+ ndev->limits.max_db_bits = SNB_MAX_DB_BITS - 1;
ndev->reg_ofs.spad_write = ndev->reg_base +
SNB_B2B_SPAD_OFFSET;
ndev->reg_ofs.rdb = ndev->reg_base +
@@ -769,6 +777,7 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
* have an equal amount.
*/
ndev->limits.max_spads = SNB_MAX_COMPAT_SPADS / 2;
+ ndev->limits.max_db_bits = SNB_MAX_DB_BITS;
/* Note: The SDOORBELL is the cause of the errata. You REALLY
* don't want to touch it.
*/
@@ -793,6 +802,7 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
* have an equal amount.
*/
ndev->limits.max_spads = SNB_MAX_COMPAT_SPADS / 2;
+ ndev->limits.max_db_bits = SNB_MAX_DB_BITS;
ndev->reg_ofs.rdb = ndev->reg_base + SNB_PDOORBELL_OFFSET;
ndev->reg_ofs.ldb = ndev->reg_base + SNB_SDOORBELL_OFFSET;
ndev->reg_ofs.ldb_mask = ndev->reg_base + SNB_SDBMSK_OFFSET;
@@ -819,7 +829,6 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
ndev->reg_ofs.lnk_stat = ndev->reg_base + SNB_SLINK_STATUS_OFFSET;
ndev->reg_ofs.spci_cmd = ndev->reg_base + SNB_PCICMD_OFFSET;
- ndev->limits.max_db_bits = SNB_MAX_DB_BITS;
ndev->limits.msix_cnt = SNB_MSIX_CNT;
ndev->bits_per_vector = SNB_DB_BITS_PER_VEC;
@@ -986,7 +995,7 @@ static irqreturn_t xeon_event_msix_irq(int irq, void *dev)
dev_err(&ndev->pdev->dev, "Error determining link status\n");
/* bit 15 is always the link bit */
- writew(1 << ndev->limits.max_db_bits, ndev->reg_ofs.ldb);
+ writew(1 << SNB_LINK_DB, ndev->reg_ofs.ldb);
return IRQ_HANDLED;
}
@@ -1176,9 +1185,10 @@ static int ntb_setup_interrupts(struct ntb_device *ndev)
*/
if (ndev->hw_type == BWD_HW)
writeq(~0, ndev->reg_ofs.ldb_mask);
- else
- writew(~(1 << ndev->limits.max_db_bits),
- ndev->reg_ofs.ldb_mask);
+ else {
+ u16 var = 1 << SNB_LINK_DB;
+ writew(~var, ndev->reg_ofs.ldb_mask);
+ }
rc = ntb_setup_msix(ndev);
if (!rc)
diff --git a/drivers/ntb/ntb_regs.h b/drivers/ntb/ntb_regs.h
index aa4bdd3..5381b65 100644
--- a/drivers/ntb/ntb_regs.h
+++ b/drivers/ntb/ntb_regs.h
@@ -55,6 +55,7 @@
#define SNB_MAX_COMPAT_SPADS 16
/* Reserve the uppermost bit for link interrupt */
#define SNB_MAX_DB_BITS 15
+#define SNB_LINK_DB 15
#define SNB_DB_BITS_PER_VEC 5
#define SNB_MAX_MW 2
#define SNB_ERRATA_MAX_MW 1
--
1.7.9.5
--
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