[PATCH v2 1/1] RDMA/hfi1: Use RMW accessors for changing LNKCTL2

[PATCH v2 1/1] RDMA/hfi1: Use RMW accessors for changing LNKCTL2

[Ilpo Järvinen]

Convert open coded RMW accesses for LNKCTL2 to use
pcie_capability_clear_and_set_word() which makes its easier to
understand what the code tries to do.

In addition, this futureproofs the code. LNKCTL2 is not really owned by
any driver because it is a collection of control bits that PCI core
might need to touch. RMW accessors already have support for proper
locking for a selected set of registers to avoid losing concurrent
updates (LNKCTL2 is not yet among the registers that need protection
but likely will be in the future).

Suggested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Dean Luick <dean.luick@cornelisnetworks.com>
---

This was part of other series earlier but sending this indenpendent now
to not appear to be part of a cross subsystem series.

v2:
- Small improvements into the commit message

 drivers/infiniband/hw/hfi1/pcie.c | 30 ++++++++----------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/pcie.c b/drivers/infiniband/hw/hfi1/pcie.c
index 119ec2f1382b..7133964749f8 100644
--- a/drivers/infiniband/hw/hfi1/pcie.c
+++ b/drivers/infiniband/hw/hfi1/pcie.c
@@ -1207,14 +1207,11 @@ int do_pcie_gen3_transition(struct hfi1_devdata *dd)
 		    (u32)lnkctl2);
 	/* only write to parent if target is not as high as ours */
 	if ((lnkctl2 & PCI_EXP_LNKCTL2_TLS) < target_vector) {
-		lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
-		lnkctl2 |= target_vector;
-		dd_dev_info(dd, "%s: ..new link control2: 0x%x\n", __func__,
-			    (u32)lnkctl2);
-		ret = pcie_capability_write_word(parent,
-						 PCI_EXP_LNKCTL2, lnkctl2);
+		ret = pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL2,
+							 PCI_EXP_LNKCTL2_TLS,
+							 target_vector);
 		if (ret) {
-			dd_dev_err(dd, "Unable to write to PCI config\n");
+			dd_dev_err(dd, "Unable to change parent PCI target speed\n");
 			return_error = 1;
 			goto done;
 		}
@@ -1223,22 +1220,11 @@ int do_pcie_gen3_transition(struct hfi1_devdata *dd)
 	}
 
 	dd_dev_info(dd, "%s: setting target link speed\n", __func__);
-	ret = pcie_capability_read_word(dd->pcidev, PCI_EXP_LNKCTL2, &lnkctl2);
+	ret = pcie_capability_clear_and_set_word(dd->pcidev, PCI_EXP_LNKCTL2,
+						 PCI_EXP_LNKCTL2_TLS,
+						 target_vector);
 	if (ret) {
-		dd_dev_err(dd, "Unable to read from PCI config\n");
-		return_error = 1;
-		goto done;
-	}
-
-	dd_dev_info(dd, "%s: ..old link control2: 0x%x\n", __func__,
-		    (u32)lnkctl2);
-	lnkctl2 &= ~PCI_EXP_LNKCTL2_TLS;
-	lnkctl2 |= target_vector;
-	dd_dev_info(dd, "%s: ..new link control2: 0x%x\n", __func__,
-		    (u32)lnkctl2);
-	ret = pcie_capability_write_word(dd->pcidev, PCI_EXP_LNKCTL2, lnkctl2);
-	if (ret) {
-		dd_dev_err(dd, "Unable to write to PCI config\n");
+		dd_dev_err(dd, "Unable to change device PCI target speed\n");
 		return_error = 1;
 		goto done;
 	}
-- 
2.39.2

Re: [PATCH v2 1/1] RDMA/hfi1: Use RMW accessors for changing LNKCTL2

[Leon Romanovsky]

On Fri, 03 May 2024 16:36:40 +0300, Ilpo Järvinen wrote:
> Convert open coded RMW accesses for LNKCTL2 to use
> pcie_capability_clear_and_set_word() which makes its easier to
> understand what the code tries to do.
> 
> In addition, this futureproofs the code. LNKCTL2 is not really owned by
> any driver because it is a collection of control bits that PCI core
> might need to touch. RMW accessors already have support for proper
> locking for a selected set of registers to avoid losing concurrent
> updates (LNKCTL2 is not yet among the registers that need protection
> but likely will be in the future).
> 
> [...]

Applied, thanks!

[1/1] RDMA/hfi1: Use RMW accessors for changing LNKCTL2
      https://git.kernel.org/rdma/rdma/c/8f3b7103b41314

Best regards,
-- 
Leon Romanovsky <leon@kernel.org>