Re: [PATCH v3 04/10] RDMA/hfi1: Use RMW accessors for changing LNKCTL2

Dean Luick
2023-09-29T13:03:18Z

On 9/29/2023 6:57 AM, Ilpo Järvinen wrote:
> Don't assume that only the driver would be accessing LNKCTL2. In the
> case of upstream (parent), the driver does not even own the device it's
> changing the registers for.
>
> Use RMW capability accessors which do proper locking to avoid losing
> concurrent updates to the register value. This change is also useful as
> a cleanup.
>
> Suggested-by: Lukas Wunner <lukas@wunner.de>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---
> 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 08732e1ac966..4487a05bea04 100644
> --- a/drivers/infiniband/hw/hfi1/pcie.c
> +++ b/drivers/infiniband/hw/hfi1/pcie.c
> @@ -1212,14 +1212,11 @@ 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;
> }
> @@ -1228,22 +1225,11 @@ 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;
> }

Looks good. Thank you for my suggested changes.

Reviewed-by: Dean Luick <dean.luick@cornelisnetworks.com>

-Dean

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