linux-kernel - Re: [PATCH 06/17] IB/hfi1: Use pcie_lnkctl{,2}_clear_and

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Message-ID: <1b4ebce-1fcb-90e0-6396-967a5b6d563e@linux.intel.com>
Date:   Thu, 11 May 2023 23:02:12 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Dean Luick <dean.luick@...nelisnetworks.com>
cc:     linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Lukas Wunner <lukas@...ner.de>,
        Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>, linux-rdma@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 06/17] IB/hfi1: Use pcie_lnkctl{,2}_clear_and_set() for
 changing LNKCTL{,2}

On Thu, 11 May 2023, Dean Luick wrote:

> On 5/11/2023 8:14 AM, Ilpo Järvinen wrote:
> > Don't assume that only the driver would be accessing LNKCTL/LNKCTL2.
> > ASPM policy changes can trigger write to LNKCTL outside of driver's
> > control. And in the case of upstream (parent), the driver does not even
> > own the device it's changing the registers for.
> >
> > Use pcie_lnkctl_clear_and_set() and pcie_lnkctl2_clear_and_set() which
> > do proper locking to avoid losing concurrent updates to the register
> > value.
> >
> > Suggested-by: Lukas Wunner <lukas@...ner.de>
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> > ---

> > diff --git a/drivers/infiniband/hw/hfi1/pcie.c b/drivers/infiniband/hw/hfi1/pcie.c
> > index 08732e1ac966..fe7324d38d64 100644
> > --- a/drivers/infiniband/hw/hfi1/pcie.c
> > +++ b/drivers/infiniband/hw/hfi1/pcie.c
> > @@ -1212,14 +1212,10 @@ 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);
> > +             pcie_lnkctl2_clear_and_set(parent, PCI_EXP_LNKCTL2_TLS,
> > +                                        target_vector);
> 
> You are missing an assignment to "ret" above.

Thanks for noticing, I'll fix it in the next version.

-- 
 i.