From: Bjorn Helgaas <helgaas@kernel.org>
To: Govinda Tatti <Govinda.Tatti@Oracle.COM>
Cc: jgross@suse.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
JBeulich@suse.com, bhelgaas@google.com,
xen-devel@lists.xenproject.org, boris.ostrovsky@Oracle.COM,
roger.pau@citrix.com
Subject: Re: [PATCH V3 1/2] Drivers/PCI: Export pcie_has_flr() interface
Date: Wed, 13 Dec 2017 15:24:21 -0600 [thread overview]
Message-ID: <20171213212420.GH30595__3285.30721967599$1513200339$gmane$org@bhelgaas-glaptop.roam.corp.google.com> (raw)
In-Reply-To: <49956aaf-5fd5-939d-5fc7-231ffdb98b70@Oracle.COM>
[+cc Christoph]
On Wed, Dec 13, 2017 at 02:46:57PM -0600, Govinda Tatti wrote:
>
> >>>>-static bool pcie_has_flr(struct pci_dev *dev)
> >>>>+bool pcie_has_flr(struct pci_dev *dev)
> >>>> {
> >>>> u32 cap;
> >>>>@@ -3882,6 +3882,7 @@ static bool pcie_has_flr(struct pci_dev *dev)
> >>>> pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
> >>>> return cap & PCI_EXP_DEVCAP_FLR;
> >>>> }
> >>>>+EXPORT_SYMBOL_GPL(pcie_has_flr);
> >>>I'd rather change pcie_flr() so you could *always* call it, and it
> >>>would return 0, -ENOTTY, or whatever, based on whether FLR is
> >>>supported. Is that feasible?
> >>Sure, I will add pcie_has_flr() logic inside pcie_flr() and return
> >>appropriate
> >>values as suggested by you. Do we still want to retain pcie_has_flr() and
> >>its usage inside pci.c?.Otherwise, I will remove it and do required cleanup.
> >If you can restructure the code and remove pcie_has_flr() while
> >retaining the existing behavior of its callers, that would be great.
> I checked the current usage of pcie_has_flr() and pcie_flr(). I have
> a couple
> of questions or need some clarification.
>
> 1. pcie_has_flr() usage inside pci_probe_reset_function().
>
> This function is only calling pcie_has_flr() but not pcie_flr().
> Rest of the code is trying to do specific type of reset except
> pcie_flr().
>
> rc = pci_dev_specific_reset(dev, 1);
> if (rc != -ENOTTY)
> return rc;
> if (pcie_has_flr(dev))
> return 0;
> rc = pci_af_flr(dev, 1);
> if (rc != -ENOTTY)
> return rc;
>
> In other-words, I can remove usage of pcie_has_flr() in all other places
> in pci.c except in above function.
I think we should keep the EXPORT_SYMBOL_GPL() part of a60a2b73ba69
("PCI: Export pcie_flr()"), but revert the restructuring part.
Prior to a60a2b73ba69, we had
int pcie_flr(struct pci_dev *dev, int probe);
like all the other reset methods. AFAICT, the addition of
pcie_has_flr() was to optimize the path slightly because when drivers
call pcie_flr(), they should already know that their hardware supports
FLR. But I don't think that optimization is worth the extra code
complexity. If we do need to optimize it, we can check this in the
core during enumeration and set PCI_DEV_FLAGS_NO_FLR_RESET
accordingly.
Christoph, chime in if I'm missing something here.
> 2. W.r.t pcie_flr(), I am planning to return error code. Currently,
> the following
> file/modules are calling this function. My plan is to add a check
> for return
> code and print a WANRING message if return code is NON-ZERO. I
> hope this is
> sufficient for this patch.
>
> drivers/crypto/qat/qat_common/adf_aer.c
> drivers/infiniband/hw/hfi1/chip.c (2 places)
> drivers/net/ethernet/cavium/liquidio/lio_vf_main.c
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c (2 places)
> drivers/pci/quirks.c (2 places)
Checking the return code is probably overkill, since pcie_flr() is
void and returns no errors now. The only point of the return value is
to tell whether the device supports FLR. If we call it with "probe ==
0" there's no useful error to return.
Bjorn
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next prev parent reply other threads:[~2017-12-13 21:24 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171207222145.9769-1-Govinda.Tatti@Oracle.COM>
2017-12-07 22:21 ` [PATCH V3 1/2] Drivers/PCI: Export pcie_has_flr() interface Govinda Tatti
2017-12-08 20:24 ` Bjorn Helgaas
[not found] ` <20171208202424.GC12367@bhelgaas-glaptop.roam.corp.google.com>
2017-12-12 0:29 ` Govinda Tatti
[not found] ` <426eeeab-0dcd-8de3-9c5f-a166acf2c130@Oracle.COM>
2017-12-12 0:59 ` Bjorn Helgaas
[not found] ` <20171212005919.GB30595@bhelgaas-glaptop.roam.corp.google.com>
2017-12-13 20:46 ` Govinda Tatti
[not found] ` <49956aaf-5fd5-939d-5fc7-231ffdb98b70@Oracle.COM>
2017-12-13 21:24 ` Bjorn Helgaas [this message]
[not found] ` <20171213212420.GH30595@bhelgaas-glaptop.roam.corp.google.com>
2017-12-14 12:52 ` Christoph Hellwig
[not found] ` <20171214125206.GA24958@infradead.org>
2017-12-15 0:24 ` Bjorn Helgaas
2017-12-15 15:48 ` Govinda Tatti
2017-12-15 18:18 ` Bjorn Helgaas
[not found] ` <20171215181801.GU30595@bhelgaas-glaptop.roam.corp.google.com>
2017-12-15 20:01 ` Govinda Tatti
2017-12-18 3:09 ` Alexey Kardashevskiy
2017-12-18 12:26 ` Christoph Hellwig
[not found] ` <20171218122629.GA18423@infradead.org>
2017-12-18 17:22 ` Govinda Tatti
2018-09-09 18:59 ` Pasi Kärkkäinen
[not found] ` <20180909185944.GC18222@reaktio.net>
2018-09-10 2:33 ` Sinan Kaya
[not found] ` <9ffe43d2-a44b-974c-85c9-9923d71c5dba@kernel.org>
2018-09-10 9:52 ` Pasi Kärkkäinen
[not found] ` <20180910095231.GD18222@reaktio.net>
2018-09-10 17:04 ` Sinan Kaya
2017-12-12 15:07 ` Christoph Hellwig
2017-12-07 22:21 ` [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute Govinda Tatti
[not found] ` <20171207222145.9769-3-Govinda.Tatti@Oracle.COM>
2017-12-08 9:34 ` Jan Beulich
2017-12-12 14:48 ` Govinda Tatti
2017-12-12 15:01 ` Jan Beulich
[not found] ` <5A2FFD690200007800196DFB@prv-mh.provo.novell.com>
2017-12-12 15:14 ` Govinda Tatti
2017-12-15 19:52 ` Govinda Tatti
[not found] ` <f19dbb09-ef22-2cf4-fb38-2a7c42b5dc48@Oracle.COM>
2017-12-18 7:36 ` Jan Beulich
[not found] ` <5A377E020200007800197FFA@prv-mh.provo.novell.com>
2017-12-18 17:32 ` Boris Ostrovsky
[not found] ` <559ffd12-b541-8a69-60bd-fbe10e3dc159@oracle.com>
2018-09-16 11:43 ` Pasi Kärkkäinen
[not found] ` <20180916114306.GF18222@reaktio.net>
2018-09-17 18:06 ` Boris Ostrovsky
[not found] ` <a726840b-8a5c-0890-73c6-3a95a7205153@oracle.com>
2018-09-18 7:15 ` Pasi Kärkkäinen
[not found] ` <20180918071519.GG18222@reaktio.net>
2018-09-18 9:32 ` George Dunlap
[not found] ` <5E7DDB68-4E68-48A5-AEEC-EE1B21A50E9E@citrix.com>
2018-09-18 18:09 ` Boris Ostrovsky
[not found] ` <352310b3-ec9b-2ceb-83f0-4550718120c3@oracle.com>
2018-09-19 9:05 ` Roger Pau Monné
[not found] ` <20180919090526.s3ahnemrt2ik2tx3@mac.bytemobile.com>
2018-10-03 15:51 ` Pasi Kärkkäinen
[not found] ` <20181003155104.GH5318@reaktio.net>
2018-10-08 14:32 ` Boris Ostrovsky
[not found] ` <f6b8e055-7afc-b4de-af88-425d799dcd28@oracle.com>
2018-10-23 18:40 ` Håkon Alstadheim
2018-10-29 15:30 ` Pasi Kärkkäinen
2018-11-14 14:24 ` [PATCH cargo-cult-version] For linux-4.19.x . " Håkon Alstadheim
2019-08-26 21:05 ` [Xen-devel] [PATCH V3 2/2] " Pasi Kärkkäinen
2017-12-12 15:01 ` Govinda Tatti
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