From: Amey Narkhede <ameynarkhede03@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: alex.williamson@redhat.com,
Raphael Norwitz <raphael.norwitz@nutanix.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
kw@linux.com, Shanker Donthineni <sdonthineni@nvidia.com>,
Sinan Kaya <okaya@kernel.org>, Len Brown <lenb@kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v7 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism
Date: Thu, 24 Jun 2021 20:42:42 +0530 [thread overview]
Message-ID: <20210624151242.ybew2z5rseuusj7v@archlinux> (raw)
In-Reply-To: <20210624121521.GA3518338@bjorn-Precision-5520>
On 21/06/24 07:15AM, Bjorn Helgaas wrote:
> On Tue, Jun 08, 2021 at 11:18:53AM +0530, Amey Narkhede wrote:
> > Add reset_method sysfs attribute to enable user to
> > query and set user preferred device reset methods and
> > their ordering.
>
> > + Writing the name or comma separated list of names of any of
> > + the device supported reset methods to this file will set the
> > + reset methods and their ordering to be used when resetting
> > + the device.
>
> > + while ((name = strsep(&options, ",")) != NULL) {
> > + if (sysfs_streq(name, ""))
> > + continue;
> > +
> > + name = strim(name);
> > +
> > + for (i = 0; i < PCI_RESET_METHODS_NUM; i++) {
> > + if (reset_methods[i] &&
> > + sysfs_streq(name, pci_reset_fn_methods[i].name)) {
> > + reset_methods[i] = prio--;
> > + break;
> > + }
> > + }
> > +
> > + if (i == PCI_RESET_METHODS_NUM) {
> > + kfree(options);
> > + return -EINVAL;
> > + }
> > + }
>
> Asking again since we didn't get this clarified before. The above
> tells me that "reset_methods" allows the user to control the *order*
> in which we try reset methods.
>
> Consider the following two uses:
>
> (1) # echo bus,flr > reset_methods
>
> (2) # echo flr,bus > reset_methods
>
> Do these have the same effect or not?
>
They have different effect.
> If "reset_methods" allows control over the order, I expect them to be
> different: (1) would try a bus reset and, if the bus reset failed, an
> FLR, while (2) would try an FLR and, if the FLR failed, a bus reset.
Exactly you are right.
Now the point I was presenting was with new encoding we have to write
list of *all of the supported reset methods* in order for example, in
above example flr,bus or bus,flr. We can't just write 'flr' or 'bus'
then switch back to writing flr,bus/bus,flr(these have different effect
as mentioned earlier).
Basically with new encoding an user can't write subset of reset methods
they have to write list of *all* supported methods everytime.
Thanks,
Amey
next prev parent reply other threads:[~2021-06-24 15:12 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-08 5:48 [PATCH v7 0/8] Expose and manage PCI device reset Amey Narkhede
2021-06-08 5:48 ` [PATCH v7 1/8] PCI: Add pcie_reset_flr to follow calling convention of other reset methods Amey Narkhede
2021-06-10 20:15 ` Shanker R Donthineni
2021-06-17 21:57 ` Bjorn Helgaas
2021-06-17 22:51 ` Alex Williamson
2021-06-18 16:32 ` Amey Narkhede
2021-06-24 12:23 ` Bjorn Helgaas
2021-06-24 15:28 ` Amey Narkhede
2021-06-24 16:15 ` Bjorn Helgaas
2021-06-24 18:48 ` Alex Williamson
2021-06-08 5:48 ` [PATCH v7 2/8] PCI: Add new array for keeping track of ordering of " Amey Narkhede
2021-06-10 20:15 ` Shanker R Donthineni
2021-06-17 23:13 ` Bjorn Helgaas
2021-06-18 17:22 ` Amey Narkhede
2021-06-21 15:02 ` Shanker R Donthineni
2021-06-21 17:15 ` Amey Narkhede
2021-06-21 18:37 ` Bjorn Helgaas
2021-06-08 5:48 ` [PATCH v7 3/8] PCI: Remove reset_fn field from pci_dev Amey Narkhede
2021-06-10 20:16 ` Shanker R Donthineni
2021-06-08 5:48 ` [PATCH v7 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism Amey Narkhede
2021-06-09 21:57 ` Raphael Norwitz
2021-06-09 22:36 ` Shanker R Donthineni
2021-06-09 22:48 ` Raphael Norwitz
2021-06-10 20:16 ` Shanker R Donthineni
2021-06-18 20:00 ` Bjorn Helgaas
2021-06-19 13:59 ` Amey Narkhede
2021-06-21 13:01 ` Bjorn Helgaas
2021-06-21 17:28 ` Amey Narkhede
2021-06-21 19:07 ` Bjorn Helgaas
2021-06-21 19:33 ` Amey Narkhede
2021-06-23 12:06 ` Bjorn Helgaas
2021-06-23 14:07 ` Amey Narkhede
2021-06-23 17:56 ` Amey Narkhede
2021-06-23 17:21 ` Alex Williamson
2021-06-24 12:15 ` Bjorn Helgaas
2021-06-24 15:12 ` Amey Narkhede [this message]
2021-06-24 16:56 ` Bjorn Helgaas
2021-06-24 17:20 ` Shanker R Donthineni
2021-06-24 17:28 ` Amey Narkhede
2021-06-24 17:59 ` Bjorn Helgaas
2021-06-08 5:48 ` [PATCH v7 5/8] PCI: Setup ACPI_COMPANION early Amey Narkhede
2021-06-08 5:48 ` [PATCH v7 6/8] PCI: Add support for ACPI _RST reset method Amey Narkhede
2021-06-08 5:48 ` [PATCH v7 7/8] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs Amey Narkhede
2021-06-10 23:16 ` Bjorn Helgaas
2021-06-10 23:33 ` Shanker R Donthineni
2021-06-10 23:43 ` Shanker R Donthineni
2021-06-10 23:53 ` Bjorn Helgaas
2021-06-11 4:15 ` Shanker R Donthineni
2021-06-08 5:48 ` [PATCH v7 8/8] PCI: Change the type of probe argument in reset functions Amey Narkhede
2021-06-09 21:40 ` Raphael Norwitz
2021-06-08 10:05 ` [PATCH v7 0/8] Expose and manage PCI device reset Enrico Weigelt, metux IT consult
2021-06-08 15:44 ` Amey Narkhede
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