5a4b032078
The IPR drivers tests for MSI support at probe time with MSI vector 0
and when done, frees the IRQ with free_irq(). This test was introduced
by 95fecd90397e ("ipr: add test for MSI interrupt support") as an
improvement of commit 5a9ef25b14d3 ("[SCSI] ipr: add MSI support")
because a boot failure was reported on a Bimini PowerPC system:
https://lore.kernel.org/r/1242926159.3007.5.camel@localhost.localdomain
It was finally decided to remove MSI support on Bimini systems in
6eb0ac03899a ("powerpc/maple: Add a quirk to disable MSI for IPR on
Bimini").
Linux 5.15-rc1 added MSI domain support to the pseries machine and
when free_irq is called() in the driver, msi_domain_deactivate() also
is. This resets the MSI table entry of the associate vector by calling
__pci_write_msi_msg() with an empty message and breaks any further
activation of the same vector. In the case of the IPR driver, it
breaks the initialization sequence of the IOA.
Introduce an empty irq_write_msi_msg() handler in the MSI domain of
the pseries machine to avoid clearing the MSI vector entry. Updating
the entry is not strictly necessary since it is initialized by the
underlying hypervisor, PowerVM or QEMU/KVM.
Fixes: a5f3d2c17b07 ("powerpc/pseries/pci: Add MSI domains")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Tested-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
[mpe: Tweak comment wording and formatting slightly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210930102535.1047230-1-clg@kaod.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.