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irq_find_mapping() does not need irq_dispose_mapping(), only irq_create_mapping() does. Calling irq_dispose_mapping() from mv88e6xxx_g2_irq_mdio_free() and from the error path of mv88e6xxx_g2_irq_mdio_setup() effectively means that the mdiobus logic (for internal PHY interrupts) is disposing of a hwirq->virq mapping which it is not responsible of (but instead, the function pair mv88e6xxx_g2_irq_setup() + mv88e6xxx_g2_irq_free() is). With the current code structure, this isn't such a huge problem, because mv88e6xxx_g2_irq_mdio_free() is called relatively close to the real owner of the IRQ mappings: mv88e6xxx_remove() -> mv88e6xxx_unregister_switch() -> mv88e6xxx_mdios_unregister() -> mv88e6xxx_g2_irq_mdio_free() -> mv88e6xxx_g2_irq_free() and the switch isn't 'live' in any way such that it would be able of generating interrupts at this point (mv88e6xxx_unregister_switch() has been called). However, there is a desire to split mv88e6xxx_mdios_unregister() and mv88e6xxx_g2_irq_free() such that mv88e6xxx_mdios_unregister() only gets called from mv88e6xxx_teardown(). This is much more problematic, as can be seen below. In a cross-chip scenario (say 3 switches d0032004.mdio-mii:10, d0032004.mdio-mii:11 and d0032004.mdio-mii:12 which form a single DSA tree), it is possible to unbind the device driver from a single switch (say d0032004.mdio-mii:10). When that happens, mv88e6xxx_remove() will be called for just that one switch, and this will call mv88e6xxx_unregister_switch() which will tear down the entire tree (calling mv88e6xxx_teardown() for all 3 switches). Assuming mv88e6xxx_mdios_unregister() was moved to mv88e6xxx_teardown(), at this stage, all 3 switches will have called irq_dispose_mapping() on their mdiobus virqs. When we bind again the device driver to d0032004.mdio-mii:10, mv88e6xxx_probe() is called for it, which calls dsa_register_switch(). The DSA tree is now complete again, and mv88e6xxx_setup() is called for all 3 switches. Also assuming that mv88e6xxx_mdios_register() is moved to mv88e6xxx_setup() (the 2 assumptions go together), at this point, d0032004.mdio-mii:11 and d0032004.mdio-mii:12 don't have an IRQ mapping for the internal PHYs anymore, as they've disposed of it in mv88e6xxx_teardown(). Whereas switch d0032004.mdio-mii:10 has re-created it, because its code path comes from mv88e6xxx_probe(). Simply put, this change prepares the driver to handle the movement of mv88e6xxx_mdios_register() to mv88e6xxx_setup() for cross-chip DSA trees. Also, the code being deleted was partially wrong anyway (in a way which may have hidden this other issue). mv88e6xxx_g2_irq_mdio_setup() populates bus->irq[] starting with offset chip->info->phy_base_addr, but the teardown path doesn't apply that offset too. So it disposes of virq 0 for phy = [ 0, phy_base_addr ). All switch families have phy_base_addr = 0, except for MV88E6141 and MV88E6341 which have it as 0x10. I guess those families would have happened to work by mistake in cross-chip scenarios too. I'm deleting the body of mv88e6xxx_g2_irq_mdio_free() but leaving its call sites and prototype in place. This is because, if we ever need to add back some teardown procedure in the future, it will be perhaps error-prone to deduce the proper call sites again. Whereas like this, no extra code should get generated, it shouldn't bother anybody. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: Klaus Kudielka <klaus.kudielka@gmail.com> Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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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.