[PATCH 0/9] Macintosh II ADB driver fixes

Finn Thain
2020-06-28T04:31:46Z

Various issues with the via-macii driver have become apparent over the
years. Some examples:

- A Talk command response can be lost. This can result in phantom devices
being probed or an incorrect device handler ID being retrieved.

- A reply packet containing a null byte can get truncated. Such packets
are sometimes generated by ADB keyboards.

- A Talk Register 3 reply from device 15 (that is, command byte 0xFF)
can be mistaken for a bus timeout (empty packet).

This patch series contains fixes for all known bugs in the via-macii
driver, plus a few code style improvements. It has been successfully
tested on an Apple Centris 650 and qemu-system-m68k.

The patched kernel does regress on past QEMU releases, due to ADB
transceiver emulation bugs. Those bugs have been fixed in mainline QEMU.
My thanks go to Mark Cave-Ayland for that effort and for figuring out
the improvements to the signalling between the VIA and the transceiver.

Note to -stable maintainers: these fixes can be cherry-picked without
difficulty, if you have the 5 commits that appeared in v5.0:

b52dce8738938 macintosh/via-macii: Synchronous bus reset
5f93d7081a47e macintosh/via-macii: Remove BUG_ON assertions
5ce6185c2ef4e macintosh/via-macii: Simplify locking
351e5ad327d07 macintosh/via-macii, macintosh/adb-iop: Modernize printk calls
47fd2060660e6 macintosh/via-macii, macintosh/adb-iop: Clean up whitespace

Just for the sake of simplicity, the 'fixes' tags in this series limit
backporting to 'v5.0+'.

Finn Thain (9):
macintosh/via-macii: Access autopoll_devs when inside lock
macintosh/via-macii: Poll the device most likely to respond
macintosh/via-macii: Handle /CTLR_IRQ signal correctly
macintosh/via-macii: Remove read_done state
macintosh/via-macii: Handle poll replies correctly
macintosh/via-macii: Use bool type for reading_reply variable
macintosh/via-macii: Use unsigned type for autopoll_devs variable
macintosh/via-macii: Use the stack for reset request storage
macintosh/via-macii: Clarify definition of macii_init()

drivers/macintosh/via-macii.c | 324 +++++++++++++++++++---------------
1 file changed, 179 insertions(+), 145 deletions(-)

--
2.26.2