2022-02-14 20:04:52

by Maciej W. Rozycki

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Subject: [PATCH v2 0/2] serial: 8250: Correct basic issues with the PCI blacklist

Hi,

This v2 of the patch series adds missing filler member initialisers for
blacklist entries using the PCI_DEVICE rather than PCI_VDEVICE macro that
cause "initializer element is not computable at load time" compilation
errors in some configurations, which have escaped my verification.

An upside is I have noticed PARPORT_SERIAL (or indeed PARPORT_PC) is not
selectable with numerous PCI platforms like RISC-V meaning that PC-style
PCI parallel port hardware cannot be used with them even though there's no
reason for that. The only PCI platforms that actually cannot make use of
such hardware are those newer PCIe systems that have no support for I/O
cycles in the host bridge with the only actual specimen known to me being
the POWER9 PHB4 device, so we ought to enable PARPORT_PC/PARPORT_SERIAL
support for PCI systems in the general case. I'll post a fix separately.

The original cover letter continues.

In the course of investigating whether support code for OxSemi PCIe UARTs
could be factored out from the common 8250 PCI UART driver, which has been
previously requested by Andy (cc-ed), I have noticed that the Kconfig help
text for several device-specific UART drivers previously factored out is
incorrect in that it claims that those dedicated drivers are required for
extra features of the respective devices, while actually the blacklist
entries within the common driver make them require those dedicated drivers
even for standard features, as the common driver now refuses to handle
them.

Also it may be unclear for the user from a specific PCI device ID of an
affected PCI UART device which dedicated driver has to be configured in to
handle it, so make the blacklist entries include that information to be
printed if a device is encountered that cannot be handled because its
dedicated driver has been excluded from configuration while the common
driver refuses to handle it.

See the respective change descriptions for further details. Please
apply.

Maciej