Date: Fri, 7 May 1999 09:40:57 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Julian Elischer <julian@whistle.com> Cc: hackers@freebsd.org Subject: Re: Slight suggested change to PCI config stuff. Message-ID: <Pine.BSF.4.05.9905070938490.411-100000@herring.nlsystems.com> In-Reply-To: <3732725E.2781E494@whistle.com>
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On Thu, 6 May 1999, Julian Elischer wrote: > The PCI probe routines for chipset_probe() are called while the PCI > code is traversing the linker set of loaded drivers. However it will > catch any 'generic' bridge devices. Thus if the user has linked in > a specific driver for a particular bridge device, it may not be > called as the generic code may get there first. I propose to change > the several places that traverse the linker set so that the > 'chipset' default code is either skipped and called last, or, not > put in the linker set, but rather called directly after the linker > set has failed to find the correct driver. I want to do this so that > I may load a specific driver to handle some of the features that > are not normally set up in some of these chipsets, and that the > generic code doesn't know about, due to their 'local' nature. > > For example, some of the Bridge chips have such things as > GPIO pins that can be controlled from the control registers > of the chipset. Obviously only a platform specific > driver can know what those IO pins are attached to (e.g. power > sensing. or an I2C bus.) > These pins are changed by doing PCI config-space writes to the > chipset, so should be controlled by that driver. Allowing a more > specific driver to over-ride the generic default driver would > seem to be the clean way to do this.. > > > Any comments? (this is in 3.x but I presume the same makes sense > in 4.x) This makes sense for 3.x. Everything is different for 4.x though post new-bus. The right think in 4.x is to use priority ordered probes (which I have working but haven't committed). If a driver matches the generic class it would return a lower priority than a driver which matches the device exactly. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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