Date: Thu, 26 Oct 1995 13:42:45 +0100 From: se@zpr.uni-koeln.de (Stefan Esser) To: David Greenman <davidg@freefall.freebsd.org> Cc: CVS-commiters@freefall.freebsd.org, cvs-sys@freefall.freebsd.org, matt@lkg.dec.com Subject: Re: cvs commit: src/sys/pci if_de.c Message-ID: <199510261242.AA24313@Sysiphos> In-Reply-To: David Greenman <davidg@freefall.freebsd.org> "cvs commit: src/sys/pci if_de.c" (Oct 26, 0:40)
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On Oct 26, 0:40, David Greenman wrote: } Subject: cvs commit: src/sys/pci if_de.c } davidg 95/10/26 00:40:16 } } Modified: sys/pci if_de.c } Log: } From Matt Thomas: } } "I screwed the initialization of the burstsize. Right now it will default } to 0 (which can cause corruption problems on high latency PCI buses). It } should be set to 8 longwords to avoid problems with certain PCI chipsets." } } Submitted by: Matt Thomas <matt@lkg.dec.com> There is a global variable for the purpose of determining the maximum burst length. It is currently initialized to 4 longwords, but I guess having it default to 8 would be Ok. (We reduced it to 4 because of a problem reported by Matt Thomas with an old Saturn chip set revision). This variable is supposed to be used by all drivers that support burst transfers. It can be adjusted from the PCI host bridge probe code, if necessary or advantegous. Quoting from /sys/pci/pci.c: /*======================================================== ** ** Variables ** **======================================================== */ /* ** log2 of safe burst len (in words) */ unsigned pci_max_burst_len = 2; /* 2=16Byte, 3=32Byte, 4=64Byte, ... */ I'd really prefer if this mechanism was used ... (I intend to clean up the PCI and NCR code later this year. This will lead to significant simplifications, and I'd like to share as much code as possible with the new EISA and possibly PCMCIA code ...) Regards, STefan -- Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 ============================================================================== http://www.zpr.uni-koeln.de/~se <se@ZPR.Uni-Koeln.DE>
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