Date: Tue, 5 Aug 1997 09:47:27 -0500 (CDT) From: dave adkins <adkin003@gold.tc.umn.edu> To: current@FreeBSD.ORG Subject: ide_pci, Tyan S1563S, and busmastering dma Message-ID: <Pine.NEB.3.96.970805085022.436A-100000@samthedog.gold.tc.umn.edu>
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Two things prevented the my Tyan S1562D from starting up in busmastering mode with FastDMA. 1) The conditional in generic_dmainit (ide_pci.c) was two restrictive to allow the Seagate CFA2161A to be recognized as DMA capable. 2) The Award bios (v4.01) does not enable FastDMA. When generic_dmainit is changed to allow PIO mode 3 drives and piix3 configuration is added to ide_pci_attach to enable enable FastDMA, the drive functions fine, and interrupt overhead as seen in sysctl -vm is about as low as for my NCR pci scsi. I also verified that the drive was, infact, using DMA by inserting counter in wdstart where wdd_dmastart kicks off the DMA. The counter shows usage for each of the configured drives. I assume that if I get no messages from the driver, the setup modes for the piix3 and the drives remain unchanged. What are the chances that the code could be changed to have configuration options to 1) relax the drive mode restrictions, and 2) force FastDMA? For now I just apply my own patch when I update my sources. The wd driver with FastDMA enabled has been working well for the past couple of days (since the SMP fix). dave adkins adkin003@gold.tc.umn.edu
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