This is a discussion on Add a delay in wdc.c following IDENTIFY within the mailing.openbsd.tech forums, part of the OpenBSD category; --> OpenBSD 3.8 GENERIC will not recognize my Plextor PX-708A DVD recorder. In investigating this I discovered the cause is ...
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| OpenBSD 3.8 GENERIC will not recognize my Plextor PX-708A DVD recorder. In investigating this I discovered the cause is that the 708A will not accept multiple IDENTIFY_PACKET_DEVICE commands in rapid succession. Multiple IDENTIFYs shouldn't occur, but do because wdc_attach in sys/dev/ic/wdc.c does one IDENTIFY, and the subsequent atapiscsi.c module does another IDENTIFY on its attach rather than reading the existing IDENTIFY data already stored by wdc.c. By experiment, I determined that a 10ms delay in the wdc_attach routine after the first IDENTIFY solved the problem. I'm not an expert on the ATA/ATAPI spec - I believe that the problem is with the Plextor device, not the driver, but I've seen enough messages in a Google search to know this problem has occurred more than once with ATAPI devices and OpenBSD, and I'm wondering if the maintainer of the wdc.c code would consider adding such a delay (since there's already code in that routine for a delay after a reset). |
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