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List:       flashrom
Subject:    [flashrom] ft2232_spi JTAGkey OE disabled for CS high
From:       Ulrich Holeschak <ulrich () holeschak ! de>
Date:       2016-05-19 23:08:46
Message-ID: 67fb6e64-d285-2ef5-8535-c292daec5e73 () holeschak ! de
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Hello,
when using the ft2232_spi driver with Amontec JTAGkey, the OE signal 
(bit 4) is disabled
when de-asserting CS:
     msg_pspew("De-assert CS#\n");
     buf[i++] = SET_BITS_LOW;
     buf[i++] = cs_bits;
     buf[i++] = pindir;

This means that the CS high signal is floating and the voltage level is 
unstable.

Filtering the OE bit fixes this issue:
     msg_pspew("De-assert CS#\n");
     buf[i++] = SET_BITS_LOW;
     buf[i++] = cs_bits & 0x0F;    // keep OE active
     buf[i++] = pindir;

Regards,
Ulrich



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