Messages in this thread | | | Date | Sun, 21 Dec 2008 15:46:10 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [patch 2.6.28-rc9] spi: spi_write_then_read() regression fix |
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On Sat, 20 Dec 2008, David Brownell wrote: > > All SPI transfers are full duplex, and are packaged as half duplex > by either discarding the data that's read ("write only"), or else > by writing zeroes ("read only"). That patch wasn't ensuring that > zeroes were getting written out during the "half duplex read" part > of the transaction; instead, old RX bits were getting sent.
Hmm. In addition, isn't this broken (in that same function):
memcpy(local_buf, txbuf, n_tx); x.tx_buf = local_buf; x.rx_buf = local_buf;
/* do the i/o */ status = spi_sync(spi, &message); if (status == 0) memcpy(rxbuf, x.rx_buf + n_tx, n_rx);
shouldn't that 'rx_buf' setup be
x.rx_buf = local_buf + n_tx;
since the whole point was that we allocated a buffer that can hold _both_ the rx and tx parts? Especially as that final copy into the resulting "rxbuf" thing uses that "+ n_tx" addition?
Linus
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