The patch titled spi: spi_write_then_read() bugfixes has been added to the -mm tree. Its filename is spi-spi_write_then_read-bugfixes.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: spi: spi_write_then_read() bugfixes From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> The "simplify spi_write_then_read()" patch included two regressions from the 2.6.27 behaviors: - The data it wrote out during the (full duplex) read side of the transfer was not zeroed. - It fails completely on half duplex hardware, such as Microwire and most "3-wire" SPI variants. So, revert that patch. A revised version should be submitted at some point, which can get the speedup on standard hardware (full duplex) without breaking on less-capable half-duplex stuff. Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> [2.6.28.x, 2.6.29.x] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/spi.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff -puN drivers/spi/spi.c~spi-spi_write_then_read-bugfixes drivers/spi/spi.c --- a/drivers/spi/spi.c~spi-spi_write_then_read-bugfixes +++ a/drivers/spi/spi.c @@ -658,7 +658,7 @@ int spi_write_then_read(struct spi_devic int status; struct spi_message message; - struct spi_transfer x; + struct spi_transfer x[2]; u8 *local_buf; /* Use preallocated DMA-safe buffer. We can't avoid copying here, @@ -669,9 +669,15 @@ int spi_write_then_read(struct spi_devic return -EINVAL; spi_message_init(&message); - memset(&x, 0, sizeof x); - x.len = n_tx + n_rx; - spi_message_add_tail(&x, &message); + memset(x, 0, sizeof x); + if (n_tx) { + x[0].len = n_tx; + spi_message_add_tail(&x[0], &message); + } + if (n_rx) { + x[1].len = n_rx; + spi_message_add_tail(&x[1], &message); + } /* ... unless someone else is using the pre-allocated buffer */ if (!mutex_trylock(&lock)) { @@ -682,15 +688,15 @@ int spi_write_then_read(struct spi_devic local_buf = buf; memcpy(local_buf, txbuf, n_tx); - x.tx_buf = local_buf; - x.rx_buf = local_buf; + x[0].tx_buf = local_buf; + x[1].rx_buf = local_buf + n_tx; /* do the i/o */ status = spi_sync(spi, &message); if (status == 0) - memcpy(rxbuf, x.rx_buf + n_tx, n_rx); + memcpy(rxbuf, x[1].rx_buf, n_rx); - if (x.tx_buf == buf) + if (x[0].tx_buf == buf) mutex_unlock(&lock); else kfree(local_buf); _ Patches currently in -mm which might be from dbrownell@xxxxxxxxxxxxxxxxxxxxx are origin.patch linux-next.patch spi-spi_write_then_read-bugfixes.patch rtc-rtc-ds1307-add-ds3231.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html