diff options
| author |   Mark Brown <broonie@linaro.org> | 2014-08-16 16:27:41 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@linaro.org> | 2014-08-19 16:08:58 -0500 |
| commit | 38ec10f60d9ca3a7eb3a5b52500a67479296b86f (patch) | |
| tree | 1e09865555d0c2dadf6d81445ad7f3f766058815 /drivers/spi/spi.c | |
| parent | Linux 3.17-rc1 (diff) | |
| download | linux-dev-38ec10f60d9ca3a7eb3a5b52500a67479296b86f.tar.xz linux-dev-38ec10f60d9ca3a7eb3a5b52500a67479296b86f.zip | |
spi: Only call transfer_one() if we have buffers to transfer
Client drivers such as the ChomeOS EC driver sometimes use transfers with
no buffers and only a delay specified in order to allow a delay after the
assertion of /CS. Rather than require controller drivers handle this noop
case gracefully put checks in the core to ensure that we don't call into
the controller for such transfers.
Reported-by: Addy Ke <addy.ke@rock-chips.com>
Tested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'drivers/spi/spi.c')
| -rw-r--r-- | drivers/spi/spi.c | 44 |
1 files changed, 26 insertions, 18 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index e0531baf2782..0edccc82ece5 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -789,27 +789,35 @@ static int spi_transfer_one_message(struct spi_master *master, list_for_each_entry(xfer, &msg->transfers, transfer_list) { trace_spi_transfer_start(msg, xfer); - reinit_completion(&master->xfer_completion); - - ret = master->transfer_one(master, msg->spi, xfer); - if (ret < 0) { - dev_err(&msg->spi->dev, - "SPI transfer failed: %d\n", ret); - goto out; - } + if (xfer->tx_buf || xfer->rx_buf) { + reinit_completion(&master->xfer_completion); + + ret = master->transfer_one(master, msg->spi, xfer); + if (ret < 0) { + dev_err(&msg->spi->dev, + "SPI transfer failed: %d\n", ret); + goto out; + } - if (ret > 0) { - ret = 0; - ms = xfer->len * 8 * 1000 / xfer->speed_hz; - ms += ms + 100; /* some tolerance */ + if (ret > 0) { + ret = 0; + ms = xfer->len * 8 * 1000 / xfer->speed_hz; + ms += ms + 100; /* some tolerance */ - ms = wait_for_completion_timeout(&master->xfer_completion, - msecs_to_jiffies(ms)); - } + ms = wait_for_completion_timeout(&master->xfer_completion, + msecs_to_jiffies(ms)); + } - if (ms == 0) { - dev_err(&msg->spi->dev, "SPI transfer timed out\n"); - msg->status = -ETIMEDOUT; + if (ms == 0) { + dev_err(&msg->spi->dev, + "SPI transfer timed out\n"); + msg->status = -ETIMEDOUT; + } + } else { + if (xfer->len) + dev_err(&msg->spi->dev, + "Bufferless transfer has length %u\n", + xfer->len); } trace_spi_transfer_stop(msg, xfer); |