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>
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@ -789,6 +789,7 @@ static int spi_transfer_one_message(struct spi_master *master,
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list_for_each_entry(xfer, &msg->transfers, transfer_list) {
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trace_spi_transfer_start(msg, xfer);
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if (xfer->tx_buf || xfer->rx_buf) {
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reinit_completion(&master->xfer_completion);
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ret = master->transfer_one(master, msg->spi, xfer);
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@ -808,9 +809,16 @@ static int spi_transfer_one_message(struct spi_master *master,
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}
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if (ms == 0) {
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dev_err(&msg->spi->dev, "SPI transfer timed out\n");
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dev_err(&msg->spi->dev,
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"SPI transfer timed out\n");
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msg->status = -ETIMEDOUT;
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}
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} else {
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if (xfer->len)
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dev_err(&msg->spi->dev,
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"Bufferless transfer has length %u\n",
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xfer->len);
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}
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trace_spi_transfer_stop(msg, xfer);
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