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SubjectRe: [PATCH] spi: rockchip: return 0 if tx_buf and rx_buf are NULL
Hi Addy,

On Thu, Aug 14, 2014 at 08:52:24AM +0800, Addy Ke wrote:
> To do so, spi communication can use an empty buf to pull up CS.
>
> This patch merged from ChromiumOS tree.
> Cros_ec use this function to turn off CS and add a delay to ensure
> the rising edge doesn't come too soon after the end of the data.
>
> Tested-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
> ---
> drivers/spi/spi-rockchip.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index 72fb287..1e3bcfa 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -511,8 +511,8 @@ static int rockchip_spi_transfer_one(struct spi_master *master,
> WARN_ON((readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));
>
> if (!xfer->tx_buf && !xfer->rx_buf) {
> - dev_err(rs->dev, "No buffer for transfer\n");
> - return -EINVAL;
> + dev_dbg(rs->dev, "No buffer for transfer\n");
> + return 0;
> }

Maybe we should only return 0 if xfer->len is also 0, otherwise keep
complaining loudly?

if (!xfer->tx_buf && !xfer->rx_buf) {
if (xfer->len == 0)
return 0;

dev_err(rs->dev, "Missing transfer buffer\n");
return -EINVAL;
}

Thanks.

--
Dmitry


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