On Tue, Apr 22, 2014 at 10:18:21PM +0100, Mark Brown wrote:
> From: Mark Brown <broonie@xxxxxxxxxx>
>
> While searching for users of spi_async() I found a reference in the ad7877
> driver to using it to initiate data transfer from the interrupt handler.
> However there is no code for this, instead the interrupt handler is a
> threaded handler and uses spi_sync() instead.
>
> Remove the bitrotted comment, though in actual fact the use case mentioned
> is a great use for spi_async() since it would cut down on latency handling
> the interrupt by saving us a context switch before we start SPI.
>
> This was previously implemented, it was removed in commit b534422b2d11
> (Input: ad7877 - switch to using threaded IRQ) for code complexity reasons.
> It may be better to revert that commit instead.
Hmm, maybe.. although I think original would cause device 'stuck' if
call to spi_async() fails, so probably not a straight revert...
>
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
> ---
> drivers/input/touchscreen/ad7877.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
> index 6793c85903ae..523865daa1d3 100644
> --- a/drivers/input/touchscreen/ad7877.c
> +++ b/drivers/input/touchscreen/ad7877.c
> @@ -210,11 +210,6 @@ static bool gpio3;
> module_param(gpio3, bool, 0);
> MODULE_PARM_DESC(gpio3, "If gpio3 is set to 1 AUX3 acts as GPIO3");
>
> -/*
> - * ad7877_read/write are only used for initial setup and for sysfs controls.
> - * The main traffic is done using spi_async() in the interrupt handler.
> - */
> -
> static int ad7877_read(struct spi_device *spi, u16 reg)
> {
> struct ser_req *req;
> --
> 1.9.2
>
>
--
Dmitry
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