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SubjectRe: [PATCH 07/11] spi: Deal with slaves that return from transfer_one() unfinished
Hi Lubomir,

On Wed, Oct 10, 2018 at 7:10 PM Lubomir Rintel <lkundrak@v3.sk> wrote:
> Some drivers, such as spi-pxa2xx return from the transfer_one callback
> immediately, idicating that the transfer will be finished asynchronously.
>
> Normally, spi_transfer_one_message() synchronously waits for the
> transfer to finish with wait_for_completion_timeout(). For slaves, we
> don't want the transaction to time out as it can complete in a long time
> in future. Use wait_for_completion_interruptible() instead.
>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>

Thanks for your patch!

> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -993,6 +993,44 @@ static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
> return __spi_map_msg(ctlr, msg);
> }
>
> +static int spi_transfer_wait(struct spi_controller *ctlr,
> + struct spi_message *msg,
> + struct spi_transfer *xfer)
> +{
> + struct spi_statistics *statm = &ctlr->statistics;
> + struct spi_statistics *stats = &msg->spi->statistics;
> + unsigned long long ms = 1;
> +
> + if (spi_controller_is_slave(ctlr)) {
> + if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
> + dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
> + return -EINTR;

Why not setting msg->status = -EINTR here, but returning an error? ...

> + }
> + } else {
> + ms = 8LL * 1000LL * xfer->len;
> + do_div(ms, xfer->speed_hz);
> + ms += ms + 200; /* some tolerance */
> +
> + if (ms > UINT_MAX)
> + ms = UINT_MAX;
> +
> + ms = wait_for_completion_timeout(&ctlr->xfer_completion,
> + msecs_to_jiffies(ms));
> +
> + if (ms == 0) {
> + SPI_STATISTICS_INCREMENT_FIELD(statm,
> + timedout);
> + SPI_STATISTICS_INCREMENT_FIELD(stats,
> + timedout);
> + dev_err(&msg->spi->dev,
> + "SPI transfer timed out\n");
> + msg->status = -ETIMEDOUT;
> + }
> + }
> +
> + return 0;
> +}
> +
> /*
> * spi_transfer_one_message - Default implementation of transfer_one_message()
> *
> @@ -1006,7 +1044,6 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
> struct spi_transfer *xfer;
> bool keep_cs = false;
> int ret = 0;
> - unsigned long long ms = 1;
> struct spi_statistics *statm = &ctlr->statistics;
> struct spi_statistics *stats = &msg->spi->statistics;
>
> @@ -1035,28 +1072,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
> goto out;
> }
>
> - if (ret > 0) {
> - ret = 0;
> - ms = 8LL * 1000LL * xfer->len;
> - do_div(ms, xfer->speed_hz);
> - ms += ms + 200; /* some tolerance */
> -
> - if (ms > UINT_MAX)
> - ms = UINT_MAX;
> + if (ret > 0)
> + ret = spi_transfer_wait(ctlr, msg, xfer);
>
> - ms = wait_for_completion_timeout(&ctlr->xfer_completion,
> - msecs_to_jiffies(ms));
> - }
> -
> - if (ms == 0) {
> - SPI_STATISTICS_INCREMENT_FIELD(statm,
> - timedout);
> - SPI_STATISTICS_INCREMENT_FIELD(stats,
> - timedout);
> - dev_err(&msg->spi->dev,
> - "SPI transfer timed out\n");
> - msg->status = -ETIMEDOUT;
> - }
> + if (ret < 0)
> + return ret;

... which will return here, skipping all finalization and cleanup below?

> } else {
> if (xfer->len)
> dev_err(&msg->spi->dev,

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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