On Tue, Apr 5, 2022 at 1:33 PM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> From: Sean Young <sean@xxxxxxxx>
>
> commit 5ad05ecad4326ddaa26a83ba2233a67be24c1aaa upstream.
>
> Calling udelay for than 1000us does not always yield the correct
> results.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Михаил <vrserver1@xxxxxxxxx>
> Signed-off-by: Sean Young <sean@xxxxxxxx>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/media/rc/gpio-ir-tx.c | 28 +++++++++++++++++++++-------
> 1 file changed, 21 insertions(+), 7 deletions(-)
>
> --- a/drivers/media/rc/gpio-ir-tx.c
> +++ b/drivers/media/rc/gpio-ir-tx.c
> @@ -48,11 +48,29 @@ static int gpio_ir_tx_set_carrier(struct
> return 0;
> }
>
> +static void delay_until(ktime_t until)
> +{
> + /*
> + * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
> + * m68k ndelay(s64) does not compile; so use s32 rather than s64.
> + */
> + s32 delta;
> +
> + while (true) {
> + delta = ktime_us_delta(until, ktime_get());
> + if (delta <= 0)
> + return;
> +
> + /* udelay more than 1ms may not work */
> + delta = min(delta, 1000);
> + udelay(delta);
> + }
Yeah, that's why we have mdelay(), which loops around udelay() if no
arch-specific implementation is provided.
> +}
> +
> static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
> uint count)
> {
> ktime_t edge;
> - s32 delta;
> int i;
>
> local_irq_disable();
> @@ -63,9 +81,7 @@ static void gpio_ir_tx_unmodulated(struc
> gpiod_set_value(gpio_ir->gpio, !(i % 2));
>
> edge = ktime_add_us(edge, txbuf[i]);
> - delta = ktime_us_delta(edge, ktime_get());
> - if (delta > 0)
> - udelay(delta);
> + delay_until(edge);
> }
>
> gpiod_set_value(gpio_ir->gpio, 0);
> @@ -97,9 +113,7 @@ static void gpio_ir_tx_modulated(struct
> if (i % 2) {
> // space
> edge = ktime_add_us(edge, txbuf[i]);
> - delta = ktime_us_delta(edge, ktime_get());
> - if (delta > 0)
> - udelay(delta);
> + delay_until(edge);
> } else {
> // pulse
> ktime_t last = ktime_add_us(edge, txbuf[i]);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
