On 21-08-10 15:02:28, Jeaho Hwang wrote:
> hw_ep_prime sometimes fails if irq occurs while it rus on RT kernel.
> to prevent local_irq_save should keep the function from irqs.
>
> I am not sure where is the best to submit this patch, between RT and USB
> community so sending to both. thanks.
Greg, do you have any suggestions about it, the RT kernel schedules the interrupt
handler (top-half) out which causes the USB hardware atomic sequences are broken,
these hardware operations needs to be executed within limited time.
Peter
>
> Signed-off-by: Jeaho Hwang <jhhwang@xxxxxxxxxx>
> ---
> drivers/usb/chipidea/udc.c | 31 +++++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 5f35cdd2cf1d..a90498f17cc4 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -102,6 +102,9 @@ static int hw_ep_flush(struct ci_hdrc *ci, int num, int dir)
> {
> int n = hw_ep_bit(num, dir);
>
> + /* From zynq-7000 TRM, It can take a long time
> + * so irq disable is not a good option for RT
> + */
> do {
> /* flush any pending transfer */
> hw_write(ci, OP_ENDPTFLUSH, ~0, BIT(n));
> @@ -190,22 +193,32 @@ static int hw_ep_get_halt(struct ci_hdrc *ci, int num, int dir)
> static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
> {
> int n = hw_ep_bit(num, dir);
> + unsigned long flags;
> + int ret = 0;
>
> /* Synchronize before ep prime */
> wmb();
>
> - if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
> - return -EAGAIN;
> + /* irq affects this routine so irq should be disabled on RT.
> + * on standard kernel, irq is already disabled by callers.
> + */
> + local_irq_save(flags);
> + if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num))) {
> + ret = -EAGAIN;
> + goto out;
> + }
>
> hw_write(ci, OP_ENDPTPRIME, ~0, BIT(n));
>
> while (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
> cpu_relax();
> if (is_ctrl && dir == RX && hw_read(ci, OP_ENDPTSETUPSTAT, BIT(num)))
> - return -EAGAIN;
> + ret = -EAGAIN;
>
> +out:
> + local_irq_restore(flags);
> /* status shoult be tested according with manual but it doesn't work */
> - return 0;
> + return ret;
> }
>
> /**
> --
> 2.25.1
>
--
Thanks,
Peter Chen
