Re: [PATCH] ath10k: Wait until copy complete is actually done before completing

pillair
2020-06-12T14:25:45Z

Hi Doug,

The send callback for the CEs do check for hw_index/SRRI before trying
to free the buffer.
But adding a check for copy-complete (before calling the individual CE
callbacks) seems to be the better approach. Hence I agree that this
patch should be added.

Thanks,
Rakesh Pillai.

On 2020-06-09 20:50, Douglas Anderson wrote:
> On wcn3990 we have "per_ce_irq = true". That makes the
> ath10k_ce_interrupt_summary() function always return 0xfff. The
> ath10k_ce_per_engine_service_any() function will see this and think
> that _all_ copy engines have an interrupt. Without checking, the
> ath10k_ce_per_engine_service() assumes that if it's called that the
> "copy complete" (cc) interrupt fired. This combination seems bad.
>
> Let's add a check to make sure that the "copy complete" interrupt
> actually fired in ath10k_ce_per_engine_service().
>
> This might fix a hard-to-reproduce failure where it appears that the
> copy complete handlers run before the copy is really complete.
> Specifically a symptom was that we were seeing this on a Qualcomm
> sc7180 board:
> arm-smmu 15000000.iommu: Unhandled context fault:
> fsr=0x402, iova=0x7fdd45780, fsynr=0x30003, cbfrsynra=0xc1, cb=10
>
> Even on platforms that don't have wcn3990 this still seems like it
> would be a sane thing to do. Specifically the current IRQ handler
> comments indicate that there might be other misc interrupt sources
> firing that need to be cleared. If one of those sources was the one
> that caused the IRQ handler to be called it would also be important to
> double-check that the interrupt we cared about actually fired.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Rakesh Pillai <pillair@codeaurora.org>

> ---
>
> drivers/net/wireless/ath/ath10k/ce.c | 30 +++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/ce.c
> b/drivers/net/wireless/ath/ath10k/ce.c
> index 294fbc1e89ab..ffdd4b995f33 100644
> --- a/drivers/net/wireless/ath/ath10k/ce.c
> +++ b/drivers/net/wireless/ath/ath10k/ce.c
> @@ -481,6 +481,15 @@ static inline void
> ath10k_ce_engine_int_status_clear(struct ath10k *ar,
> ath10k_ce_write32(ar, ce_ctrl_addr + wm_regs->addr, mask);
> }
>
> +static inline bool ath10k_ce_engine_int_status_check(struct ath10k
> *ar,
> + u32 ce_ctrl_addr,
> + unsigned int mask)
> +{
> + struct ath10k_hw_ce_host_wm_regs *wm_regs = ar->hw_ce_regs->wm_regs;
> +
> + return ath10k_ce_read32(ar, ce_ctrl_addr + wm_regs->addr) & mask;
> +}
> +
> /*
> * Guts of ath10k_ce_send.
> * The caller takes responsibility for any needed locking.
> @@ -1301,19 +1310,22 @@ void ath10k_ce_per_engine_service(struct
> ath10k *ar, unsigned int ce_id)
>
> spin_lock_bh(&ce->ce_lock);
>
> - /* Clear the copy-complete interrupts that will be handled here. */
> - ath10k_ce_engine_int_status_clear(ar, ctrl_addr,
> - wm_regs->cc_mask);
> + if (ath10k_ce_engine_int_status_check(ar, ctrl_addr,
> + wm_regs->cc_mask)) {
> + /* Clear before handling */
> + ath10k_ce_engine_int_status_clear(ar, ctrl_addr,
> + wm_regs->cc_mask);
>
> - spin_unlock_bh(&ce->ce_lock);
> + spin_unlock_bh(&ce->ce_lock);
>
> - if (ce_state->recv_cb)
> - ce_state->recv_cb(ce_state);
> + if (ce_state->recv_cb)
> + ce_state->recv_cb(ce_state);
>
> - if (ce_state->send_cb)
> - ce_state->send_cb(ce_state);
> + if (ce_state->send_cb)
> + ce_state->send_cb(ce_state);
>
> - spin_lock_bh(&ce->ce_lock);
> + spin_lock_bh(&ce->ce_lock);
> + }
>
> /*
> * Misc CE interrupts are not being handled, but still need