Re: [PATCH v2] usb: mtu3: wait for TX FIFO to drain before disconnect

["Carlo Caione" <ccaione@baylibre.com>]

On Sat Jul 18, 2026 at 10:17 PM CEST, Marek Vasut wrote:
> On 7/18/26 12:37 PM, Carlo Caione wrote:
>
> [...]
>
>> +static int mtu3_wait_for_tx_fifo_empty(struct mtu3 *mtu)
>> +{
>> +	struct mtu3_ep *mep;
>> +	u32 value;
>> +	int ret = 0;
>> +	int i;
>> +
>> +	for (i = 1; i < mtu->num_eps; i++) {
>> +		mep = mtu->in_eps + i;
>> +		if (!(mep->flags & MTU3_EP_ENABLED) ||
>> +		    !list_empty(&mep->req_list))
>> +			continue;
>> +
>> +		if (readl_poll_timeout(mtu->mac_base + MU3D_EP_TXCR0(i),
>> +				       value, value & TX_FIFOEMPTY,
>> +				       MTU3_TX_FIFO_DRAIN_TIMEOUT_US)) {
>> +			dev_warn(mtu->dev, "%s TX FIFO did not drain\n",
>> +				 mep->name);
>> +			mtu3_ep_reset(mep);
>> +			ret = -ETIMEDOUT;
>
> You could get the ETIMEDOUT return value from readl_poll_timeout().

fair enough.

>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>>   /* set/clear the stall and toggle bits for non-ep0 */
>>   void mtu3_ep_stall_set(struct mtu3_ep *mep, bool set)
>>   {
>> @@ -261,8 +290,14 @@ void mtu3_ep_stall_set(struct mtu3_ep *mep, bool set)
>>   		set ? "SEND STALL" : "CLEAR STALL, with EP RESET");
>>   }
>>   
>> -void mtu3_dev_on_off(struct mtu3 *mtu, int is_on)
>> +int mtu3_dev_on_off(struct mtu3 *mtu, int is_on)
>>   {
>> +	int ret = 0;
>> +
>> +	/* QMU completion may precede transmission from the TX FIFO. */
>> +	if (!is_on)
>> +		ret = mtu3_wait_for_tx_fifo_empty(mtu);
>
> Shouldn't this bail early on ret != 0 ?

No, disconnect must still be forced after resetting a timed-out endpoint
(we still want to disconnect it, even forcefully)

cheers,

--
Carlo Caione