On Thu, Sep 04, 2025 at 12:24:17AM +0200, Andrew Lunn wrote:
> > struct mucse_mbx_info {
> > + struct mucse_mbx_stats stats;
> > + u32 timeout;
> > + u32 usec_delay;
> > + u16 size;
> > + u16 fw_req;
> > + u16 fw_ack;
> > + /* lock for only one use mbx */
> > + struct mutex lock;
> > /* fw <--> pf mbx */
> > u32 fw_pf_shm_base;
> > u32 pf2fw_mbox_ctrl;
>
> > +/**
> > + * mucse_obtain_mbx_lock_pf - Obtain mailbox lock
> > + * @hw: pointer to the HW structure
> > + *
> > + * This function maybe used in an irq handler.
> > + *
> > + * Return: 0 if we obtained the mailbox lock or else -EIO
> > + **/
> > +static int mucse_obtain_mbx_lock_pf(struct mucse_hw *hw)
> > +{
> > + struct mucse_mbx_info *mbx = &hw->mbx;
> > + int try_cnt = 5000;
> > + u32 reg;
> > +
> > + reg = PF2FW_MBOX_CTRL(mbx);
> > + while (try_cnt-- > 0) {
> > + mbx_ctrl_wr32(mbx, reg, MBOX_PF_HOLD);
> > + /* force write back before check */
> > + wmb();
> > + if (mbx_ctrl_rd32(mbx, reg) & MBOX_PF_HOLD)
> > + return 0;
> > + udelay(100);
> > + }
> > + return -EIO;
> > +}
>
> If there is a function which obtains a lock, there is normally a
> function which releases a lock. But i don't see it.
>
The lock is relased when send MBOX_CTRL_REQ in mucse_write_mbx_pf:
mbx_ctrl_wr32(mbx, ctrl_reg, MBOX_CTRL_REQ);
Set MBOX_PF_HOLD(bit3) to hold the lock, clear bit3 to release, and set
MBOX_CTRL_REQ(bit0) to send the req. req and lock are different bits in
one register. So we send the req along with releasing lock (set bit0 and
clear bit3).
Maybe I should add comment like this?
/* send the req along with releasing the lock */
mbx_ctrl_wr32(mbx, ctrl_reg, MBOX_CTRL_REQ);
> > +void mucse_init_mbx_params_pf(struct mucse_hw *hw)
> > +{
> > + struct mucse_mbx_info *mbx = &hw->mbx;
> > +
> > + mbx->usec_delay = 100;
> > + mbx->timeout = (4 * USEC_PER_SEC) / mbx->usec_delay;
> > + mbx->stats.msgs_tx = 0;
> > + mbx->stats.msgs_rx = 0;
> > + mbx->stats.reqs = 0;
> > + mbx->stats.acks = 0;
> > + mbx->size = MUCSE_MAILBOX_BYTES;
> > + mutex_init(&mbx->lock);
>
> And this mutex never seems to be used anywhere. What is it supposed to
> be protecting?
>
mbx->lock is used in patch5, to ensure that only one uses mbx.
I will move it to patch5.
> Andrew
>
> ---
> pw-bot: cr
>
Thanks for your feedback.
