[PATCH v17 4/8] drm: bridge: Cadence: Add MHDP8501 DP/HDMI driver

[Dmitry Baryshkov]

On Tue, Sep 24, 2024 at 12:16:27PM GMT, Maxime Ripard wrote:
> On Tue, Sep 24, 2024 at 03:36:49PM GMT, Sandor Yu wrote:
> > +static int cdns_mhdp8501_read_hpd(struct cdns_mhdp8501_device *mhdp)
> > +{
> > +	u8 status;
> > +	int ret;
> > +
> > +	mutex_lock(&mhdp_mailbox_mutex);
> > +
> > +	ret = cdns_mhdp_mailbox_send(&mhdp->base, MB_MODULE_ID_GENERAL,
> > +				     GENERAL_GET_HPD_STATE, 0, NULL);
> > +	if (ret)
> > +		goto err_get_hpd;
> > +
> > +	ret = cdns_mhdp_mailbox_recv_header(&mhdp->base, MB_MODULE_ID_GENERAL,
> > +					    GENERAL_GET_HPD_STATE,
> > +					    sizeof(status));
> > +	if (ret)
> > +		goto err_get_hpd;
> > +
> > +	ret = cdns_mhdp_mailbox_recv_data(&mhdp->base, &status, sizeof(status));
> > +	if (ret)
> > +		goto err_get_hpd;
> > +
> > +	mutex_unlock(&mhdp_mailbox_mutex);
> 
> That's better I guess, but it's still not a good API design. If you
> can't have concurrent accesses, then cdns_mhdp_mailbox_send et al.
> should take the mutex themselves.

I think that a proper API might be:

int cdns_mhdp_mailbox_send_recv(struct cdns_mhdp_device *mhdp,
			u8 module_id, u8 opcode,
			u16 size, const u8 *message,
			u16 buf_size, u8 *buf);

Internally it should take the lock, exchange the data, then return.

-- 
With best wishes
Dmitry