Re: [PATCH 09/14] media: rzg2l-cru: Split hw locking from buffers

[Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>]

On Mon, Mar 30, 2026 at 12:19:00PM +0100, Dan Scally wrote:
> Hi Jacopo
> 
> On 27/03/2026 17:10, Jacopo Mondi wrote:
> > From: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
> > 
> > Split the locking between a spinlock dedicated to protect the hardware
> > slots programming (hw_lock) and one lock (qlock) to protect the queue of
> > buffers submitted by userspace.
> > 
> > Do not rework the locking strategy yet but start simply by splitting the
> > locking in two.
> > 
> > Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
> > ---
> >   .../media/platform/renesas/rzg2l-cru/rzg2l-video.c | 32 +++++++++++++---------
> >   1 file changed, 19 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > index a79b17e146bf..9406a089ec9f 100644
> > --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > @@ -112,19 +112,21 @@ static void return_unused_buffers(struct rzg2l_cru_dev *cru,
> >   	struct rzg2l_cru_buffer *buf, *node;
> >   	unsigned int i;
> > -	guard(spinlock_irq)(&cru->qlock);
> > -
> > -	for (i = 0; i < cru->num_buf; i++) {
> > -		if (cru->queue_buf[i]) {
> > -			vb2_buffer_done(&cru->queue_buf[i]->vb2_buf,
> > -					state);
> > -			cru->queue_buf[i] = NULL;
> > +	scoped_guard(spinlock_irq, &cru->hw_lock) {
> > +		for (i = 0; i < cru->num_buf; i++) {
> > +			if (cru->queue_buf[i]) {
> > +				vb2_buffer_done(&cru->queue_buf[i]->vb2_buf,
> > +						state);
> > +				cru->queue_buf[i] = NULL;
> > +			}
> >   		}
> >   	}
> > -	list_for_each_entry_safe(buf, node, &cru->buf_list, list) {
> > -		vb2_buffer_done(&buf->vb.vb2_buf, state);
> > -		list_del(&buf->list);
> > +	scoped_guard(spinlock_irq, &cru->qlock) {
> > +		list_for_each_entry_safe(buf, node, &cru->buf_list, list) {
> > +			vb2_buffer_done(&buf->vb.vb2_buf, state);
> > +			list_del(&buf->list);
> > +		}
> >   	}
> >   }
> > @@ -198,12 +200,16 @@ static void rzg2l_cru_fill_hw_slot(struct rzg2l_cru_dev *cru, int slot)
> >   	struct rzg2l_cru_buffer *buf;
> >   	dma_addr_t phys_addr;
> > +	lockdep_assert_held(&cru->hw_lock);
> 
> I think this condition mightn't be true at the point of this commit; as far
> as I can see this function is called without hw_lock being held in
> rzg2l_cru_initialize_axi() until patch 12.

Agree.

Kind Regards,
Tommaso

> 
> > +
> >   	/* A already populated slot shall never be overwritten. */
> >   	if (WARN_ON(cru->queue_buf[slot]))
> >   		return;
> >   	dev_dbg(cru->dev, "Filling HW slot: %d\n", slot);
> > +	guard(spinlock)(&cru->qlock);
> > +
> >   	if (list_empty(&cru->buf_list)) {
> >   		cru->queue_buf[slot] = NULL;
> >   		phys_addr = cru->scratch_phys;
> > @@ -342,7 +348,7 @@ void rzg2l_cru_stop_image_processing(struct rzg2l_cru_dev *cru)
> >   	unsigned int retries = 0;
> >   	u32 icnms;
> > -	scoped_guard(spinlock_irq, &cru->qlock) {
> > +	scoped_guard(spinlock_irq, &cru->hw_lock) {
> >   		/* Disable and clear the interrupt */
> >   		cru->info->disable_interrupts(cru);
> >   	}
> > @@ -560,7 +566,7 @@ irqreturn_t rzg2l_cru_irq(int irq, void *data)
> >   	u32 amnmbs;
> >   	int slot;
> > -	guard(spinlock_irqsave)(&cru->qlock);
> > +	guard(spinlock_irqsave)(&cru->hw_lock);
> >   	irq_status = rzg2l_cru_read(cru, CRUnINTS);
> >   	if (!irq_status)
> > @@ -662,7 +668,7 @@ irqreturn_t rzg3e_cru_irq(int irq, void *data)
> >   	u32 irq_status;
> >   	int slot;
> > -	guard(spinlock)(&cru->qlock);
> > +	guard(spinlock)(&cru->hw_lock);
> >   	irq_status = rzg2l_cru_read(cru, CRUnINTS2);
> >   	if (!irq_status)
> > 
>