diff mbox series

[v17,2/6] soc: qcom: rpmh: Update dirty flag only when data changes

Message ID 1586703004-13674-3-git-send-email-mkshah@codeaurora.org (mailing list archive)
State New, archived
Headers show
Series Invoke rpmh_flush for non OSI targets | expand

Commit Message

Maulik Shah April 12, 2020, 2:50 p.m. UTC
Currently rpmh ctrlr dirty flag is set for all cases regardless of data
is really changed or not. Add changes to update dirty flag when data is
changed to newer values. Update dirty flag everytime when data in batch
cache is updated since rpmh_flush() may get invoked from any CPU instead
of only last CPU going to low power mode.

Also move dirty flag updates to happen from within cache_lock and remove
unnecessary INIT_LIST_HEAD() call and a default case from switch.

Fixes: 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")
Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
Reviewed-by: Srinivas Rao L <lsrao@codeaurora.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
---
 drivers/soc/qcom/rpmh.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

Comments

Stephen Boyd April 13, 2020, 9:17 p.m. UTC | #1
Quoting Maulik Shah (2020-04-12 07:50:00)
> Currently rpmh ctrlr dirty flag is set for all cases regardless of data
> is really changed or not. Add changes to update dirty flag when data is
> changed to newer values. Update dirty flag everytime when data in batch
> cache is updated since rpmh_flush() may get invoked from any CPU instead
> of only last CPU going to low power mode.
> 
> Also move dirty flag updates to happen from within cache_lock and remove
> unnecessary INIT_LIST_HEAD() call and a default case from switch.
> 
> Fixes: 600513dfeef3 ("drivers: qcom: rpmh: cache sleep/wake state requests")
> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
> Reviewed-by: Srinivas Rao L <lsrao@codeaurora.org>
> Reviewed-by: Evan Green <evgreen@chromium.org>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Stephen Boyd April 16, 2020, 11:58 p.m. UTC | #2
Quoting Maulik Shah (2020-04-12 07:50:00)
> diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
> index eb0ded0..03630ae 100644
> --- a/drivers/soc/qcom/rpmh.c
> +++ b/drivers/soc/qcom/rpmh.c
> @@ -133,26 +134,27 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
>  
>         req->addr = cmd->addr;
>         req->sleep_val = req->wake_val = UINT_MAX;
> -       INIT_LIST_HEAD(&req->list);
>         list_add_tail(&req->list, &ctrlr->cache);
>  
>  existing:
> +       old_sleep_val = req->sleep_val;
> +       old_wake_val = req->wake_val;
> +
>         switch (state) {
>         case RPMH_ACTIVE_ONLY_STATE:
> -               if (req->sleep_val != UINT_MAX)
> -                       req->wake_val = cmd->data;
> -               break;
>         case RPMH_WAKE_ONLY_STATE:
>                 req->wake_val = cmd->data;
>                 break;
>         case RPMH_SLEEP_STATE:
>                 req->sleep_val = cmd->data;
>                 break;
> -       default:
> -               break;
>         }
>  
> -       ctrlr->dirty = true;
> +       ctrlr->dirty = (req->sleep_val != old_sleep_val ||
> +                       req->wake_val != old_wake_val) &&
> +                       req->sleep_val != UINT_MAX &&
> +                       req->wake_val != UINT_MAX;

Can this change ctrl->dirty from true to false? I'm worried that we need
to make this a saturating assignment instead of an assignment.

	ctrl->dirty = ctrl->dirty || (req->sleep_val != .. );

> +
>  unlock:
>         spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
>
Doug Anderson April 17, 2020, 9:16 p.m. UTC | #3
On Thu, Apr 16, 2020 at 4:59 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Maulik Shah (2020-04-12 07:50:00)
> > diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
> > index eb0ded0..03630ae 100644
> > --- a/drivers/soc/qcom/rpmh.c
> > +++ b/drivers/soc/qcom/rpmh.c
> > @@ -133,26 +134,27 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
> >
> >         req->addr = cmd->addr;
> >         req->sleep_val = req->wake_val = UINT_MAX;
> > -       INIT_LIST_HEAD(&req->list);
> >         list_add_tail(&req->list, &ctrlr->cache);
> >
> >  existing:
> > +       old_sleep_val = req->sleep_val;
> > +       old_wake_val = req->wake_val;
> > +
> >         switch (state) {
> >         case RPMH_ACTIVE_ONLY_STATE:
> > -               if (req->sleep_val != UINT_MAX)
> > -                       req->wake_val = cmd->data;
> > -               break;
> >         case RPMH_WAKE_ONLY_STATE:
> >                 req->wake_val = cmd->data;
> >                 break;
> >         case RPMH_SLEEP_STATE:
> >                 req->sleep_val = cmd->data;
> >                 break;
> > -       default:
> > -               break;
> >         }
> >
> > -       ctrlr->dirty = true;
> > +       ctrlr->dirty = (req->sleep_val != old_sleep_val ||
> > +                       req->wake_val != old_wake_val) &&
> > +                       req->sleep_val != UINT_MAX &&
> > +                       req->wake_val != UINT_MAX;
>
> Can this change ctrl->dirty from true to false? I'm worried that we need
> to make this a saturating assignment instead of an assignment.
>
>         ctrl->dirty = ctrl->dirty || (req->sleep_val != .. );

This seems like a serious problem with the current code and feels like
we need a fix sooner rather than later.  I'm sorry I missed it in
review (and in fact, I probably suggested the exact code that's here
so it's even more my fault).  :(

I posted:

https://lore.kernel.org/r/20200417141531.1.Ia4b74158497213eabad7c3d474c50bfccb3f342e@changeid

-Doug
diff mbox series

Patch

diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
index eb0ded0..03630ae 100644
--- a/drivers/soc/qcom/rpmh.c
+++ b/drivers/soc/qcom/rpmh.c
@@ -119,6 +119,7 @@  static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
 {
 	struct cache_req *req;
 	unsigned long flags;
+	u32 old_sleep_val, old_wake_val;
 
 	spin_lock_irqsave(&ctrlr->cache_lock, flags);
 	req = __find_req(ctrlr, cmd->addr);
@@ -133,26 +134,27 @@  static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
 
 	req->addr = cmd->addr;
 	req->sleep_val = req->wake_val = UINT_MAX;
-	INIT_LIST_HEAD(&req->list);
 	list_add_tail(&req->list, &ctrlr->cache);
 
 existing:
+	old_sleep_val = req->sleep_val;
+	old_wake_val = req->wake_val;
+
 	switch (state) {
 	case RPMH_ACTIVE_ONLY_STATE:
-		if (req->sleep_val != UINT_MAX)
-			req->wake_val = cmd->data;
-		break;
 	case RPMH_WAKE_ONLY_STATE:
 		req->wake_val = cmd->data;
 		break;
 	case RPMH_SLEEP_STATE:
 		req->sleep_val = cmd->data;
 		break;
-	default:
-		break;
 	}
 
-	ctrlr->dirty = true;
+	ctrlr->dirty = (req->sleep_val != old_sleep_val ||
+			req->wake_val != old_wake_val) &&
+			req->sleep_val != UINT_MAX &&
+			req->wake_val != UINT_MAX;
+
 unlock:
 	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 
@@ -287,6 +289,7 @@  static void cache_batch(struct rpmh_ctrlr *ctrlr, struct batch_cache_req *req)
 
 	spin_lock_irqsave(&ctrlr->cache_lock, flags);
 	list_add_tail(&req->list, &ctrlr->batch_cache);
+	ctrlr->dirty = true;
 	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 }
 
@@ -323,6 +326,7 @@  static void invalidate_batch(struct rpmh_ctrlr *ctrlr)
 	list_for_each_entry_safe(req, tmp, &ctrlr->batch_cache, list)
 		kfree(req);
 	INIT_LIST_HEAD(&ctrlr->batch_cache);
+	ctrlr->dirty = true;
 	spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
 }
 
@@ -507,7 +511,6 @@  int rpmh_invalidate(const struct device *dev)
 	int ret;
 
 	invalidate_batch(ctrlr);
-	ctrlr->dirty = true;
 
 	do {
 		ret = rpmh_rsc_invalidate(ctrlr_to_drv(ctrlr));