diff mbox series

[2/2] bus: sunxi-rsb: Support atomic transfers

Message ID 20221105191954.14360-3-samuel@sholland.org
State New
Headers
Series bus: sunxi-rsb: Fix poweroff issues |

Commit Message

Samuel Holland Nov. 5, 2022, 7:19 p.m. UTC 
  When communicating with a PMIC during system poweroff (pm_power_off()),
IRQs are disabled and we are in a RCU read-side critical section, so we
cannot use wait_for_completion_io_timeout(). Instead, poll the status
register for transfer completion.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---

 drivers/bus/sunxi-rsb.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

Comments

Jernej Škrabec Nov. 5, 2022, 7:46 p.m. UTC | #1 
Dne sobota, 05. november 2022 ob 20:19:53 CET je Samuel Holland napisal(a):
> When communicating with a PMIC during system poweroff (pm_power_off()),
> IRQs are disabled and we are in a RCU read-side critical section, so we
> cannot use wait_for_completion_io_timeout(). Instead, poll the status
> register for transfer completion.
> 
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
> 
>  drivers/bus/sunxi-rsb.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
> index 17343cd75338..0f0e498d4379 100644
> --- a/drivers/bus/sunxi-rsb.c
> +++ b/drivers/bus/sunxi-rsb.c
> @@ -267,6 +267,9 @@ EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
>  /* common code that starts a transfer */
>  static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>  {
> +	bool timeout;
> +	u32 status;
> +
>  	if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
>  		dev_dbg(rsb->dev, "RSB transfer still in progress\n");
>  		return -EBUSY;
> @@ -279,8 +282,16 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>  	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
>  	       rsb->regs + RSB_CTRL);
> 
> -	if (!wait_for_completion_io_timeout(&rsb->complete,
> -					    
msecs_to_jiffies(100))) {
> +	if (irqs_disabled()) {
> +		timeout = readl_poll_timeout_atomic(rsb->regs + 
RSB_INTS,
> +						    status, 
status, 10, 100000);

It would be good to check only for RSB_INTS_LOAD_BSY, RSB_INTS_TRANS_ERR and 
RSB_INTS_TRANS_OVER flags and clear them afterwards. That way we avoid problems 
if this path is used outside power off case.

Best regards,
Jernej

> +	} else {
> +		timeout = !wait_for_completion_io_timeout(&rsb-
>complete,
> +							  
msecs_to_jiffies(100));
> +		status = rsb->status;
> +	}
> +
> +	if (timeout) {
>  		dev_dbg(rsb->dev, "RSB timeout\n");
> 
>  		/* abort the transfer */
> @@ -292,18 +303,18 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>  		return -ETIMEDOUT;
>  	}
> 
> -	if (rsb->status & RSB_INTS_LOAD_BSY) {
> +	if (status & RSB_INTS_LOAD_BSY) {
>  		dev_dbg(rsb->dev, "RSB busy\n");
>  		return -EBUSY;
>  	}
> 
> -	if (rsb->status & RSB_INTS_TRANS_ERR) {
> -		if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
> +	if (status & RSB_INTS_TRANS_ERR) {
> +		if (status & RSB_INTS_TRANS_ERR_ACK) {
>  			dev_dbg(rsb->dev, "RSB slave nack\n");
>  			return -EINVAL;
>  		}
> 
> -		if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
> +		if (status & RSB_INTS_TRANS_ERR_DATA) {
>  			dev_dbg(rsb->dev, "RSB transfer data 
error\n");
>  			return -EIO;
>  		}
Jernej Škrabec Nov. 5, 2022, 7:48 p.m. UTC | #2 
Dne sobota, 05. november 2022 ob 20:46:47 CET je Jernej Škrabec napisal(a):
> Dne sobota, 05. november 2022 ob 20:19:53 CET je Samuel Holland napisal(a):
> > When communicating with a PMIC during system poweroff (pm_power_off()),
> > IRQs are disabled and we are in a RCU read-side critical section, so we
> > cannot use wait_for_completion_io_timeout(). Instead, poll the status
> > register for transfer completion.
> > 
> > Signed-off-by: Samuel Holland <samuel@sholland.org>

Also a fixes tag would be in order here.

Best regards,
Jernej

> > ---
> > 
> >  drivers/bus/sunxi-rsb.c | 23 +++++++++++++++++------
> >  1 file changed, 17 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
> > index 17343cd75338..0f0e498d4379 100644
> > --- a/drivers/bus/sunxi-rsb.c
> > +++ b/drivers/bus/sunxi-rsb.c
> > @@ -267,6 +267,9 @@ EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
> > 
> >  /* common code that starts a transfer */
> >  static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
> >  {
> > 
> > +	bool timeout;
> > +	u32 status;
> > +
> > 
> >  	if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
> >  	
> >  		dev_dbg(rsb->dev, "RSB transfer still in progress\n");
> >  		return -EBUSY;
> > 
> > @@ -279,8 +282,16 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
> > 
> >  	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
> >  	
> >  	       rsb->regs + RSB_CTRL);
> > 
> > -	if (!wait_for_completion_io_timeout(&rsb->complete,
> > -
> 
> msecs_to_jiffies(100))) {
> 
> > +	if (irqs_disabled()) {
> > +		timeout = readl_poll_timeout_atomic(rsb->regs +
> 
> RSB_INTS,
> 
> > +						    status,
> 
> status, 10, 100000);
> 
> It would be good to check only for RSB_INTS_LOAD_BSY, RSB_INTS_TRANS_ERR and
> RSB_INTS_TRANS_OVER flags and clear them afterwards. That way we avoid
> problems if this path is used outside power off case.
> 
> Best regards,
> Jernej
> 
> > +	} else {
> > +		timeout = !wait_for_completion_io_timeout(&rsb-
> >
> >complete,
> >
> > +
> 
> msecs_to_jiffies(100));
> 
> > +		status = rsb->status;
> > +	}
> > +
> > +	if (timeout) {
> > 
> >  		dev_dbg(rsb->dev, "RSB timeout\n");
> >  		
> >  		/* abort the transfer */
> > 
> > @@ -292,18 +303,18 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb
> > *rsb)
> > 
> >  		return -ETIMEDOUT;
> >  	
> >  	}
> > 
> > -	if (rsb->status & RSB_INTS_LOAD_BSY) {
> > +	if (status & RSB_INTS_LOAD_BSY) {
> > 
> >  		dev_dbg(rsb->dev, "RSB busy\n");
> >  		return -EBUSY;
> >  	
> >  	}
> > 
> > -	if (rsb->status & RSB_INTS_TRANS_ERR) {
> > -		if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
> > +	if (status & RSB_INTS_TRANS_ERR) {
> > +		if (status & RSB_INTS_TRANS_ERR_ACK) {
> > 
> >  			dev_dbg(rsb->dev, "RSB slave nack\n");
> >  			return -EINVAL;
> >  		
> >  		}
> > 
> > -		if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
> > +		if (status & RSB_INTS_TRANS_ERR_DATA) {
> > 
> >  			dev_dbg(rsb->dev, "RSB transfer data
> 
> error\n");
> 
> >  			return -EIO;
> >  		
> >  		}
diff mbox series

Patch

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index 17343cd75338..0f0e498d4379 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -267,6 +267,9 @@  EXPORT_SYMBOL_GPL(sunxi_rsb_driver_register);
 /* common code that starts a transfer */
 static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 {
+	bool timeout;
+	u32 status;
+
 	if (readl(rsb->regs + RSB_CTRL) & RSB_CTRL_START_TRANS) {
 		dev_dbg(rsb->dev, "RSB transfer still in progress\n");
 		return -EBUSY;
@@ -279,8 +282,16 @@  static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
 	       rsb->regs + RSB_CTRL);
 
-	if (!wait_for_completion_io_timeout(&rsb->complete,
-					    msecs_to_jiffies(100))) {
+	if (irqs_disabled()) {
+		timeout = readl_poll_timeout_atomic(rsb->regs + RSB_INTS,
+						    status, status, 10, 100000);
+	} else {
+		timeout = !wait_for_completion_io_timeout(&rsb->complete,
+							  msecs_to_jiffies(100));
+		status = rsb->status;
+	}
+
+	if (timeout) {
 		dev_dbg(rsb->dev, "RSB timeout\n");
 
 		/* abort the transfer */
@@ -292,18 +303,18 @@  static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 		return -ETIMEDOUT;
 	}
 
-	if (rsb->status & RSB_INTS_LOAD_BSY) {
+	if (status & RSB_INTS_LOAD_BSY) {
 		dev_dbg(rsb->dev, "RSB busy\n");
 		return -EBUSY;
 	}
 
-	if (rsb->status & RSB_INTS_TRANS_ERR) {
-		if (rsb->status & RSB_INTS_TRANS_ERR_ACK) {
+	if (status & RSB_INTS_TRANS_ERR) {
+		if (status & RSB_INTS_TRANS_ERR_ACK) {
 			dev_dbg(rsb->dev, "RSB slave nack\n");
 			return -EINVAL;
 		}
 
-		if (rsb->status & RSB_INTS_TRANS_ERR_DATA) {
+		if (status & RSB_INTS_TRANS_ERR_DATA) {
 			dev_dbg(rsb->dev, "RSB transfer data error\n");
 			return -EIO;
 		}