[2/3] i2c:ocores: do not handle IRQ if IF is not set

Message ID 20180625161303.7991-3-federico.vaga@cern.ch
State Superseded
Headers show
Series
  • [1/3] i2c:ocores: stop transfer on timeout
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Commit Message

Federico Vaga June 25, 2018, 4:13 p.m.
If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
- the line can be shared with other devices
- it can be a spurious interrupt

To avoid reading twice the status register, the ocores_process() function
expects it to be read by the caller.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
---
 drivers/i2c/busses/i2c-ocores.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Peter Korsgaard Oct. 21, 2018, 2:12 p.m. | #1
On Mon, Jun 25, 2018 at 6:14 PM Federico Vaga <federico.vaga@cern.ch> wrote:
>
> If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
> - the line can be shared with other devices
> - it can be a spurious interrupt
>
> To avoid reading twice the status register, the ocores_process() function
> expects it to be read by the caller.
>
> Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

Looks good.

Acked-by: Peter Korsgaard <peter@korsgaard.com>
Wolfram Sang Oct. 29, 2018, 8:53 a.m. | #2
On Sun, Oct 21, 2018 at 04:12:10PM +0200, Peter Korsgaard wrote:
> On Mon, Jun 25, 2018 at 6:14 PM Federico Vaga <federico.vaga@cern.ch> wrote:
> >
> > If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
> > - the line can be shared with other devices
> > - it can be a spurious interrupt
> >
> > To avoid reading twice the status register, the ocores_process() function
> > expects it to be read by the caller.
> >
> > Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
> 
> Looks good.
> 
> Acked-by: Peter Korsgaard <peter@korsgaard.com>

I assume this patch will be resent when the other patches get updated?
Or shall I pick this one independently of the others?
Federico Vaga Oct. 29, 2018, 2:27 p.m. | #3
On Monday, October 29, 2018 9:53:01 AM CET Wolfram Sang wrote:
> On Sun, Oct 21, 2018 at 04:12:10PM +0200, Peter Korsgaard wrote:
> > On Mon, Jun 25, 2018 at 6:14 PM Federico Vaga <federico.vaga@cern.ch> 
wrote:
> > > If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
> > > - the line can be shared with other devices
> > > - it can be a spurious interrupt
> > > 
> > > To avoid reading twice the status register, the ocores_process()
> > > function
> > > expects it to be read by the caller.
> > > 
> > > Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
> > 
> > Looks good.
> > 
> > Acked-by: Peter Korsgaard <peter@korsgaard.com>
> 
> I assume this patch will be resent when the other patches get updated?
> Or shall I pick this one independently of the others?

Since Peter did not answer yet, I would say to wait because I'm going to re-
send the full patch-set soon.

Patch

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index 98c0ef74882b..274d6eb22a2c 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -139,10 +139,9 @@  static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
 	return i2c->getreg(i2c, reg);
 }
 
-static void ocores_process(struct ocores_i2c *i2c)
+static void ocores_process(struct ocores_i2c *i2c, u8 stat)
 {
 	struct i2c_msg *msg = i2c->msg;
-	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 
 	if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
 		/* stop has been sent */
@@ -209,9 +208,13 @@  static void ocores_process(struct ocores_i2c *i2c)
 static irqreturn_t ocores_isr(int irq, void *dev_id)
 {
 	struct ocores_i2c *i2c = dev_id;
+	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 	unsigned long flags;
 	int ret;
 
+	if (!(stat & OCI2C_STAT_IF))
+		return IRQ_NONE;
+
 	/*
 	 * We need to protect i2c against a timeout event (see ocores_xfer())
 	 * If we cannot take this lock, it means that we are already in
@@ -222,7 +225,7 @@  static irqreturn_t ocores_isr(int irq, void *dev_id)
 	if (!ret)
 		return IRQ_HANDLED;
 
-	ocores_process(i2c);
+	ocores_process(i2c, stat);
 
 	spin_unlock_irqrestore(&i2c->xfer_lock, flags);