diff mbox series

[net-next,v6,02/25] net: dsa: qca8k: use iopoll macro for qca8k_busy_wait

Message ID 20210514210015.18142-3-ansuelsmth@gmail.com (mailing list archive)
State Accepted
Commit 2ad255f2faaffb3af786031fba2e7955454b558a
Delegated to: Netdev Maintainers
Headers show
Series Multiple improvement to qca8k stability | expand

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netdev/checkpatch warning WARNING: line length of 82 exceeds 80 columns
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Commit Message

Christian Marangi May 14, 2021, 8:59 p.m. UTC 
Use iopoll macro instead of while loop.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/dsa/qca8k.c | 23 +++++++++++------------
 drivers/net/dsa/qca8k.h |  2 ++
 2 files changed, 13 insertions(+), 12 deletions(-)

Comments

Russell King (Oracle) May 14, 2021, 10:52 p.m. UTC | #1 
On Fri, May 14, 2021 at 10:59:52PM +0200, Ansuel Smith wrote:
> Use iopoll macro instead of while loop.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>

This doesn't look quite right to me.

>  static int
>  qca8k_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
>  {
> -	unsigned long timeout;
> -
> -	timeout = jiffies + msecs_to_jiffies(20);
> +	u32 val;

val is unsigned here.

> +	/* Check if qca8k_read has failed for a different reason
> +	 * before returning -ETIMEDOUT
> +	 */
> +	if (ret < 0 && val < 0)

but here you are checking it for a negative number - this will always be
false, making the conditional code unreachable. Either the test is wrong,
or the type of val is wrong. Please resolve.
Christian Marangi May 14, 2021, 11:07 p.m. UTC | #2 
On Fri, May 14, 2021 at 11:52:25PM +0100, Russell King (Oracle) wrote:
> On Fri, May 14, 2021 at 10:59:52PM +0200, Ansuel Smith wrote:
> > Use iopoll macro instead of while loop.
> > 
> > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> > Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> 
> This doesn't look quite right to me.
> 
> >  static int
> >  qca8k_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
> >  {
> > -	unsigned long timeout;
> > -
> > -	timeout = jiffies + msecs_to_jiffies(20);
> > +	u32 val;
> 
> val is unsigned here.
> 
> > +	/* Check if qca8k_read has failed for a different reason
> > +	 * before returning -ETIMEDOUT
> > +	 */
> > +	if (ret < 0 && val < 0)
> 
> but here you are checking it for a negative number - this will always be
> false, making the conditional code unreachable. Either the test is wrong,
> or the type of val is wrong. Please resolve.
>

I know this is wrong and I will fix.
Anyway I tested this and I checked if with u32 a negative value was
actually provided and to my surprise the value was correctly returned.
Any idea why?

> -- 
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
diff mbox series

Patch

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 0b295da6c356..25fa7084e820 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -262,21 +262,20 @@  static struct regmap_config qca8k_regmap_config = {
 static int
 qca8k_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
 {
-	unsigned long timeout;
-
-	timeout = jiffies + msecs_to_jiffies(20);
+	u32 val;
+	int ret;
 
-	/* loop until the busy flag has cleared */
-	do {
-		u32 val = qca8k_read(priv, reg);
-		int busy = val & mask;
+	ret = read_poll_timeout(qca8k_read, val, !(val & mask),
+				0, QCA8K_BUSY_WAIT_TIMEOUT * USEC_PER_MSEC, false,
+				priv, reg);
 
-		if (!busy)
-			break;
-		cond_resched();
-	} while (!time_after_eq(jiffies, timeout));
+	/* Check if qca8k_read has failed for a different reason
+	 * before returning -ETIMEDOUT
+	 */
+	if (ret < 0 && val < 0)
+		return val;
 
-	return time_after_eq(jiffies, timeout);
+	return ret;
 }
 
 static void
diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
index 7ca4b93e0bb5..86c585b7ec4a 100644
--- a/drivers/net/dsa/qca8k.h
+++ b/drivers/net/dsa/qca8k.h
@@ -18,6 +18,8 @@ 
 #define PHY_ID_QCA8337					0x004dd036
 #define QCA8K_ID_QCA8337				0x13
 
+#define QCA8K_BUSY_WAIT_TIMEOUT				20
+
 #define QCA8K_NUM_FDB_RECORDS				2048
 
 #define QCA8K_CPU_PORT					0