2019-09-20 19:22:58

by Colin King

[permalink] [raw]

Subject: [PATCH] mt7601u: phy: simplify zero check on val

---

From: Colin Ian King <[email protected]>

Currently the zero check on val to break out of a loop
is a little obscure. Replace the val is zero and break check
with a loop while value is non-zero.

Signed-off-by: Colin Ian King <[email protected]>
---
drivers/net/wireless/mediatek/mt7601u/phy.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
index 06f5702ab4bd..4e0e473caae1 100644
--- a/drivers/net/wireless/mediatek/mt7601u/phy.c
+++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
@@ -213,9 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)

do {
val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
- if (val && ~val)
- break;
- } while (--i);
+ } while (val && --i);

if (!i) {
dev_err(dev->dev, "Error: BBP is not ready\n");
--
2.20.1

2019-09-20 19:48:56

by Robin Murphy

[permalink] [raw]

Subject: Re: [PATCH] mt7601u: phy: simplify zero check on val

---

On 20/09/2019 13:54, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> Currently the zero check on val to break out of a loop
> is a little obscure. Replace the val is zero and break check
> with a loop while value is non-zero.
>
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/net/wireless/mediatek/mt7601u/phy.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
> index 06f5702ab4bd..4e0e473caae1 100644
> --- a/drivers/net/wireless/mediatek/mt7601u/phy.c
> +++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
> @@ -213,9 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
>
> do {
> val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
> - if (val && ~val)
> - break;

AFAICS, this effectively implements "while (val == 0 || val == 0xff)",
which is not at all equivalent to "while(val)"... :/

Robin.

> - } while (--i);
> + } while (val && --i);
>
> if (!i) {
> dev_err(dev->dev, "Error: BBP is not ready\n");
>

2019-09-20 20:12:53

by Lorenzo Bianconi

[permalink] [raw]

Subject: Re: [PATCH] mt7601u: phy: simplify zero check on val

---

> From: Colin Ian King <[email protected]>
>
> Currently the zero check on val to break out of a loop
> is a little obscure. Replace the val is zero and break check
> with a loop while value is non-zero.
>
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/net/wireless/mediatek/mt7601u/phy.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
> index 06f5702ab4bd..4e0e473caae1 100644
> --- a/drivers/net/wireless/mediatek/mt7601u/phy.c
> +++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
> @@ -213,9 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
>
> do {
> val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
> - if (val && ~val)
> - break;

I think this is not correct since (not considering the cast) we should break
from the loop if val != 0 and val != 0xff, so the right approach I guess is:

diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
index 06f5702ab4bd..d863ab4a66c9 100644
--- a/drivers/net/wireless/mediatek/mt7601u/phy.c
+++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
@@ -213,7 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)

do {
val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
- if (val && ~val)
+ if (val && val != 0xff)
break;
} while (--i);

> - } while (--i);
> + } while (val && --i);
>
> if (!i) {
> dev_err(dev->dev, "Error: BBP is not ready\n");
> --
> 2.20.1
>

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2019-09-22 19:00:01

by Jakub Kicinski

[permalink] [raw]

Subject: Re: [PATCH] mt7601u: phy: simplify zero check on val

---

On Fri, 20 Sep 2019 15:58:17 +0200, Lorenzo Bianconi wrote:
> I think this is not correct since (not considering the cast) we should break
> from the loop if val != 0 and val != 0xff, so the right approach I guess is:
>
> diff --git a/drivers/net/wireless/mediatek/mt7601u/phy.c b/drivers/net/wireless/mediatek/mt7601u/phy.c
> index 06f5702ab4bd..d863ab4a66c9 100644
> --- a/drivers/net/wireless/mediatek/mt7601u/phy.c
> +++ b/drivers/net/wireless/mediatek/mt7601u/phy.c
> @@ -213,7 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
>
> do {
> val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
> - if (val && ~val)
> + if (val && val != 0xff)
> break;
> } while (--i);

Yup, feel free to add my ack if you post this, Lorenzo.