2021-03-19 14:49:26

by Dan Carpenter

[permalink] [raw]
Subject: [PATCH] wilc1000: fix a loop timeout condition

If the loop fails, the "while(trials--) {" loop will exit with "trials"
set to -1. The test for that expects it to end with "trials" set to 0
so the warning message will not be printed.

Fix this by changing from a post-op to a pre-op. This does mean that
we only make 99 attempts instead of 100 but that's okay.

Fixes: f135a1571a05 ("wilc1000: Support chip sleep over SPI")
Signed-off-by: Dan Carpenter <[email protected]>
---
drivers/net/wireless/microchip/wilc1000/wlan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/wlan.c b/drivers/net/wireless/microchip/wilc1000/wlan.c
index d4a90c490084..2030fc7f53ca 100644
--- a/drivers/net/wireless/microchip/wilc1000/wlan.c
+++ b/drivers/net/wireless/microchip/wilc1000/wlan.c
@@ -575,7 +575,7 @@ void chip_allow_sleep(struct wilc *wilc)
to_host_from_fw_bit = WILC_SPI_FW_TO_HOST_BIT;
}

- while (trials--) {
+ while (--trials) {
ret = hif_func->hif_read_reg(wilc, to_host_from_fw_reg, &reg);
if (ret)
return;
--
2.30.2


2021-03-19 16:11:00

by Ajay Singh

[permalink] [raw]
Subject: Re: [PATCH] wilc1000: fix a loop timeout condition


On 19/03/21 8:17 pm, Dan Carpenter wrote:
>
> If the loop fails, the "while(trials--) {" loop will exit with "trials"
> set to -1. The test for that expects it to end with "trials" set to 0
> so the warning message will not be printed.
>
> Fix this by changing from a post-op to a pre-op. This does mean that
> we only make 99 attempts instead of 100 but that's okay.
>
> Fixes: f135a1571a05 ("wilc1000: Support chip sleep over SPI")
> Signed-off-by: Dan Carpenter <[email protected]>

Thanks Dan.

Acked-by: Ajay Singh <[email protected]>

> ---
> drivers/net/wireless/microchip/wilc1000/wlan.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/microchip/wilc1000/wlan.c b/drivers/net/wireless/microchip/wilc1000/wlan.c
> index d4a90c490084..2030fc7f53ca 100644
> --- a/drivers/net/wireless/microchip/wilc1000/wlan.c
> +++ b/drivers/net/wireless/microchip/wilc1000/wlan.c
> @@ -575,7 +575,7 @@ void chip_allow_sleep(struct wilc *wilc)
> to_host_from_fw_bit = WILC_SPI_FW_TO_HOST_BIT;
> }
>
> - while (trials--) {
> + while (--trials) {
> ret = hif_func->hif_read_reg(wilc, to_host_from_fw_reg, &reg);
> if (ret)
> return;
> --
> 2.30.2
>

2021-03-29 18:48:54

by David Mosberger-Tang

[permalink] [raw]
Subject: Re: [PATCH] wilc1000: fix a loop timeout condition

On Fri, 2021-03-19 at 16:09 +0000, [email protected] wrote:
> On 19/03/21 8:17 pm, Dan Carpenter wrote:
> > If the loop fails, the "while(trials--) {" loop will exit with "trials"
> > set to -1. The test for that expects it to end with "trials" set to 0
> > so the warning message will not be printed.
> >
> > Fix this by changing from a post-op to a pre-op. This does mean that
> > we only make 99 attempts instead of 100 but that's okay.
> >
> > Fixes: f135a1571a05 ("wilc1000: Support chip sleep over SPI")
> > Signed-off-by: Dan Carpenter <[email protected]>
>
> Thanks Dan.

Good catch, but wouldn't it be better to fix the time-out check
condition instead? Something a long the lines of:

--- drivers/net/wireless/microchip/wilc1000/wlan.c~ 2021-03-29 12:44:52.066039259 -0600
+++ drivers/net/wireless/microchip/wilc1000/wlan.c 2021-03-29 12:40:29.176365116 -0600
@@ -457,7 +457,7 @@
u32 wakeup_reg, wakeup_bit;
u32 to_host_from_fw_reg, to_host_from_fw_bit;
u32 from_host_to_fw_reg, from_host_to_fw_bit;
- u32 trials = 100;
+ int trials = 100;
int ret;

if (wilc->io_type == WILC_HIF_SDIO) {
@@ -483,7 +483,7 @@
if ((reg & to_host_from_fw_bit) == 0)
break;
}
- if (!trials)
+ if (trials < 0)
pr_warn("FW not responding\n");

/* Clear bit 1 */


This way, the loop could actually get executed the number of times
indicated by the initialization of "trial" before issuing a warning
message.

--david

> Acked-by: Ajay Singh <[email protected]>
>
> > ---
> > drivers/net/wireless/microchip/wilc1000/wlan.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/microchip/wilc1000/wlan.c b/drivers/net/wireless/microchip/wilc1000/wlan.c
> > index d4a90c490084..2030fc7f53ca 100644
> > --- a/drivers/net/wireless/microchip/wilc1000/wlan.c
> > +++ b/drivers/net/wireless/microchip/wilc1000/wlan.c
> > @@ -575,7 +575,7 @@ void chip_allow_sleep(struct wilc *wilc)
> > to_host_from_fw_bit = WILC_SPI_FW_TO_HOST_BIT;
> > }
> >
> > - while (trials--) {
> > + while (--trials) {
> > ret = hif_func->hif_read_reg(wilc, to_host_from_fw_reg, &reg);
> > if (ret)
> > return;
> > --
> > 2.30.2
> >

2021-03-30 08:55:41

by Dan Carpenter

[permalink] [raw]
Subject: Re: [PATCH] wilc1000: fix a loop timeout condition

On Mon, Mar 29, 2021 at 12:47:15PM -0600, David Mosberger-Tang wrote:
> On Fri, 2021-03-19 at 16:09 +0000, [email protected] wrote:
> > On 19/03/21 8:17 pm, Dan Carpenter wrote:
> > > If the loop fails, the "while(trials--) {" loop will exit with "trials"
> > > set to -1. The test for that expects it to end with "trials" set to 0
> > > so the warning message will not be printed.
> > >
> > > Fix this by changing from a post-op to a pre-op. This does mean that
> > > we only make 99 attempts instead of 100 but that's okay.
> > >
> > > Fixes: f135a1571a05 ("wilc1000: Support chip sleep over SPI")
> > > Signed-off-by: Dan Carpenter <[email protected]>
> >
> > Thanks Dan.
>
> Good catch, but wouldn't it be better to fix the time-out check
> condition instead? Something a long the lines of:
>
> --- drivers/net/wireless/microchip/wilc1000/wlan.c~ 2021-03-29 12:44:52.066039259 -0600
> +++ drivers/net/wireless/microchip/wilc1000/wlan.c 2021-03-29 12:40:29.176365116 -0600
> @@ -457,7 +457,7 @@
> u32 wakeup_reg, wakeup_bit;
> u32 to_host_from_fw_reg, to_host_from_fw_bit;
> u32 from_host_to_fw_reg, from_host_to_fw_bit;
> - u32 trials = 100;
> + int trials = 100;
> int ret;
>
> if (wilc->io_type == WILC_HIF_SDIO) {
> @@ -483,7 +483,7 @@
> if ((reg & to_host_from_fw_bit) == 0)
> break;
> }
> - if (!trials)
> + if (trials < 0)
> pr_warn("FW not responding\n");
>
> /* Clear bit 1 */
>
>
> This way, the loop could actually get executed the number of times
> indicated by the initialization of "trial" before issuing a warning
> message.

Those numbers are just made up... It doesn't matter either way.

regards,
dan carpenter

2021-04-17 17:55:15

by Kalle Valo

[permalink] [raw]
Subject: Re: [PATCH] wilc1000: fix a loop timeout condition

Dan Carpenter <[email protected]> wrote:

> If the loop fails, the "while(trials--) {" loop will exit with "trials"
> set to -1. The test for that expects it to end with "trials" set to 0
> so the warning message will not be printed.
>
> Fix this by changing from a post-op to a pre-op. This does mean that
> we only make 99 attempts instead of 100 but that's okay.
>
> Fixes: f135a1571a05 ("wilc1000: Support chip sleep over SPI")
> Signed-off-by: Dan Carpenter <[email protected]>
> Acked-by: Ajay Singh <[email protected]>

Patch applied to wireless-drivers-next.git, thanks.

2f51061edab9 wilc1000: fix a loop timeout condition

--
https://patchwork.kernel.org/project/linux-wireless/patch/YFS5gx/[email protected]/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches