[PATCH] serial: 8250_dw: handle reset control deassert error

[PATCH] serial: 8250_dw: handle reset control deassert error

[Artem Shimko]

Check the return value of reset_control_deassert() in the probe
function to prevent continuing probe when reset deassertion fails.

Previously, reset_control_deassert() was called without checking its
return value, which could lead to probe continuing even when the
device reset wasn't properly deasserted.

The fix checks the return value and returns an error with dev_err_probe()
if reset deassertion fails, providing better error handling and
diagnostics.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
---
Hello maintainers and reviewers,

This patch adds proper error handling for reset_control_deassert() in the 
DesignWare 8250 serial driver probe function.

Currently, if reset deassertion fails, the driver continues probing which
could lead to operating a UART device that is still held in reset. This patch
ensures we properly check the return value and fail the probe with a
meaningful error message if reset deassertion fails.

The change follows the same pattern as other drivers handling reset controls
and provides consistent error handling behavior.

Thank you for your consideration.

Best regards,
Artem Shimko

 drivers/tty/serial/8250/8250_dw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a53ba04d9770..710ae4d40aec 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -635,7 +635,9 @@ static int dw8250_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rst))
 		return PTR_ERR(data->rst);
 
-	reset_control_deassert(data->rst);
+	err = reset_control_deassert(data->rst);
+	if (err)
+		return dev_err_probe(dev, err, "failed to deassert resets\n");
 
 	err = devm_add_action_or_reset(dev, dw8250_reset_control_assert, data->rst);
 	if (err)
-- 
2.43.0

Re: [PATCH] serial: 8250_dw: handle reset control deassert error

[Andy Shevchenko]

On Thu, Oct 09, 2025 at 11:13:08AM +0300, Artem Shimko wrote:
> Check the return value of reset_control_deassert() in the probe
> function to prevent continuing probe when reset deassertion fails.
> 
> Previously, reset_control_deassert() was called without checking its
> return value, which could lead to probe continuing even when the
> device reset wasn't properly deasserted.
> 
> The fix checks the return value and returns an error with dev_err_probe()
> if reset deassertion fails, providing better error handling and
> diagnostics.

If it's not applied yet, it deserves the Fixes tag, I believe.

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2] serial: 8250_dw: handle reset control deassert error

[Artem Shimko]

Check the return value of reset_control_deassert() in the probe
function to prevent continuing probe when reset deassertion fails.

Previously, reset_control_deassert() was called without checking its
return value, which could lead to probe continuing even when the
device reset wasn't properly deasserted.

The fix checks the return value and returns an error with dev_err_probe()
if reset deassertion fails, providing better error handling and
diagnostics.

Fixes: acbdad8dd1ab ("serial: 8250_dw: simplify optional reset handling")
Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
---
Hi Andy,

Thank you for your review.

The v1 patch hasn't been applied.

I've addressed your comments in v2 - could you please take a look when you have time?

Best regards,
Artem Shimko

ChangeLog:
  v1:
    * https://lore.kernel.org/all/20251009081309.2021600-1-a.shimko.dev@gmail.com/T/#u
  v2:
    * Add fix tag to commit description

 drivers/tty/serial/8250/8250_dw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a53ba04d9770..710ae4d40aec 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -635,7 +635,9 @@ static int dw8250_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rst))
 		return PTR_ERR(data->rst);
 
-	reset_control_deassert(data->rst);
+	err = reset_control_deassert(data->rst);
+	if (err)
+		return dev_err_probe(dev, err, "failed to deassert resets\n");
 
 	err = devm_add_action_or_reset(dev, dw8250_reset_control_assert, data->rst);
 	if (err)
-- 
2.43.0

Re: [PATCH v2] serial: 8250_dw: handle reset control deassert error

[Greg KH]

On Sun, Oct 19, 2025 at 11:53:25AM +0300, Artem Shimko wrote:
> Check the return value of reset_control_deassert() in the probe
> function to prevent continuing probe when reset deassertion fails.
> 
> Previously, reset_control_deassert() was called without checking its
> return value, which could lead to probe continuing even when the
> device reset wasn't properly deasserted.
> 
> The fix checks the return value and returns an error with dev_err_probe()
> if reset deassertion fails, providing better error handling and
> diagnostics.
> 
> Fixes: acbdad8dd1ab ("serial: 8250_dw: simplify optional reset handling")
> Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
> ---
> Hi Andy,
> 
> Thank you for your review.
> 
> The v1 patch hasn't been applied.
> 
> I've addressed your comments in v2 - could you please take a look when you have time?
> 
> Best regards,
> Artem Shimko
> 
> ChangeLog:
>   v1:
>     * https://lore.kernel.org/all/20251009081309.2021600-1-a.shimko.dev@gmail.com/T/#u
>   v2:
>     * Add fix tag to commit description
> 
>  drivers/tty/serial/8250/8250_dw.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index a53ba04d9770..710ae4d40aec 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -635,7 +635,9 @@ static int dw8250_probe(struct platform_device *pdev)
>  	if (IS_ERR(data->rst))
>  		return PTR_ERR(data->rst);
>  
> -	reset_control_deassert(data->rst);
> +	err = reset_control_deassert(data->rst);
> +	if (err)
> +		return dev_err_probe(dev, err, "failed to deassert resets\n");
>  
>  	err = devm_add_action_or_reset(dev, dw8250_reset_control_assert, data->rst);
>  	if (err)
> -- 
> 2.43.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

[PATCH v3] serial: 8250_dw: handle reset control deassert error

[Artem Shimko]

Check the return value of reset_control_deassert() in the probe
function to prevent continuing probe when reset deassertion fails.

Previously, reset_control_deassert() was called without checking its
return value, which could lead to probe continuing even when the
device reset wasn't properly deasserted.

The fix checks the return value and returns an error with dev_err_probe()
if reset deassertion fails, providing better error handling and
diagnostics.

Fixes: acbdad8dd1ab ("serial: 8250_dw: simplify optional reset handling")
Cc: stable@vger.kernel.org
Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
---
Hi,

Done.

Thank you!

Best regards,
Artem Shimko

ChangeLog:
  v1:
    * https://lore.kernel.org/all/20251009081309.2021600-1-a.shimko.dev@gmail.com/T/#u
  v2:
    * https://lore.kernel.org/all/20251019085325.250657-1-a.shimko.dev@gmail.com/
  v3:
  	* Add Cc: stable@vger.kernel.org

 drivers/tty/serial/8250/8250_dw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a53ba04d9770..710ae4d40aec 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -635,7 +635,9 @@ static int dw8250_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rst))
 		return PTR_ERR(data->rst);
 
-	reset_control_deassert(data->rst);
+	err = reset_control_deassert(data->rst);
+	if (err)
+		return dev_err_probe(dev, err, "failed to deassert resets\n");
 
 	err = devm_add_action_or_reset(dev, dw8250_reset_control_assert, data->rst);
 	if (err)
-- 
2.43.0