From: Lino Sanfilippo <[email protected]>
In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus
termination is supported by the driver. This prevents from allocating
and holding a GPIO descriptor for the drivers lifetimg that will never be
used.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
NOTE:
This patch follows the design decision that "rs485_supported" is
set by the driver at initialization and cannot be modified
afterwards. However the better approach would be to let the serial
core modify the termination GPIO support setting based on the
existence of a termination GPIO. If "rs485_supported" is not a
read-only value any more in future the logic implemented in this
patch should be adjusted accordingly.
drivers/tty/serial/serial_core.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 85ef7ef00b82..3768663dfa4d 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3404,6 +3404,16 @@ int uart_get_rs485_mode(struct uart_port *port)
*/
port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
GPIOD_OUT_LOW);
+
+ if (port->rs485_term_gpio &&
+ !(port->rs485_supported->flags & SER_RS485_TERMINATE_BUS)) {
+ dev_warn(port->dev,
+ "%s (%d): RS485 termination gpio not supported by driver\n",
+ port->name, port->line);
+ devm_gpiod_put(dev, port->rs485_term_gpio);
+ port->rs485_term_gpio = NULL;
+ }
+
if (IS_ERR(port->rs485_term_gpio)) {
ret = PTR_ERR(port->rs485_term_gpio);
port->rs485_term_gpio = NULL;
--
2.25.1
On Sun, Jul 3, 2022 at 7:02 PM Lino Sanfilippo <[email protected]> wrote:
>
> From: Lino Sanfilippo <[email protected]>
>
> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus
> termination is supported by the driver. This prevents from allocating
> and holding a GPIO descriptor for the drivers lifetimg that will never be
lifetiming
> used.
...
> port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
> GPIOD_OUT_LOW);
> +
> + if (port->rs485_term_gpio &&
This check is incorrect. Either you need to move that after error
checking (that's what I personally prefer), or use !IS_ERR_OR_NULL().
> + !(port->rs485_supported->flags & SER_RS485_TERMINATE_BUS)) {
> + dev_warn(port->dev,
> + "%s (%d): RS485 termination gpio not supported by driver\n",
> + port->name, port->line);
> + devm_gpiod_put(dev, port->rs485_term_gpio);
> + port->rs485_term_gpio = NULL;
> + }
> +
> if (IS_ERR(port->rs485_term_gpio)) {
> ret = PTR_ERR(port->rs485_term_gpio);
> port->rs485_term_gpio = NULL;
--
With Best Regards,
Andy Shevchenko
Hi,
On 03.07.22 20:27, Andy Shevchenko wrote:
> On Sun, Jul 3, 2022 at 7:02 PM Lino Sanfilippo <[email protected]> wrote:
>>
>> From: Lino Sanfilippo <[email protected]>
>>
>> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus
>> termination is supported by the driver. This prevents from allocating
>> and holding a GPIO descriptor for the drivers lifetimg that will never be
>
> lifetiming
>
>> used.
>
> ...
>
>> port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
>> GPIOD_OUT_LOW);
>> +
>> + if (port->rs485_term_gpio &&
>
> This check is incorrect. Either you need to move that after error
> checking (that's what I personally prefer), or use !IS_ERR_OR_NULL().
>
Right, a stupid mistake. I will fix this, thanks!
Regards,
Lino
On Sun, 3 Jul 2022, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <[email protected]>
>
> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus
> termination is supported by the driver. This prevents from allocating
> and holding a GPIO descriptor for the drivers lifetimg that will never be
> used.
>
> Signed-off-by: Lino Sanfilippo <[email protected]>
> ---
>
> NOTE:
> This patch follows the design decision that "rs485_supported" is
> set by the driver at initialization and cannot be modified
> afterwards. However the better approach would be to let the serial
> core modify the termination GPIO support setting based on the
> existence of a termination GPIO. If "rs485_supported" is not a
> read-only value any more in future the logic implemented in this
> patch should be adjusted accordingly.
>
> drivers/tty/serial/serial_core.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 85ef7ef00b82..3768663dfa4d 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -3404,6 +3404,16 @@ int uart_get_rs485_mode(struct uart_port *port)
> */
> port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
> GPIOD_OUT_LOW);
> +
> + if (port->rs485_term_gpio &&
> + !(port->rs485_supported->flags & SER_RS485_TERMINATE_BUS)) {
> + dev_warn(port->dev,
> + "%s (%d): RS485 termination gpio not supported by driver\n",
> + port->name, port->line);
> + devm_gpiod_put(dev, port->rs485_term_gpio);
> + port->rs485_term_gpio = NULL;
> + }
> +
> if (IS_ERR(port->rs485_term_gpio)) {
> ret = PTR_ERR(port->rs485_term_gpio);
> port->rs485_term_gpio = NULL;
I sent a series to embed supported_rs485 to uart_port and manage
SER_RS485_TERMINATE_BUS properly so I think this won't be necessary
with that?
--
i.
On 04.07.22 11:55, Ilpo Järvinen wrote:
> On Sun, 3 Jul 2022, Lino Sanfilippo wrote:
>
>> From: Lino Sanfilippo <[email protected]>
>>
>> In uart_get_rs485_mode() only try to get a termination GPIO if RS485 bus
>> termination is supported by the driver. This prevents from allocating
>> and holding a GPIO descriptor for the drivers lifetimg that will never be
>> used.
>>
>> Signed-off-by: Lino Sanfilippo <[email protected]>
>> ---
>>
>> NOTE:
>> This patch follows the design decision that "rs485_supported" is
>> set by the driver at initialization and cannot be modified
>> afterwards. However the better approach would be to let the serial
>> core modify the termination GPIO support setting based on the
>> existence of a termination GPIO. If "rs485_supported" is not a
>> read-only value any more in future the logic implemented in this
>> patch should be adjusted accordingly.
>>
>> drivers/tty/serial/serial_core.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
>> index 85ef7ef00b82..3768663dfa4d 100644
>> --- a/drivers/tty/serial/serial_core.c
>> +++ b/drivers/tty/serial/serial_core.c
>> @@ -3404,6 +3404,16 @@ int uart_get_rs485_mode(struct uart_port *port)
>> */
>> port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
>> GPIOD_OUT_LOW);
>> +
>> + if (port->rs485_term_gpio &&
>> + !(port->rs485_supported->flags & SER_RS485_TERMINATE_BUS)) {
>> + dev_warn(port->dev,
>> + "%s (%d): RS485 termination gpio not supported by driver\n",
>> + port->name, port->line);
>> + devm_gpiod_put(dev, port->rs485_term_gpio);
>> + port->rs485_term_gpio = NULL;
>> + }
>> +
>> if (IS_ERR(port->rs485_term_gpio)) {
>> ret = PTR_ERR(port->rs485_term_gpio);
>> port->rs485_term_gpio = NULL;
>
> I sent a series to embed supported_rs485 to uart_port and manage
> SER_RS485_TERMINATE_BUS properly so I think this won't be necessary
> with that?
>
>
This is why I wrote the "NOTE" above. But yes, this patch is not needed
any more. I will drop it in the next version.
Regards,
Lino