This patch adds a check for the GPIOs property existence, before the
GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
support is added (2nd patch in this patch series) on x86 platforms using
ACPI.
Here Mika's comments from 2016-08-09:
"
I noticed that with v4.8-rc1 serial console of some of our Broxton
systems does not work properly anymore. I'm able to see output but input
does not work.
I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
("tty/serial/8250: use mctrl_gpio helpers").
The reason why it fails is that in ACPI we do not have names for GPIOs
(except when _DSD is used) so we use the "idx" to index into _CRS GPIO
resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
UART device in Broxton has following (simplified) ACPI description:
Device (URT4)
{
...
Name (_CRS, ResourceTemplate () {
GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
"\\_SB.GPO0", 0x00, ResourceConsumer)
{
0x003A
}
GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
"\\_SB.GPO0", 0x00, ResourceConsumer)
{
0x003D
}
})
In this case it finds the first GPIO (0x003A which happens to be RX pin
for that UART), turns it into GPIO which then breaks input for the UART
device. This also breaks systems with bluetooth connected to UART (those
typically have some GPIOs in their _CRS).
Any ideas how to fix this?
We cannot just drop the _CRS index lookup fallback because that would
break many existing machines out there so maybe we can limit this to
only DT enabled machines. Or alternatively probe if the property first
exists before trying to acquire the GPIOs (using
device_property_present()).
"
This patch implements the fix suggested by Mika in his statement above.
Signed-off-by: Stefan Roese <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Cc: Mika Westerberg <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Yegor Yefremov <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Giulio Benetti <[email protected]>
---
v6:
- No change
v5:
- Simplified the code a bit (Andy)
- Added gpio_str == NULL handling (Andy)
v4:
- Add missing free() calls (Johan)
- Added Mika's reviewed by tag
- Added Johan to Cc
v3:
- No change
v2:
- Include the problem description and analysis from Mika into the commit
text, as suggested by Greg.
drivers/tty/serial/serial_mctrl_gpio.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index 39ed56214cd3..65348887a749 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -116,6 +116,19 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
for (i = 0; i < UART_GPIO_MAX; i++) {
enum gpiod_flags flags;
+ char *gpio_str;
+ bool present;
+
+ /* Check if GPIO property exists and continue if not */
+ gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
+ mctrl_gpios_desc[i].name);
+ if (!gpio_str)
+ continue;
+
+ present = device_property_present(dev, gpio_str);
+ kfree(gpio_str);
+ if (!present)
+ continue;
if (mctrl_gpios_desc[i].dir_out)
flags = GPIOD_OUT_LOW;
--
2.22.0
On Thu, Jun 13, 2019 at 05:45:40PM +0200, Stefan Roese wrote:
> This patch adds a check for the GPIOs property existence, before the
> GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
> support is added (2nd patch in this patch series) on x86 platforms using
> ACPI.
>
> Here Mika's comments from 2016-08-09:
>
> "
> I noticed that with v4.8-rc1 serial console of some of our Broxton
> systems does not work properly anymore. I'm able to see output but input
> does not work.
>
> I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
> ("tty/serial/8250: use mctrl_gpio helpers").
>
> The reason why it fails is that in ACPI we do not have names for GPIOs
> (except when _DSD is used) so we use the "idx" to index into _CRS GPIO
> resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
> calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
> UART device in Broxton has following (simplified) ACPI description:
>
> Device (URT4)
> {
> ...
> Name (_CRS, ResourceTemplate () {
> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> "\\_SB.GPO0", 0x00, ResourceConsumer)
> {
> 0x003A
> }
> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> "\\_SB.GPO0", 0x00, ResourceConsumer)
> {
> 0x003D
> }
> })
>
> In this case it finds the first GPIO (0x003A which happens to be RX pin
> for that UART), turns it into GPIO which then breaks input for the UART
> device. This also breaks systems with bluetooth connected to UART (those
> typically have some GPIOs in their _CRS).
>
> Any ideas how to fix this?
>
> We cannot just drop the _CRS index lookup fallback because that would
> break many existing machines out there so maybe we can limit this to
> only DT enabled machines. Or alternatively probe if the property first
> exists before trying to acquire the GPIOs (using
> device_property_present()).
> "
>
> This patch implements the fix suggested by Mika in his statement above.
>
Reviewed-by: Andy Shevchenko <[email protected]>
> Signed-off-by: Stefan Roese <[email protected]>
> Reviewed-by: Mika Westerberg <[email protected]>
> Cc: Mika Westerberg <[email protected]>
> Cc: Andy Shevchenko <[email protected]>
> Cc: Yegor Yefremov <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Cc: Giulio Benetti <[email protected]>
> ---
> v6:
> - No change
>
> v5:
> - Simplified the code a bit (Andy)
> - Added gpio_str == NULL handling (Andy)
>
> v4:
> - Add missing free() calls (Johan)
> - Added Mika's reviewed by tag
> - Added Johan to Cc
>
> v3:
> - No change
>
> v2:
> - Include the problem description and analysis from Mika into the commit
> text, as suggested by Greg.
>
> drivers/tty/serial/serial_mctrl_gpio.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
> index 39ed56214cd3..65348887a749 100644
> --- a/drivers/tty/serial/serial_mctrl_gpio.c
> +++ b/drivers/tty/serial/serial_mctrl_gpio.c
> @@ -116,6 +116,19 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
>
> for (i = 0; i < UART_GPIO_MAX; i++) {
> enum gpiod_flags flags;
> + char *gpio_str;
> + bool present;
> +
> + /* Check if GPIO property exists and continue if not */
> + gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
> + mctrl_gpios_desc[i].name);
> + if (!gpio_str)
> + continue;
> +
> + present = device_property_present(dev, gpio_str);
> + kfree(gpio_str);
> + if (!present)
> + continue;
>
> if (mctrl_gpios_desc[i].dir_out)
> flags = GPIOD_OUT_LOW;
> --
> 2.22.0
>
--
With Best Regards,
Andy Shevchenko
On Thu, Jun 13, 2019 at 7:08 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Thu, Jun 13, 2019 at 05:45:40PM +0200, Stefan Roese wrote:
> > This patch adds a check for the GPIOs property existence, before the
> > GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
> > support is added (2nd patch in this patch series) on x86 platforms using
> > ACPI.
> >
> > Here Mika's comments from 2016-08-09:
> >
> > "
> > I noticed that with v4.8-rc1 serial console of some of our Broxton
> > systems does not work properly anymore. I'm able to see output but input
> > does not work.
> >
> > I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
> > ("tty/serial/8250: use mctrl_gpio helpers").
> >
> > The reason why it fails is that in ACPI we do not have names for GPIOs
> > (except when _DSD is used) so we use the "idx" to index into _CRS GPIO
> > resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
> > calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
> > UART device in Broxton has following (simplified) ACPI description:
> >
> > Device (URT4)
> > {
> > ...
> > Name (_CRS, ResourceTemplate () {
> > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> > "\\_SB.GPO0", 0x00, ResourceConsumer)
> > {
> > 0x003A
> > }
> > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> > "\\_SB.GPO0", 0x00, ResourceConsumer)
> > {
> > 0x003D
> > }
> > })
> >
> > In this case it finds the first GPIO (0x003A which happens to be RX pin
> > for that UART), turns it into GPIO which then breaks input for the UART
> > device. This also breaks systems with bluetooth connected to UART (those
> > typically have some GPIOs in their _CRS).
> >
> > Any ideas how to fix this?
> >
> > We cannot just drop the _CRS index lookup fallback because that would
> > break many existing machines out there so maybe we can limit this to
> > only DT enabled machines. Or alternatively probe if the property first
> > exists before trying to acquire the GPIOs (using
> > device_property_present()).
> > "
> >
> > This patch implements the fix suggested by Mika in his statement above.
> >
>
> Reviewed-by: Andy Shevchenko <[email protected]>
I cannot compile the driver without adding #include <linux/property.h>
to drivers/tty/serial/serial_mctrl_gpio.c.
My platform is AM335X (OMAP3). I've tried the patches both against the
main repo and also tty-next.
Other than that everything is working.
Yegor
> > Signed-off-by: Stefan Roese <[email protected]>
> > Reviewed-by: Mika Westerberg <[email protected]>
> > Cc: Mika Westerberg <[email protected]>
> > Cc: Andy Shevchenko <[email protected]>
> > Cc: Yegor Yefremov <[email protected]>
> > Cc: Greg Kroah-Hartman <[email protected]>
> > Cc: Giulio Benetti <[email protected]>
> > ---
> > v6:
> > - No change
> >
> > v5:
> > - Simplified the code a bit (Andy)
> > - Added gpio_str == NULL handling (Andy)
> >
> > v4:
> > - Add missing free() calls (Johan)
> > - Added Mika's reviewed by tag
> > - Added Johan to Cc
> >
> > v3:
> > - No change
> >
> > v2:
> > - Include the problem description and analysis from Mika into the commit
> > text, as suggested by Greg.
> >
> > drivers/tty/serial/serial_mctrl_gpio.c | 13 +++++++++++++
> > 1 file changed, 13 insertions(+)
> >
> > diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
> > index 39ed56214cd3..65348887a749 100644
> > --- a/drivers/tty/serial/serial_mctrl_gpio.c
> > +++ b/drivers/tty/serial/serial_mctrl_gpio.c
> > @@ -116,6 +116,19 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
> >
> > for (i = 0; i < UART_GPIO_MAX; i++) {
> > enum gpiod_flags flags;
> > + char *gpio_str;
> > + bool present;
> > +
> > + /* Check if GPIO property exists and continue if not */
> > + gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
> > + mctrl_gpios_desc[i].name);
> > + if (!gpio_str)
> > + continue;
> > +
> > + present = device_property_present(dev, gpio_str);
> > + kfree(gpio_str);
> > + if (!present)
> > + continue;
> >
> > if (mctrl_gpios_desc[i].dir_out)
> > flags = GPIOD_OUT_LOW;
> > --
> > 2.22.0
> >
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
On 14.06.19 11:04, Yegor Yefremov wrote:
> On Thu, Jun 13, 2019 at 7:08 PM Andy Shevchenko
> <[email protected]> wrote:
>>
>> On Thu, Jun 13, 2019 at 05:45:40PM +0200, Stefan Roese wrote:
>>> This patch adds a check for the GPIOs property existence, before the
>>> GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
>>> support is added (2nd patch in this patch series) on x86 platforms using
>>> ACPI.
>>>
>>> Here Mika's comments from 2016-08-09:
>>>
>>> "
>>> I noticed that with v4.8-rc1 serial console of some of our Broxton
>>> systems does not work properly anymore. I'm able to see output but input
>>> does not work.
>>>
>>> I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
>>> ("tty/serial/8250: use mctrl_gpio helpers").
>>>
>>> The reason why it fails is that in ACPI we do not have names for GPIOs
>>> (except when _DSD is used) so we use the "idx" to index into _CRS GPIO
>>> resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
>>> calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
>>> UART device in Broxton has following (simplified) ACPI description:
>>>
>>> Device (URT4)
>>> {
>>> ...
>>> Name (_CRS, ResourceTemplate () {
>>> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
>>> "\\_SB.GPO0", 0x00, ResourceConsumer)
>>> {
>>> 0x003A
>>> }
>>> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
>>> "\\_SB.GPO0", 0x00, ResourceConsumer)
>>> {
>>> 0x003D
>>> }
>>> })
>>>
>>> In this case it finds the first GPIO (0x003A which happens to be RX pin
>>> for that UART), turns it into GPIO which then breaks input for the UART
>>> device. This also breaks systems with bluetooth connected to UART (those
>>> typically have some GPIOs in their _CRS).
>>>
>>> Any ideas how to fix this?
>>>
>>> We cannot just drop the _CRS index lookup fallback because that would
>>> break many existing machines out there so maybe we can limit this to
>>> only DT enabled machines. Or alternatively probe if the property first
>>> exists before trying to acquire the GPIOs (using
>>> device_property_present()).
>>> "
>>>
>>> This patch implements the fix suggested by Mika in his statement above.
>>>
>>
>> Reviewed-by: Andy Shevchenko <[email protected]>
>
> I cannot compile the driver without adding #include <linux/property.h>
> to drivers/tty/serial/serial_mctrl_gpio.c.
>
> My platform is AM335X (OMAP3). I've tried the patches both against the
> main repo and also tty-next.
>
> Other than that everything is working.
Thanks for reporting. I'll wait a bit for other review comments and
tests (thanks Andy) and will then send v7 with this header included
(and compile tested on OMAP3) later next week.
BTW: Could you please add a Tested-by-tag with the next version?
Thanks,
Stefan
On Fri, Jun 14, 2019 at 11:29 AM Stefan Roese <[email protected]> wrote:
>
> On 14.06.19 11:04, Yegor Yefremov wrote:
> > On Thu, Jun 13, 2019 at 7:08 PM Andy Shevchenko
> > <[email protected]> wrote:
> >>
> >> On Thu, Jun 13, 2019 at 05:45:40PM +0200, Stefan Roese wrote:
> >>> This patch adds a check for the GPIOs property existence, before the
> >>> GPIO is requested. This fixes an issue seen when the 8250 mctrl_gpio
> >>> support is added (2nd patch in this patch series) on x86 platforms using
> >>> ACPI.
> >>>
> >>> Here Mika's comments from 2016-08-09:
> >>>
> >>> "
> >>> I noticed that with v4.8-rc1 serial console of some of our Broxton
> >>> systems does not work properly anymore. I'm able to see output but input
> >>> does not work.
> >>>
> >>> I bisected it down to commit 4ef03d328769eddbfeca1f1c958fdb181a69c341
> >>> ("tty/serial/8250: use mctrl_gpio helpers").
> >>>
> >>> The reason why it fails is that in ACPI we do not have names for GPIOs
> >>> (except when _DSD is used) so we use the "idx" to index into _CRS GPIO
> >>> resources. Now mctrl_gpio_init_noauto() goes through a list of GPIOs
> >>> calling devm_gpiod_get_index_optional() passing "idx" of 0 for each. The
> >>> UART device in Broxton has following (simplified) ACPI description:
> >>>
> >>> Device (URT4)
> >>> {
> >>> ...
> >>> Name (_CRS, ResourceTemplate () {
> >>> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> >>> "\\_SB.GPO0", 0x00, ResourceConsumer)
> >>> {
> >>> 0x003A
> >>> }
> >>> GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> >>> "\\_SB.GPO0", 0x00, ResourceConsumer)
> >>> {
> >>> 0x003D
> >>> }
> >>> })
> >>>
> >>> In this case it finds the first GPIO (0x003A which happens to be RX pin
> >>> for that UART), turns it into GPIO which then breaks input for the UART
> >>> device. This also breaks systems with bluetooth connected to UART (those
> >>> typically have some GPIOs in their _CRS).
> >>>
> >>> Any ideas how to fix this?
> >>>
> >>> We cannot just drop the _CRS index lookup fallback because that would
> >>> break many existing machines out there so maybe we can limit this to
> >>> only DT enabled machines. Or alternatively probe if the property first
> >>> exists before trying to acquire the GPIOs (using
> >>> device_property_present()).
> >>> "
> >>>
> >>> This patch implements the fix suggested by Mika in his statement above.
> >>>
> >>
> >> Reviewed-by: Andy Shevchenko <[email protected]>
> >
> > I cannot compile the driver without adding #include <linux/property.h>
> > to drivers/tty/serial/serial_mctrl_gpio.c.
> >
> > My platform is AM335X (OMAP3). I've tried the patches both against the
> > main repo and also tty-next.
> >
> > Other than that everything is working.
>
> Thanks for reporting. I'll wait a bit for other review comments and
> tests (thanks Andy) and will then send v7 with this header included
> (and compile tested on OMAP3) later next week.
>
> BTW: Could you please add a Tested-by-tag with the next version?
Will do.