Not all GPIO pins are exposed to the world and this is typically
described by not giving these lines particular names, commonly "" or
"NC".
With the recent introduction of '2cd64ae98f35 ("gpiolib: Disallow
identical line names in the same chip")' any gpiochip with multiple such
pins will refuse to probe.
Fix this by treating "" and "NC" as "no name specified" in
gpio_name_to_desc()
Fixes: 2cd64ae98f35 ("gpiolib: Disallow identical line names in the same chip")
Signed-off-by: Bjorn Andersson <[email protected]>
---
The introduction of 2cd64ae98f35 breaks pretty much all Qualcomm boards and
grepping the DT tree indicates that other vendors will have the same problem.
In addition to this the am335x-* boards will also needs "[NC]", "[ethernet]",
"[emmc"], "[i2c0]", "[SYSBOOT]" and "[JTAG]" added to this list to allow
booting v5.11 with the past and present dtb/dts files.
drivers/gpio/gpiolib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index b3340ba68471..407ba79ae571 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -302,7 +302,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
struct gpio_device *gdev;
unsigned long flags;
- if (!name)
+ if (!name || !strcmp(name, "") || !strcmp(name, "NC"))
return NULL;
spin_lock_irqsave(&gpio_lock, flags);
--
2.29.2
On Tue, Dec 15, 2020 at 6:02 PM Bjorn Andersson
<[email protected]> wrote:
>
> Not all GPIO pins are exposed to the world and this is typically
> described by not giving these lines particular names, commonly "" or
> "NC".
>
> With the recent introduction of '2cd64ae98f35 ("gpiolib: Disallow
> identical line names in the same chip")' any gpiochip with multiple such
> pins will refuse to probe.
>
> Fix this by treating "" and "NC" as "no name specified" in
> gpio_name_to_desc()
>
> Fixes: 2cd64ae98f35 ("gpiolib: Disallow identical line names in the same chip")
> Signed-off-by: Bjorn Andersson <[email protected]>
> ---
>
> The introduction of 2cd64ae98f35 breaks pretty much all Qualcomm boards and
> grepping the DT tree indicates that other vendors will have the same problem.
>
> In addition to this the am335x-* boards will also needs "[NC]", "[ethernet]",
> "[emmc"], "[i2c0]", "[SYSBOOT]" and "[JTAG]" added to this list to allow
> booting v5.11 with the past and present dtb/dts files.
>
> drivers/gpio/gpiolib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index b3340ba68471..407ba79ae571 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -302,7 +302,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
> struct gpio_device *gdev;
> unsigned long flags;
>
> - if (!name)
> + if (!name || !strcmp(name, "") || !strcmp(name, "NC"))
> return NULL;
>
> spin_lock_irqsave(&gpio_lock, flags);
> --
> 2.29.2
>
I have a bad feeling about this. This opens the door for all kinds of
exceptions: "N/A", "none" etc. Depending on whose boards are getting
broken.
If non-uniqueness of names is needed then let's better revert 2cd64ae98f35.
Bartosz
On Tue 15 Dec 11:42 CST 2020, Bartosz Golaszewski wrote:
> On Tue, Dec 15, 2020 at 6:02 PM Bjorn Andersson
> <[email protected]> wrote:
> >
> > Not all GPIO pins are exposed to the world and this is typically
> > described by not giving these lines particular names, commonly "" or
> > "NC".
> >
> > With the recent introduction of '2cd64ae98f35 ("gpiolib: Disallow
> > identical line names in the same chip")' any gpiochip with multiple such
> > pins will refuse to probe.
> >
> > Fix this by treating "" and "NC" as "no name specified" in
> > gpio_name_to_desc()
> >
> > Fixes: 2cd64ae98f35 ("gpiolib: Disallow identical line names in the same chip")
> > Signed-off-by: Bjorn Andersson <[email protected]>
> > ---
> >
> > The introduction of 2cd64ae98f35 breaks pretty much all Qualcomm boards and
> > grepping the DT tree indicates that other vendors will have the same problem.
> >
> > In addition to this the am335x-* boards will also needs "[NC]", "[ethernet]",
> > "[emmc"], "[i2c0]", "[SYSBOOT]" and "[JTAG]" added to this list to allow
> > booting v5.11 with the past and present dtb/dts files.
> >
> > drivers/gpio/gpiolib.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index b3340ba68471..407ba79ae571 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -302,7 +302,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)
> > struct gpio_device *gdev;
> > unsigned long flags;
> >
> > - if (!name)
> > + if (!name || !strcmp(name, "") || !strcmp(name, "NC"))
> > return NULL;
> >
> > spin_lock_irqsave(&gpio_lock, flags);
> > --
> > 2.29.2
> >
>
> I have a bad feeling about this. This opens the door for all kinds of
> exceptions: "N/A", "none" etc. Depending on whose boards are getting
> broken.
>
> If non-uniqueness of names is needed then let's better revert 2cd64ae98f35.
>
I like the intent of 2cd64ae98f35, but even if we decide what the
"unconnected" name should be we have a slew of boards that won't boot
v5.11-rc1 (or with any pre-v5.11 DTBs).
As such I think we need to revert the "return -EEXIST" part of the
patch.
Looking forward perhaps we should define "" to be the "not a gpio"-name,
revise my patch and fix up the DTs accordingly? And keep the dev_err()
as it currently is?
Regards,
Bjorn