| Message ID | 1437199327-4410-1-git-send-email-dirk.behme@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 18.07.2015 08:02, Dirk Behme wrote: > I've been searching for any documentation of 'the active-low property of a GPIO' > already mentioned in this documenation. But couldn't find any. Add it. > > Sigend-off-by: Dirk Behme <dirk.behme@gmail.com> > Acked-by: Alexandre Courbot <acourbot@nvidia.com> > --- > Changes in v2: Incorporate the review comments from Alexandre. > > Documentation/gpio/consumer.txt | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt > index 75542b9..df7c51a 100644 > --- a/Documentation/gpio/consumer.txt > +++ b/Documentation/gpio/consumer.txt > @@ -237,6 +237,39 @@ Note that these functions should only be used with great moderation ; a driver > should not have to care about the physical line level. > > > +The active-low property > +----------------------- > + > +As a driver should not have to care about the physical line level, all of the > +gpiod_set_value_xxx() or gpiod_set_array_value_xxx() functions operate with > +the *logical* value. With this they take the active-low property into account. > +This does mean that they check whether the GPIO is configured to be active-low. > +And if so, they manipulate the passed value before the physical line level is > +driven. > + > +With this, all the gpiod_set_(array)_value_xxx() functions interpret the parameter > +"value" as "active" ("1") or "inactive" ("0"). The physical line level will be > +driven accordingly. > + > +As an example, if the active-low poperty for a dedicated GPIO is set, and the > +gpiod_set_(array)_value_xxx() passes "active" ("1"), the physical line level will be > +driven low. > + > +To summarize: > + > +Function (example) active-low proporty physical line > +gpiod_set_raw_value(desc, 0); don't care low > +gpiod_set_raw_value(desc, 1); don't care high > +gpiod_set_value(desc, 0); default (active-high) low > +gpiod_set_value(desc, 1); default (active-high) high > +gpiod_set_value(desc, 0); active-low high > +gpiod_set_value(desc, 1); active-low low > + > +Please note again that the set_raw/get_raw functions should be avoided as much > +as possible, especially by drivers which should not care about the actual physical > +line level and worry about the logical value instead. > + > + > Set multiple GPIO outputs with a single function call > ----------------------------------------------------- > The following functions set the output values of an array of GPIOs: Any further comments on this? Could this be applied? Dirk -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/15/2015 02:46 PM, Dirk Behme wrote: > On 18.07.2015 08:02, Dirk Behme wrote: >> I've been searching for any documentation of 'the active-low property >> of a GPIO' >> already mentioned in this documenation. But couldn't find any. Add it. >> >> Sigend-off-by: Dirk Behme <dirk.behme@gmail.com> >> Acked-by: Alexandre Courbot <acourbot@nvidia.com> >> --- >> Changes in v2: Incorporate the review comments from Alexandre. >> >> Documentation/gpio/consumer.txt | 33 +++++++++++++++++++++++++++++++++ >> 1 file changed, 33 insertions(+) >> >> diff --git a/Documentation/gpio/consumer.txt >> b/Documentation/gpio/consumer.txt >> index 75542b9..df7c51a 100644 >> --- a/Documentation/gpio/consumer.txt >> +++ b/Documentation/gpio/consumer.txt >> @@ -237,6 +237,39 @@ Note that these functions should only be used >> with great moderation ; a driver >> should not have to care about the physical line level. >> >> >> +The active-low property >> +----------------------- >> + >> +As a driver should not have to care about the physical line level, >> all of the >> +gpiod_set_value_xxx() or gpiod_set_array_value_xxx() functions >> operate with >> +the *logical* value. With this they take the active-low property into >> account. >> +This does mean that they check whether the GPIO is configured to be >> active-low. >> +And if so, they manipulate the passed value before the physical line >> level is >> +driven. >> + >> +With this, all the gpiod_set_(array)_value_xxx() functions interpret >> the parameter >> +"value" as "active" ("1") or "inactive" ("0"). The physical line >> level will be >> +driven accordingly. >> + >> +As an example, if the active-low poperty for a dedicated GPIO is set, >> and the >> +gpiod_set_(array)_value_xxx() passes "active" ("1"), the physical >> line level will be >> +driven low. >> + >> +To summarize: >> + >> +Function (example) active-low proporty physical line >> +gpiod_set_raw_value(desc, 0); don't care low >> +gpiod_set_raw_value(desc, 1); don't care high >> +gpiod_set_value(desc, 0); default (active-high) low >> +gpiod_set_value(desc, 1); default (active-high) high >> +gpiod_set_value(desc, 0); active-low high >> +gpiod_set_value(desc, 1); active-low low >> + >> +Please note again that the set_raw/get_raw functions should be >> avoided as much >> +as possible, especially by drivers which should not care about the >> actual physical >> +line level and worry about the logical value instead. >> + >> + >> Set multiple GPIO outputs with a single function call >> ----------------------------------------------------- >> The following functions set the output values of an array of GPIOs: > > > Any further comments on this? Could this be applied? I am ok with it - Linus? -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Aug 17, 2015 at 12:01:10PM +0900, Alexandre Courbot wrote: > On 08/15/2015 02:46 PM, Dirk Behme wrote: > >On 18.07.2015 08:02, Dirk Behme wrote: > >>I've been searching for any documentation of 'the active-low property > >>of a GPIO' > >>already mentioned in this documenation. But couldn't find any. Add it. > >> > >>Sigend-off-by: Dirk Behme <dirk.behme@gmail.com> > >>Acked-by: Alexandre Courbot <acourbot@nvidia.com> > >>--- > >>Changes in v2: Incorporate the review comments from Alexandre. > >> > >> Documentation/gpio/consumer.txt | 33 +++++++++++++++++++++++++++++++++ > >> 1 file changed, 33 insertions(+) > >> > >>diff --git a/Documentation/gpio/consumer.txt > >>b/Documentation/gpio/consumer.txt > >>index 75542b9..df7c51a 100644 > >>--- a/Documentation/gpio/consumer.txt > >>+++ b/Documentation/gpio/consumer.txt > >>@@ -237,6 +237,39 @@ Note that these functions should only be used > >>with great moderation ; a driver > >> should not have to care about the physical line level. > >> > >> > >>+The active-low property > >>+----------------------- > >>+ > >>+As a driver should not have to care about the physical line level, > >>all of the > >>+gpiod_set_value_xxx() or gpiod_set_array_value_xxx() functions > >>operate with > >>+the *logical* value. With this they take the active-low property into > >>account. > >>+This does mean that they check whether the GPIO is configured to be > >>active-low. > >>+And if so, they manipulate the passed value before the physical line > >>level is > >>+driven. > >>+ > >>+With this, all the gpiod_set_(array)_value_xxx() functions interpret > >>the parameter > >>+"value" as "active" ("1") or "inactive" ("0"). The physical line > >>level will be > >>+driven accordingly. > >>+ Property is misspelled here. poperty > >>+As an example, if the active-low poperty for a dedicated GPIO is set, > >>and the > >>+gpiod_set_(array)_value_xxx() passes "active" ("1"), the physical > >>line level will be > >>+driven low. > >>+ > >>+To summarize: > >>+ Property is also spelled wrong here too. proporty > >>+Function (example) active-low proporty physical line > >>+gpiod_set_raw_value(desc, 0); don't care low > >>+gpiod_set_raw_value(desc, 1); don't care high > >>+gpiod_set_value(desc, 0); default (active-high) low > >>+gpiod_set_value(desc, 1); default (active-high) high > >>+gpiod_set_value(desc, 0); active-low high > >>+gpiod_set_value(desc, 1); active-low low > >>+ > >>+Please note again that the set_raw/get_raw functions should be > >>avoided as much > >>+as possible, especially by drivers which should not care about the > >>actual physical > >>+line level and worry about the logical value instead. > >>+ > >>+ > >> Set multiple GPIO outputs with a single function call > >> ----------------------------------------------------- > >> The following functions set the output values of an array of GPIOs: > > > > > >Any further comments on this? Could this be applied? > > I am ok with it - Linus? > -- > To unsubscribe from this list: send the line "unsubscribe linux-gpio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, Jul 18, 2015 at 8:02 AM, Dirk Behme <dirk.behme@gmail.com> wrote: > I've been searching for any documentation of 'the active-low property of a GPIO' > already mentioned in this documenation. But couldn't find any. Add it. > > Sigend-off-by: Dirk Behme <dirk.behme@gmail.com> > Acked-by: Alexandre Courbot <acourbot@nvidia.com> > --- > Changes in v2: Incorporate the review comments from Alexandre. I fixed some spelling and grammar and applied this patch. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt index 75542b9..df7c51a 100644 --- a/Documentation/gpio/consumer.txt +++ b/Documentation/gpio/consumer.txt @@ -237,6 +237,39 @@ Note that these functions should only be used with great moderation ; a driver should not have to care about the physical line level. +The active-low property +----------------------- + +As a driver should not have to care about the physical line level, all of the +gpiod_set_value_xxx() or gpiod_set_array_value_xxx() functions operate with +the *logical* value. With this they take the active-low property into account. +This does mean that they check whether the GPIO is configured to be active-low. +And if so, they manipulate the passed value before the physical line level is +driven. + +With this, all the gpiod_set_(array)_value_xxx() functions interpret the parameter +"value" as "active" ("1") or "inactive" ("0"). The physical line level will be +driven accordingly. + +As an example, if the active-low poperty for a dedicated GPIO is set, and the +gpiod_set_(array)_value_xxx() passes "active" ("1"), the physical line level will be +driven low. + +To summarize: + +Function (example) active-low proporty physical line +gpiod_set_raw_value(desc, 0); don't care low +gpiod_set_raw_value(desc, 1); don't care high +gpiod_set_value(desc, 0); default (active-high) low +gpiod_set_value(desc, 1); default (active-high) high +gpiod_set_value(desc, 0); active-low high +gpiod_set_value(desc, 1); active-low low + +Please note again that the set_raw/get_raw functions should be avoided as much +as possible, especially by drivers which should not care about the actual physical +line level and worry about the logical value instead. + + Set multiple GPIO outputs with a single function call ----------------------------------------------------- The following functions set the output values of an array of GPIOs:
I've been searching for any documentation of 'the active-low property of a GPIO' already mentioned in this documenation. But couldn't find any. Add it. Sigend-off-by: Dirk Behme <dirk.behme@gmail.com> Acked-by: Alexandre Courbot <acourbot@nvidia.com> --- Changes in v2: Incorporate the review comments from Alexandre. Documentation/gpio/consumer.txt | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)