| Message ID | 20210708070429.31871-2-sergio.paracuellos@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | gpiolib: convert 'devprop_gpiochip_set_names' to support multiple gpiochip per device | expand |
Hi Sergio, On Thu, Jul 08, 2021 at 09:04:27AM +0200, Sergio Paracuellos wrote: > The default gpiolib-of implementation does not work with the multiple > gpiochip banks per device structure used for example by the gpio-mt7621 > and gpio-brcmstb drivers. To fix these kind of situations driver code > is forced to fill the names to avoid the gpiolib code to set names > repeated along the banks. Instead of continue with that antipattern > fix the gpiolib core function to get expected behaviour for every > single situation adding a field 'offset' in the gpiochip structure. > Doing in this way, we can assume this offset will be zero for normal > driver code where only one gpiochip bank per device is used but > can be set explicitly in those drivers that really need more than > one gpiochip. This is a nice improvement, thanks for putting this together! A few remarks below: > > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com> > --- > drivers/gpio/gpiolib.c | 34 ++++++++++++++++++++++++++++------ > include/linux/gpio/driver.h | 4 ++++ > 2 files changed, 32 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 27c07108496d..f3f45b804542 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -382,11 +382,16 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > if (count < 0) > return 0; > > - if (count > gdev->ngpio) { > - dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", > - count, gdev->ngpio); > - count = gdev->ngpio; > - } > + /* > + * When offset is set in the driver side we assume the driver internally > + * is using more than one gpiochip per the same device. We have to stop > + * setting friendly names if the specified ones with 'gpio-line-names' > + * are less than the offset in the device itself. This means all the > + * lines are not present for every single pin within all the internal > + * gpiochips. > + */ > + if (count <= chip->offset) > + return 0; This case needs a descriptive warning message. Silent failure to assign names here will leave someone confused about what they're doing wrong. > > names = kcalloc(count, sizeof(*names), GFP_KERNEL); > if (!names) > @@ -400,8 +405,25 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > return ret; > } > > + /* > + * When more that one gpiochip per device is used, 'count' can > + * contain at most number gpiochips x chip->ngpio. We have to > + * correctly distribute all defined lines taking into account > + * chip->offset as starting point from where we will assign > + * the names to pins from the 'names' array. Since property > + * 'gpio-line-names' cannot contains gaps, we have to be sure > + * we only assign those pins that really exists since chip->ngpio > + * can be different of the chip->offset. > + */ > + count = (count > chip->offset) ? count - chip->offset : count; > + if (count > chip->ngpio) { In the multiple gpiochip case, if there are 3+ gpiochips this seems like it will yield an invalid warning. For example, if there are 3 gpiochips (banks 0, 1, and 2), and all gpios are given names in gpio-line-names, isn't this condition going to always evaluate to true for bank 1, resulting in an invalid warning? In that case I would think setting count to chip->ngpio is the *expected* behavior. Since that's a "normal" behavior in the multiple gpiochip case, I'm not sure there's a simple way to detect an over-long gpio-line-names here in this function anymore. > + dev_warn(&gdev->dev, "gpio-line-names is length %d but > should be at most length %d", + count, > chip->ngpio); > + count = chip->ngpio; + } + for (i = 0; i < count; i++) > - gdev->descs[i].name = names[i]; + > gdev->descs[i].name = names[chip->offset + i]; > > kfree(names); > > [snip] Best regards, Gregory
Hi Gregory, Thanks for the feedback. On Mon, Jul 19, 2021 at 9:57 AM Gregory Fong <gregory.0xf0@gmail.com> wrote: > > Hi Sergio, > > On Thu, Jul 08, 2021 at 09:04:27AM +0200, Sergio Paracuellos wrote: > > The default gpiolib-of implementation does not work with the multiple > > gpiochip banks per device structure used for example by the gpio-mt7621 > > and gpio-brcmstb drivers. To fix these kind of situations driver code > > is forced to fill the names to avoid the gpiolib code to set names > > repeated along the banks. Instead of continue with that antipattern > > fix the gpiolib core function to get expected behaviour for every > > single situation adding a field 'offset' in the gpiochip structure. > > Doing in this way, we can assume this offset will be zero for normal > > driver code where only one gpiochip bank per device is used but > > can be set explicitly in those drivers that really need more than > > one gpiochip. > > This is a nice improvement, thanks for putting this together! A few > remarks below: > > > > > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com> > > --- > > drivers/gpio/gpiolib.c | 34 ++++++++++++++++++++++++++++------ > > include/linux/gpio/driver.h | 4 ++++ > > 2 files changed, 32 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > index 27c07108496d..f3f45b804542 100644 > > --- a/drivers/gpio/gpiolib.c > > +++ b/drivers/gpio/gpiolib.c > > @@ -382,11 +382,16 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > if (count < 0) > > return 0; > > > > - if (count > gdev->ngpio) { > > - dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", > > - count, gdev->ngpio); > > - count = gdev->ngpio; > > - } > > + /* > > + * When offset is set in the driver side we assume the driver internally > > + * is using more than one gpiochip per the same device. We have to stop > > + * setting friendly names if the specified ones with 'gpio-line-names' > > + * are less than the offset in the device itself. This means all the > > + * lines are not present for every single pin within all the internal > > + * gpiochips. > > + */ > > + if (count <= chip->offset) > > + return 0; > > This case needs a descriptive warning message. Silent failure to assign > names here will leave someone confused about what they're doing wrong. Ok, I will add something like "All line names are not defined for bank X.". Or any other suggestion would be also ok :). > > > > > names = kcalloc(count, sizeof(*names), GFP_KERNEL); > > if (!names) > > @@ -400,8 +405,25 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > return ret; > > } > > > > + /* > > + * When more that one gpiochip per device is used, 'count' can > > + * contain at most number gpiochips x chip->ngpio. We have to > > + * correctly distribute all defined lines taking into account > > + * chip->offset as starting point from where we will assign > > + * the names to pins from the 'names' array. Since property > > + * 'gpio-line-names' cannot contains gaps, we have to be sure > > + * we only assign those pins that really exists since chip->ngpio > > + * can be different of the chip->offset. > > + */ > > + count = (count > chip->offset) ? count - chip->offset : count; > > + if (count > chip->ngpio) { > > In the multiple gpiochip case, if there are 3+ gpiochips this seems like > it will yield an invalid warning. For example, if there are 3 gpiochips > (banks 0, 1, and 2), and all gpios are given names in gpio-line-names, > isn't this condition going to always evaluate to true for bank 1, > resulting in an invalid warning? In that case I would think setting > count to chip->ngpio is the *expected* behavior. > > Since that's a "normal" behavior in the multiple gpiochip case, I'm not > sure there's a simple way to detect an over-long gpio-line-names here > in this function anymore. Yes, in case of multiple chips with all lines names defined this warning will be displayed but I wanted to maintain the warning for normal cases and I was not able to find an easy way of distinc that cases with those having multiple gpiochips internally. So I ended up in "ok, will be displayed for those special cases and interpreted as we are just assigning names within an offset along the gpiochips in the device.". Any other suggestion of course is always welcome :) Thanks, Sergio Paracuellos > > > + dev_warn(&gdev->dev, "gpio-line-names is length %d but > > should be at most length %d", + count, > > chip->ngpio); > > + count = chip->ngpio; + } + for (i = 0; i < count; i++) > > - gdev->descs[i].name = names[i]; + > > gdev->descs[i].name = names[chip->offset + i]; > > > > kfree(names); > > > > [snip] > > Best regards, > Gregory
On Mon, Jul 19, 2021 at 1:31 AM Sergio Paracuellos <sergio.paracuellos@gmail.com> wrote: > On Mon, Jul 19, 2021 at 9:57 AM Gregory Fong <gregory.0xf0@gmail.com> wrote: > > On Thu, Jul 08, 2021 at 09:04:27AM +0200, Sergio Paracuellos wrote: > [snip] > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > > index 27c07108496d..f3f45b804542 100644 > > > --- a/drivers/gpio/gpiolib.c > > > +++ b/drivers/gpio/gpiolib.c > > > @@ -382,11 +382,16 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > > if (count < 0) > > > return 0; > > > > > > - if (count > gdev->ngpio) { > > > - dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", > > > - count, gdev->ngpio); > > > - count = gdev->ngpio; > > > - } > > > + /* > > > + * When offset is set in the driver side we assume the driver internally > > > + * is using more than one gpiochip per the same device. We have to stop > > > + * setting friendly names if the specified ones with 'gpio-line-names' > > > + * are less than the offset in the device itself. This means all the > > > + * lines are not present for every single pin within all the internal > > > + * gpiochips. > > > + */ > > > + if (count <= chip->offset) > > > + return 0; > > > > This case needs a descriptive warning message. Silent failure to assign > > names here will leave someone confused about what they're doing wrong. > > Ok, I will add something like "All line names are not defined for bank > X.". Or any other suggestion would be also ok :). I'd like this to name the gpio-line-names property like the other warning does. Not sure there's a good way to generically determine what the bank number is, since some driver might not populate at regular offsets. We do have the count and offset available, so maybe something like "gpio-line-names too short (length <count>), cannot map names for the gpiochip at offset <offset>"? > > > > > > > > > names = kcalloc(count, sizeof(*names), GFP_KERNEL); > > > if (!names) > > > @@ -400,8 +405,25 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > > return ret; > > > } > > > > > > + /* > > > + * When more that one gpiochip per device is used, 'count' can > > > + * contain at most number gpiochips x chip->ngpio. We have to > > > + * correctly distribute all defined lines taking into account > > > + * chip->offset as starting point from where we will assign > > > + * the names to pins from the 'names' array. Since property > > > + * 'gpio-line-names' cannot contains gaps, we have to be sure > > > + * we only assign those pins that really exists since chip->ngpio > > > + * can be different of the chip->offset. > > > + */ > > > + count = (count > chip->offset) ? count - chip->offset : count; > > > + if (count > chip->ngpio) { > > > > In the multiple gpiochip case, if there are 3+ gpiochips this seems like > > it will yield an invalid warning. For example, if there are 3 gpiochips > > (banks 0, 1, and 2), and all gpios are given names in gpio-line-names, > > isn't this condition going to always evaluate to true for bank 1, > > resulting in an invalid warning? In that case I would think setting > > count to chip->ngpio is the *expected* behavior. > > > > Since that's a "normal" behavior in the multiple gpiochip case, I'm not > > sure there's a simple way to detect an over-long gpio-line-names here > > in this function anymore. > > Yes, in case of multiple chips with all lines names defined this > warning will be displayed but I wanted to maintain the warning for > normal cases and I was not able to find an easy way of distinc that > cases with those having multiple gpiochips internally. So I ended up > in "ok, will be displayed for those special cases and interpreted as > we are just assigning names within an offset along the gpiochips in > the device.". Any other suggestion of course is always welcome :) There are millions of parts with this gpio hardware in the wild; I'd much prefer we didn't issue a warning for every chip using it. If there is a good way to detect the multiple gpiochip case, then that could be used to determine whether to issue the warning. Otherwise, it seems like it would be better to remove the warning altogether. Best regards, Gregory
Hi Gregory, On Tue, Jul 27, 2021 at 9:39 AM Gregory Fong <gregory.0xf0@gmail.com> wrote: > > On Mon, Jul 19, 2021 at 1:31 AM Sergio Paracuellos > <sergio.paracuellos@gmail.com> wrote: > > On Mon, Jul 19, 2021 at 9:57 AM Gregory Fong <gregory.0xf0@gmail.com> wrote: > > > On Thu, Jul 08, 2021 at 09:04:27AM +0200, Sergio Paracuellos wrote: > > [snip] > > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > > > index 27c07108496d..f3f45b804542 100644 > > > > --- a/drivers/gpio/gpiolib.c > > > > +++ b/drivers/gpio/gpiolib.c > > > > @@ -382,11 +382,16 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > > > if (count < 0) > > > > return 0; > > > > > > > > - if (count > gdev->ngpio) { > > > > - dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", > > > > - count, gdev->ngpio); > > > > - count = gdev->ngpio; > > > > - } > > > > + /* > > > > + * When offset is set in the driver side we assume the driver internally > > > > + * is using more than one gpiochip per the same device. We have to stop > > > > + * setting friendly names if the specified ones with 'gpio-line-names' > > > > + * are less than the offset in the device itself. This means all the > > > > + * lines are not present for every single pin within all the internal > > > > + * gpiochips. > > > > + */ > > > > + if (count <= chip->offset) > > > > + return 0; > > > > > > This case needs a descriptive warning message. Silent failure to assign > > > names here will leave someone confused about what they're doing wrong. > > > > Ok, I will add something like "All line names are not defined for bank > > X.". Or any other suggestion would be also ok :). > > I'd like this to name the gpio-line-names property like the other > warning does. Not sure there's a good way to generically determine > what the bank number is, since some driver might not populate at > regular offsets. > > We do have the count and offset available, so maybe something like > "gpio-line-names too short (length <count>), cannot map names for the > gpiochip at offset <offset>"? Ok, sounds ok to me to have this warning in this way, thanks. > > > > > > > > > > > > > > names = kcalloc(count, sizeof(*names), GFP_KERNEL); > > > > if (!names) > > > > @@ -400,8 +405,25 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) > > > > return ret; > > > > } > > > > > > > > + /* > > > > + * When more that one gpiochip per device is used, 'count' can > > > > + * contain at most number gpiochips x chip->ngpio. We have to > > > > + * correctly distribute all defined lines taking into account > > > > + * chip->offset as starting point from where we will assign > > > > + * the names to pins from the 'names' array. Since property > > > > + * 'gpio-line-names' cannot contains gaps, we have to be sure > > > > + * we only assign those pins that really exists since chip->ngpio > > > > + * can be different of the chip->offset. > > > > + */ > > > > + count = (count > chip->offset) ? count - chip->offset : count; > > > > + if (count > chip->ngpio) { > > > > > > In the multiple gpiochip case, if there are 3+ gpiochips this seems like > > > it will yield an invalid warning. For example, if there are 3 gpiochips > > > (banks 0, 1, and 2), and all gpios are given names in gpio-line-names, > > > isn't this condition going to always evaluate to true for bank 1, > > > resulting in an invalid warning? In that case I would think setting > > > count to chip->ngpio is the *expected* behavior. > > > > > > Since that's a "normal" behavior in the multiple gpiochip case, I'm not > > > sure there's a simple way to detect an over-long gpio-line-names here > > > in this function anymore. > > > > Yes, in case of multiple chips with all lines names defined this > > warning will be displayed but I wanted to maintain the warning for > > normal cases and I was not able to find an easy way of distinc that > > cases with those having multiple gpiochips internally. So I ended up > > in "ok, will be displayed for those special cases and interpreted as > > we are just assigning names within an offset along the gpiochips in > > the device.". Any other suggestion of course is always welcome :) > > There are millions of parts with this gpio hardware in the wild; I'd > much prefer we didn't issue a warning for every chip using it. > > If there is a good way to detect the multiple gpiochip case, then that > could be used to determine whether to issue the warning. Otherwise, > it seems like it would be better to remove the warning altogether. I think since this might be kind of "normal scenery" now, and there is not an easy way to distinguish between normal and special cases (it is?) warning can be safely removed. > > Best regards, > Gregory Best regards, Sergio Paracuellos
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 27c07108496d..f3f45b804542 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -382,11 +382,16 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) if (count < 0) return 0; - if (count > gdev->ngpio) { - dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", - count, gdev->ngpio); - count = gdev->ngpio; - } + /* + * When offset is set in the driver side we assume the driver internally + * is using more than one gpiochip per the same device. We have to stop + * setting friendly names if the specified ones with 'gpio-line-names' + * are less than the offset in the device itself. This means all the + * lines are not present for every single pin within all the internal + * gpiochips. + */ + if (count <= chip->offset) + return 0; names = kcalloc(count, sizeof(*names), GFP_KERNEL); if (!names) @@ -400,8 +405,25 @@ static int devprop_gpiochip_set_names(struct gpio_chip *chip) return ret; } + /* + * When more that one gpiochip per device is used, 'count' can + * contain at most number gpiochips x chip->ngpio. We have to + * correctly distribute all defined lines taking into account + * chip->offset as starting point from where we will assign + * the names to pins from the 'names' array. Since property + * 'gpio-line-names' cannot contains gaps, we have to be sure + * we only assign those pins that really exists since chip->ngpio + * can be different of the chip->offset. + */ + count = (count > chip->offset) ? count - chip->offset : count; + if (count > chip->ngpio) { + dev_warn(&gdev->dev, "gpio-line-names is length %d but should be at most length %d", + count, chip->ngpio); + count = chip->ngpio; + } + for (i = 0; i < count; i++) - gdev->descs[i].name = names[i]; + gdev->descs[i].name = names[chip->offset + i]; kfree(names); diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 3a268781fcec..a0f9901dcae6 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -312,6 +312,9 @@ struct gpio_irq_chip { * get rid of the static GPIO number space in the long run. * @ngpio: the number of GPIOs handled by this controller; the last GPIO * handled is (base + ngpio - 1). + * @offset: when multiple gpio chips belong to the same device this + * can be used as offset within the device so friendly names can + * be properly assigned. * @names: if set, must be an array of strings to use as alternative * names for the GPIOs in this chip. Any entry in the array * may be NULL if there is no alias for the GPIO, however the @@ -398,6 +401,7 @@ struct gpio_chip { int base; u16 ngpio; + u16 offset; const char *const *names; bool can_sleep;
The default gpiolib-of implementation does not work with the multiple gpiochip banks per device structure used for example by the gpio-mt7621 and gpio-brcmstb drivers. To fix these kind of situations driver code is forced to fill the names to avoid the gpiolib code to set names repeated along the banks. Instead of continue with that antipattern fix the gpiolib core function to get expected behaviour for every single situation adding a field 'offset' in the gpiochip structure. Doing in this way, we can assume this offset will be zero for normal driver code where only one gpiochip bank per device is used but can be set explicitly in those drivers that really need more than one gpiochip. Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com> --- drivers/gpio/gpiolib.c | 34 ++++++++++++++++++++++++++++------ include/linux/gpio/driver.h | 4 ++++ 2 files changed, 32 insertions(+), 6 deletions(-)