Re: [PATCH v9 2/9] Input: goodix - reset device at init
On Tue, Oct 13, 2015 at 08:54:12AM +, Tirdea, Irina wrote: > > > I did not use devm_gpiod_get_optional() in order to ignore more errors > > > than -ENOENT. This is needed because the ACPI gpio core will fall back > > > to indexed gpios if named gpios are not found. In the common case of > > > having 2 indexed gpio pins declared in the ACPI table, the first > > > devm_gpiod_get() will successfully get indexed gpio pin 0 and the > > > second devm_gpiod_get() will try to get the same gpio pin 0 and return > > > -EBUSY. Considering this, I thought it is better to just ignore all > > > errors in > > > order not to break any platforms currently using this driver. > > > > This seems like issue with ACPI gpio lookup implementation. If I am > > requesting named gpio and it is not present then I definitely do not > > need to be returned some random gpio. Doing so breaks all other drivers > > that use several names to retrieve GPIOs. We basically can't trust GPIO > > API on ACPI systems. > > > > I'm not sure there is a way to avoid fall back to indexed gpios when > requesting > named gpios. > Adding Mika to this thread as he might help answer this. Before ACPI 5.1 _DSD device properties were introduced all we had was an array of GPIOs returned by _CRS ACPI method. Ordering of those GPIOs could change from one vendor to another :-( We can (and do) use acpi_dev_add_driver_gpios() to pass correct mappings where _DSD is not present based on the device ACPI ID for instance. Not all drivers do that, though. I would like to get rid of the fallback completely at some point. We have had already problems with the API because then some ACPI only drivers did this: reset_gpio = gpiod_get_index(dev, NULL, 0); power_gpio = gpiod_get_index(dev, NULL, 1); which might not do what is expected on DT systems. That's why acpi_dev_add_driver_gpios() was added in the first place IIRC. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v9 2/9] Input: goodix - reset device at init
On Tue, Oct 13, 2015 at 11:23:03PM -0700, Dmitry Torokhov wrote: > I understand why one might use acpi_dev_add_driver_gpios() to augment > data in ACPI, however here we have completely different issue: driver > that expects named gpios gets returned gpio that has nothing to do with > what it requested, because gpiolib acpi code always falls back to > unnamed gpio if it does not find named gpio. That can be acceptable if > driver uses the same con_id for all requests to gpiolib, but is not > working when driver supplies different con_ids. Right, the ACPI fallback ignores con_id completely and uses only the index. AFAIK there is only one driver using ACPI _CRS index method: sdhci-[acpi|pci].c. If we can convert that to use acpi_dev_add_driver_gpios() to feed names for card detection GPIOs, I think we can remove the fallback alltogether in favor of named GPIOs for ACPI. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v9 2/9] Input: goodix - reset device at init
On Wed, Oct 14, 2015 at 02:18:20PM +0300, mika.westerb...@linux.intel.com wrote: > On Tue, Oct 13, 2015 at 11:23:03PM -0700, Dmitry Torokhov wrote: > > I understand why one might use acpi_dev_add_driver_gpios() to augment > > data in ACPI, however here we have completely different issue: driver > > that expects named gpios gets returned gpio that has nothing to do with > > what it requested, because gpiolib acpi code always falls back to > > unnamed gpio if it does not find named gpio. That can be acceptable if > > driver uses the same con_id for all requests to gpiolib, but is not > > working when driver supplies different con_ids. > > Right, the ACPI fallback ignores con_id completely and uses only the > index. > > AFAIK there is only one driver using ACPI _CRS index method: > sdhci-[acpi|pci].c. If we can convert that to use acpi_dev_add_driver_gpios() > to feed names for card detection GPIOs, I think we can remove the > fallback alltogether in favor of named GPIOs for ACPI. Nah, there seems to be several drivers relying on this already :-/ -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v9 2/9] Input: goodix - reset device at init
On Mon, Oct 19, 2015 at 02:32:24PM +, Tirdea, Irina wrote:
>
>
> > -Original Message-
> > From: linux-input-ow...@vger.kernel.org
> > [mailto:linux-input-ow...@vger.kernel.org] On Behalf Of
> > mika.westerb...@linux.intel.com
> > Sent: 14 October, 2015 16:44
> > To: Dmitry Torokhov
> > Cc: Tirdea, Irina; Bastien Nocera; Aleksei Mamlin; Karsten Merker;
> > linux-input@vger.kernel.org; Mark Rutland; Purdila, Octavian; linux-
> > ker...@vger.kernel.org; devicet...@vger.kernel.org
> > Subject: Re: [PATCH v9 2/9] Input: goodix - reset device at init
> >
> > On Wed, Oct 14, 2015 at 02:18:20PM +0300, mika.westerb...@linux.intel.com
> > wrote:
> > > On Tue, Oct 13, 2015 at 11:23:03PM -0700, Dmitry Torokhov wrote:
> > > > I understand why one might use acpi_dev_add_driver_gpios() to augment
> > > > data in ACPI, however here we have completely different issue: driver
> > > > that expects named gpios gets returned gpio that has nothing to do with
> > > > what it requested, because gpiolib acpi code always falls back to
> > > > unnamed gpio if it does not find named gpio. That can be acceptable if
> > > > driver uses the same con_id for all requests to gpiolib, but is not
> > > > working when driver supplies different con_ids.
> > >
> > > Right, the ACPI fallback ignores con_id completely and uses only the
> > > index.
> > >
> > > AFAIK there is only one driver using ACPI _CRS index method:
> > > sdhci-[acpi|pci].c. If we can convert that to use
> > > acpi_dev_add_driver_gpios()
> > > to feed names for card detection GPIOs, I think we can remove the
> > > fallback alltogether in favor of named GPIOs for ACPI.
> >
> > Nah, there seems to be several drivers relying on this already :-/
>
> Would it be possible to add an optional parameter to the GPIO API
> to specify whether we want to fall back to indexed GPIOs for ACPI?
I don't think it's a good idea to add ACPI specifics to generic APIs.
I went through ACPI enabled drivers calling GPIO APIs and majority of
them are doing this:
static int stk8312_gpio_probe(struct i2c_client *client)
{
struct device *dev;
struct gpio_desc *gpio;
int ret;
if (!client)
return -EINVAL;
dev = &client->dev;
/* data ready gpio interrupt pin */
gpio = devm_gpiod_get_index(dev, STK8312_GPIO, 0, GPIOD_IN);
if (IS_ERR(gpio)) {
dev_err(dev, "acpi gpio get index failed\n");
return PTR_ERR(gpio);
}
ret = gpiod_to_irq(gpio);
dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
return ret;
}
We can drop all this because I2C core already handles GpioInt -> interrupt
number translation.
Few drivers are doing something more complex but I think we can still convert
them to use acpi_dev_add_driver_gpios() and eventually get rid of the whole
_CRS index lookup.
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Re: [PATCH v9 2/9] Input: goodix - reset device at init
On Fri, Oct 30, 2015 at 09:33:28AM -0700, Dmitry Torokhov wrote:
> cpi_dev_add_driver_gpios() does not really help with generic drivers
> (unless we keep adding more and more board specific data to them). How
> about we keep track of names used and only allow conversion for the
> first name used, like in the patch below?
That works but it misses one case: When you have optional GPIOs and not
all of them are provided. Currently it ends up the same situation
returning the same GPIO.
I've commented below how we could handle that case as well.
> --
> Dmitry
>
> gpiolib: tighten up ACPI legacy gpio lookups
>
> From: Dmitry Torokhov
>
> We should not fall back to the legacy unnamed gpio lookup style if the
> driver requests gpios with different names, because we'll give out the same
> gpio twice. Let's keep track of the names that were used for the device and
> only do the fallback for the first name used.
>
> Signed-off-by: Dmitry Torokhov
> ---
> drivers/gpio/gpiolib.c | 42 +-
> 1 file changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 5db3445..4ae5447 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1738,6 +1738,45 @@ static struct gpio_desc *of_find_gpio(struct device
> *dev, const char *con_id,
> return desc;
> }
>
> +struct acpi_gpio_lookup {
> + struct list_head node;
> + struct device *dev;
> + const char *con_id;
> +};
> +
> +static DEFINE_MUTEX(acpi_gpio_lookup_lock);
> +static LIST_HEAD(acpi_gpio_lookup_list);
> +
> +static bool acpi_can_fallback_crs(struct device *dev, const char *con_id)
> +{
> + struct acpi_gpio_lookup *l, *lookup = NULL;
I'm thinking if we here do
struct acpi_device *adev = ACPI_COMPANION(dev);
/* Never fallback if the device has properties */
if (adev->data.properties || adev->driver_gpios)
return false;
> +
> + mutex_lock(&acpi_gpio_lookup_lock);
> +
> + list_for_each_entry(l, &acpi_gpio_lookup_list, node) {
> + if (l->dev == dev) {
> + lookup = l;
> + break;
> + }
> + }
> +
> + if (!lookup) {
> + lookup = kmalloc(sizeof(*lookup), GFP_KERNEL);
> + if (lookup) {
> + lookup->dev = dev;
> + lookup->con_id = con_id;
> + list_add_tail(&lookup->node, &acpi_gpio_lookup_list);
> + }
> + }
> +
> + mutex_lock(&acpi_gpio_lookup_lock);
> +
> + return lookup &&
> + ((!lookup->con_id && !con_id) ||
> + (lookup->con_id && con_id &&
> + strcmp(lookup->con_id, con_id) == 0));
> +}
> +
> static struct gpio_desc *acpi_find_gpio(struct device *dev, const char
> *con_id,
> unsigned int idx,
> enum gpio_lookup_flags *flags)
> @@ -1765,7 +1804,8 @@ static struct gpio_desc *acpi_find_gpio(struct device
> *dev, const char *con_id,
>
> /* Then from plain _CRS GPIOs */
> if (IS_ERR(desc)) {
> - desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
> + if (acpi_can_fallback_crs(dev, con_id))
> + desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
and here we could do
if (!acpi_can_fallback_crs(dev, con_id))
return ERR_PTR(-ENOENT);
desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);
So instead return -ENOENT so that gpiod_get_index_optional() handles the
missing optional GPIO properly.
> if (IS_ERR(desc))
> return desc;
> }
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