Hi Dzmitry,
On 1/14/23 20:42, Dzmitry Sankouski wrote:
dev_read_u32 will fail, if linux,code is not found.
We shouldn't fail here, as linux,code is optional, so maybe dev_read_u32_default
with 0 default value, instead of negative error code?
No, 0 is an existing and valid code.
FYI, linux,code is not optional for GPIO buttons in the Linux kernel and
fails the device probing. What would be the usecase for GPIO buttons
without a code?
In the event we really want to allow no linux,cpde for GPIO button:
It's fine if dev_read_u32 fails, you can use the return code as logic on
what to do next.
I believe you need to have a signed variable to store one invalid value
(e.g. -EINVAL or -ENOTSUPP or something like that). You could also have
a boolean stating whether a linux,code was found for this device. You
could also use some pointer to an u32 which would be NULL if not
present, but then you'd have to do memory allocation/freeing.
ср, 11 янв. 2023 г. в 18:48, Quentin Schulz
<quentin.sch...@theobroma-systems.com>:
Hi Dzmitry,
On 1/11/23 11:19, Dzmitry Sankouski wrote:
Linux event code may be used in input devices, using buttons.
Signed-off-by: Dzmitry Sankouski <dsankou...@gmail.com>
---
drivers/button/button-gpio.c | 20 ++++++++++++++++++++
drivers/button/button-uclass.c | 10 ++++++++++
include/button.h | 16 ++++++++++++++++
3 files changed, 46 insertions(+)
diff --git a/drivers/button/button-gpio.c b/drivers/button/button-gpio.c
index dbb000622c..e6eff5c1da 100644
--- a/drivers/button/button-gpio.c
+++ b/drivers/button/button-gpio.c
@@ -13,6 +13,7 @@
struct button_gpio_priv {
struct gpio_desc gpio;
+ u32 linux_code;
};
static enum button_state_t button_gpio_get_state(struct udevice *dev)
@@ -29,10 +30,22 @@ static enum button_state_t button_gpio_get_state(struct
udevice *dev)
return ret ? BUTTON_ON : BUTTON_OFF;
}
+static u32 button_gpio_get_code(struct udevice *dev)
+{
+ struct button_gpio_priv *priv = dev_get_priv(dev);
+ u32 code = priv->linux_code;
+
+ if (!code)
+ return 0;
+
I think we need something better than returning 0 in case there's no
linux,code, since 0 is technically a valid linux,code.
There are multiple ways of doing this, here are the two that comes to my
mind right now.
1) have
int (*get_code)(struct udevice *dev, u32 *code);
instead of
u32 (*get_code)(struct udevice *dev);
and have the function return 0 on success or -EINVAL/-ENOTSUPP/whatever
if linux,code was not set.
2) use a struct
struct res {
int ret;
u32 code;
};
struct res (*get_code)(struct udevice *dev);
instead of
u32 (*get_code)(struct udevice *dev);
and check on res.ret before reading res.code in your framework.
Cheers,
Quentin
+ return code;
+}
+
static int button_gpio_probe(struct udevice *dev)
{
struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev);
struct button_gpio_priv *priv = dev_get_priv(dev);
+ u32 linux_code;
int ret;
/* Ignore the top-level button node */
@@ -43,6 +56,12 @@ static int button_gpio_probe(struct udevice *dev)
if (ret)
return ret;
+ linux_code = dev_read_u32_default(dev, "linux,code", -ENODATA);
+ debug("linux code value: %d, ret: %d", linux_code, ret);
+ if (ret)
+ return ret;
ret is not modified here so it'll always pass even if it fails to parse
dev_read_u32_default.
I believe dev_read_u32_default incorrectly requests an int as last
argument while it's going to fill it with u32 data on success.
dev_read_u8/u16 get this correctly so that might just be an oversight.
Please use dev_read_u32 instead:
ret = dev_read_u32(dev, "linux,code", &priv->linux_code);
debug("linux code value: %d, ret: %d", linux_code, ret);
return ret;
(no need to check the value of ret since it's the same as
if (ret)
return ret;
return 0;
)
Cheers,
Quentin
