* [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32
@ 2022-10-20 18:18 Gautam Menghani
2022-10-20 20:15 ` Paulo Miguel Almeida
2022-10-20 20:22 ` Nam Cao
0 siblings, 2 replies; 3+ messages in thread
From: Gautam Menghani @ 2022-10-20 18:18 UTC (permalink / raw)
To: gregkh, paulo.miguel.almeida.rodenas
Cc: Gautam Menghani, linux-staging, linux-kernel
A TODO asks to convert the bit_rate variable to be a u32 so that bit
rates up to 300kbps can be supported as per the spec.
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
---
Please note that this patch is only compile tested.
drivers/staging/pi433/TODO | 2 --
drivers/staging/pi433/pi433_if.h | 4 ++--
drivers/staging/pi433/rf69.c | 2 +-
drivers/staging/pi433/rf69.h | 2 +-
4 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/pi433/TODO b/drivers/staging/pi433/TODO
index 5cf3fd99d521..8530bbe61d70 100644
--- a/drivers/staging/pi433/TODO
+++ b/drivers/staging/pi433/TODO
@@ -1,5 +1,3 @@
* currently the code introduces new IOCTLs. I'm afraid this is a bad idea.
-> Replace this with another interface, hints are welcome!
* Some missing data (marked with ###) needs to be added in the documentation
-* Change (struct pi433_tx_cfg)->bit_rate to be a u32 so that we can support
- bit rates up to 300kbps per the spec.
diff --git a/drivers/staging/pi433/pi433_if.h b/drivers/staging/pi433/pi433_if.h
index 25ee0b77a32c..c958dcfa9f96 100644
--- a/drivers/staging/pi433/pi433_if.h
+++ b/drivers/staging/pi433/pi433_if.h
@@ -51,7 +51,7 @@ enum option_on_off {
#define PI433_TX_CFG_IOCTL_NR 0
struct pi433_tx_cfg {
__u32 frequency;
- __u16 bit_rate;
+ __u32 bit_rate;
__u32 dev_frequency;
enum modulation modulation;
enum mod_shaping mod_shaping;
@@ -99,7 +99,7 @@ struct pi433_tx_cfg {
#define PI433_RX_CFG_IOCTL_NR 1
struct pi433_rx_cfg {
__u32 frequency;
- __u16 bit_rate;
+ __u32 bit_rate;
__u32 dev_frequency;
enum modulation modulation;
diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c
index 8c7fab6a46bb..7e754a3aef5f 100644
--- a/drivers/staging/pi433/rf69.c
+++ b/drivers/staging/pi433/rf69.c
@@ -185,7 +185,7 @@ int rf69_set_modulation_shaping(struct spi_device *spi,
}
}
-int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate)
+int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate)
{
int retval;
u32 bit_rate_reg;
diff --git a/drivers/staging/pi433/rf69.h b/drivers/staging/pi433/rf69.h
index 78fa0b8bab8b..46a1fb2d5329 100644
--- a/drivers/staging/pi433/rf69.h
+++ b/drivers/staging/pi433/rf69.h
@@ -24,7 +24,7 @@ int rf69_set_data_mode(struct spi_device *spi, u8 data_mode);
int rf69_set_modulation(struct spi_device *spi, enum modulation modulation);
int rf69_set_modulation_shaping(struct spi_device *spi,
enum mod_shaping mod_shaping);
-int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate);
+int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate);
int rf69_set_deviation(struct spi_device *spi, u32 deviation);
int rf69_set_frequency(struct spi_device *spi, u32 frequency);
int rf69_enable_amplifier(struct spi_device *spi, u8 amplifier_mask);
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32
2022-10-20 18:18 [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32 Gautam Menghani
@ 2022-10-20 20:15 ` Paulo Miguel Almeida
2022-10-20 20:22 ` Nam Cao
1 sibling, 0 replies; 3+ messages in thread
From: Paulo Miguel Almeida @ 2022-10-20 20:15 UTC (permalink / raw)
To: Gautam Menghani; +Cc: gregkh, linux-staging, linux-kernel
On Thu, Oct 20, 2022 at 11:48:15PM +0530, Gautam Menghani wrote:
> A TODO asks to convert the bit_rate variable to be a u32 so that bit
> rates up to 300kbps can be supported as per the spec.
>
Thanks for sending this patch. Comments added in-line.
> diff --git a/drivers/staging/pi433/pi433_if.h b/drivers/staging/pi433/pi433_if.h
> index 25ee0b77a32c..c958dcfa9f96 100644
> --- a/drivers/staging/pi433/pi433_if.h
> +++ b/drivers/staging/pi433/pi433_if.h
> @@ -51,7 +51,7 @@ enum option_on_off {
> #define PI433_TX_CFG_IOCTL_NR 0
> struct pi433_tx_cfg {
> __u32 frequency;
> - __u16 bit_rate;
> + __u32 bit_rate;
> __u32 dev_frequency;
> enum modulation modulation;
> enum mod_shaping mod_shaping;
> @@ -99,7 +99,7 @@ struct pi433_tx_cfg {
> #define PI433_RX_CFG_IOCTL_NR 1
> struct pi433_rx_cfg {
> __u32 frequency;
> - __u16 bit_rate;
> + __u32 bit_rate;
> __u32 dev_frequency;
>
> enum modulation modulation;
Cutting a long story short, you won't be able to change bit_rate's type before
addressing the fact that both pi433_tx_cfg ans pi433_rx_cfg are part of the UAPI.
Usually there are 2 approaches that most people go for when talking about
changes in drivers:
1) Add changes in a backwards compatible way, so whether users are using the
bitrate member as u32 or u64, it would simply work. But that leads to
sometimes hard-to-read code.... but this is still a card up your sleeve.
One suggestion given by Dan Carpenter was to leave the IOCTL impl alone
and start a sysfs implementation. That way you could have a u64 bit_rate
synthetic file.
https://lore.kernel.org/all/20220119053410.GW1978@kadam/
2) Change the tools that make use of this driver at the same time as you change
the UAPI. This can be tricky. There is a thread I started in the
kernelnewbies mailing list on the subject which I think might be relevant
for you to read.
https://lore.kernel.org/all/YjHvLFSV06w%2FORgV@kroah.com/
Happy coding :-)
Paulo A.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32
2022-10-20 18:18 [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32 Gautam Menghani
2022-10-20 20:15 ` Paulo Miguel Almeida
@ 2022-10-20 20:22 ` Nam Cao
1 sibling, 0 replies; 3+ messages in thread
From: Nam Cao @ 2022-10-20 20:22 UTC (permalink / raw)
To: Gautam Menghani
Cc: gregkh, paulo.miguel.almeida.rodenas, linux-staging, linux-kernel
On Thu, Oct 20, 2022 at 11:48:15PM +0530, Gautam Menghani wrote:
> A TODO asks to convert the bit_rate variable to be a u32 so that bit
> rates up to 300kbps can be supported as per the spec.
>
> Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
> ---
> Please note that this patch is only compile tested.
>
> drivers/staging/pi433/TODO | 2 --
> drivers/staging/pi433/pi433_if.h | 4 ++--
> drivers/staging/pi433/rf69.c | 2 +-
> drivers/staging/pi433/rf69.h | 2 +-
> 4 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/staging/pi433/TODO b/drivers/staging/pi433/TODO
> index 5cf3fd99d521..8530bbe61d70 100644
> --- a/drivers/staging/pi433/TODO
> +++ b/drivers/staging/pi433/TODO
> @@ -1,5 +1,3 @@
> * currently the code introduces new IOCTLs. I'm afraid this is a bad idea.
> -> Replace this with another interface, hints are welcome!
> * Some missing data (marked with ###) needs to be added in the documentation
> -* Change (struct pi433_tx_cfg)->bit_rate to be a u32 so that we can support
> - bit rates up to 300kbps per the spec.
> diff --git a/drivers/staging/pi433/pi433_if.h b/drivers/staging/pi433/pi433_if.h
> index 25ee0b77a32c..c958dcfa9f96 100644
> --- a/drivers/staging/pi433/pi433_if.h
> +++ b/drivers/staging/pi433/pi433_if.h
> @@ -51,7 +51,7 @@ enum option_on_off {
> #define PI433_TX_CFG_IOCTL_NR 0
> struct pi433_tx_cfg {
> __u32 frequency;
> - __u16 bit_rate;
> + __u32 bit_rate;
> __u32 dev_frequency;
> enum modulation modulation;
> enum mod_shaping mod_shaping;
> @@ -99,7 +99,7 @@ struct pi433_tx_cfg {
> #define PI433_RX_CFG_IOCTL_NR 1
> struct pi433_rx_cfg {
> __u32 frequency;
> - __u16 bit_rate;
> + __u32 bit_rate;
> __u32 dev_frequency;
>
> enum modulation modulation;
> diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c
> index 8c7fab6a46bb..7e754a3aef5f 100644
> --- a/drivers/staging/pi433/rf69.c
> +++ b/drivers/staging/pi433/rf69.c
> @@ -185,7 +185,7 @@ int rf69_set_modulation_shaping(struct spi_device *spi,
> }
> }
>
> -int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate)
> +int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate)
> {
> int retval;
> u32 bit_rate_reg;
> diff --git a/drivers/staging/pi433/rf69.h b/drivers/staging/pi433/rf69.h
> index 78fa0b8bab8b..46a1fb2d5329 100644
> --- a/drivers/staging/pi433/rf69.h
> +++ b/drivers/staging/pi433/rf69.h
> @@ -24,7 +24,7 @@ int rf69_set_data_mode(struct spi_device *spi, u8 data_mode);
> int rf69_set_modulation(struct spi_device *spi, enum modulation modulation);
> int rf69_set_modulation_shaping(struct spi_device *spi,
> enum mod_shaping mod_shaping);
> -int rf69_set_bit_rate(struct spi_device *spi, u16 bit_rate);
> +int rf69_set_bit_rate(struct spi_device *spi, u32 bit_rate);
> int rf69_set_deviation(struct spi_device *spi, u32 deviation);
> int rf69_set_frequency(struct spi_device *spi, u32 frequency);
> int rf69_enable_amplifier(struct spi_device *spi, u8 amplifier_mask);
> --
> 2.34.1
>
I sent (almost) the exact same patch a while ago. I received a reply
saying that doing this is not possible. That conversation can still be
found here:
https://lore.kernel.org/linux-staging/20220315180820.7393-1-cvn249@gmail.com/t/#u
Best regards,
Nam
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-10-20 18:18 [PATCH] drivers/staging/pi433: Change data type of bit_rate to be u32 Gautam Menghani
2022-10-20 20:15 ` Paulo Miguel Almeida
2022-10-20 20:22 ` Nam Cao
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