[PATCH v4 0/5] i3c: introduce and use generic parity helper

[PATCH v4 0/5] i3c: introduce and use generic parity helper

[Wolfram Sang]

Changes since v3:

* updated commit message of patch 4 to state that a bug gets fixed.

All acks from bitmap.h and HWMON maintainers are already included.

Old coverletter follows:

I am currently working on upstreaming another I3C controller driver. As
many others, it needs to ensure odd parity for a dynamically assigned
address. The BSP version of the driver implemented a custom parity
algorithm. Wondering why we don't have a generic helper for this in the
kernel, I found that many I3C controller drivers all implement their
version of handling parity.

So, I sent out an RFC[1] moving the efficient implementation of the
SPD5118 driver to a generic location. The series was well received, but
the path for upstream was not clear. Because I need the implementation
for my I3C controller driver and I3C is a prominent user of this new
function, I got the idea of converting the existing I3C drivers and
resend the series, suggesting this all goes upstream via I3C.

A build-tested branch is here:

git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/i3c/get_parity

Looking forward to comments...

[1] https://lore.kernel.org/all/20241214085833.8695-1-wsa+renesas@sang-engineering.com/



Wolfram Sang (5):
  bitops: add generic parity calculation for u8
  hwmon: (spd5118) Use generic parity calculation
  i3c: dw: use parity8 helper instead of open coding it
  i3c: mipi-i3c-hci: use parity8 helper instead of open coding it
  i3c: cdns: use parity8 helper instead of open coding it

 drivers/hwmon/spd5118.c                  |  8 +-----
 drivers/i3c/master/dw-i3c-master.c       | 14 +++--------
 drivers/i3c/master/i3c-master-cdns.c     |  3 +--
 drivers/i3c/master/mipi-i3c-hci/dat_v1.c | 11 +--------
 include/linux/bitops.h                   | 31 ++++++++++++++++++++++++
 5 files changed, 37 insertions(+), 30 deletions(-)

-- 
2.45.2

[PATCH v4 2/5] hwmon: (spd5118) Use generic parity calculation

[Wolfram Sang]

Make use of the new generic helper for calculating the parity.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
 drivers/hwmon/spd5118.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
index 6cee48a3e5c3..358152868d96 100644
--- a/drivers/hwmon/spd5118.c
+++ b/drivers/hwmon/spd5118.c
@@ -291,12 +291,6 @@ static umode_t spd5118_is_visible(const void *_data, enum hwmon_sensor_types typ
 	}
 }
 
-static inline bool spd5118_parity8(u8 w)
-{
-	w ^= w >> 4;
-	return (0x6996 >> (w & 0xf)) & 1;
-}
-
 /*
  * Bank and vendor id are 8-bit fields with seven data bits and odd parity.
  * Vendor IDs 0 and 0x7f are invalid.
@@ -304,7 +298,7 @@ static inline bool spd5118_parity8(u8 w)
  */
 static bool spd5118_vendor_valid(u8 bank, u8 id)
 {
-	if (!spd5118_parity8(bank) || !spd5118_parity8(id))
+	if (parity8(bank) == 0 || parity8(id) == 0)
 		return false;
 
 	id &= 0x7f;
-- 
2.45.2

Re: [PATCH v4 0/5] i3c: introduce and use generic parity helper

[Wolfram Sang]

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> A build-tested branch is here:

That was locally built. Now, build bot said it is happy, too.


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Re: [PATCH v4 0/5] i3c: introduce and use generic parity helper

[Alexandre Belloni]

On Tue, 07 Jan 2025 10:01:58 +0100, Wolfram Sang wrote:
> Changes since v3:
> 
> * updated commit message of patch 4 to state that a bug gets fixed.
> 
> All acks from bitmap.h and HWMON maintainers are already included.
> 
> Old coverletter follows:
> 
> [...]

Applied, thanks!

[1/5] bitops: add generic parity calculation for u8
      https://git.kernel.org/abelloni/c/c320592f3f2a
[2/5] hwmon: (spd5118) Use generic parity calculation
      https://git.kernel.org/abelloni/c/32a8d362b515
[3/5] i3c: dw: use parity8 helper instead of open coding it
      https://git.kernel.org/abelloni/c/e89cc14e96a9
[4/5] i3c: mipi-i3c-hci: use parity8 helper instead of open coding it
      https://git.kernel.org/abelloni/c/e55905a3f33c
[5/5] i3c: cdns: use parity8 helper instead of open coding it
      https://git.kernel.org/abelloni/c/5e8c732357ce

Best regards,

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com