Re: [PATCH 1/3] net: pse-pd: tps23881: Fix current measurement scaling

Am Mon, 6 Oct 2025 14:50:29 +0200
schrieb Kory Maincent [off-list ref]:

On Sat,  4 Oct 2025 20:03:49 +0200
Thomas Wismer [off-list ref] wrote:

quoted

From: Thomas Wismer <redacted>

The TPS23881 improves on the TPS23880 with current sense resistors
reduced from 255 mOhm to 200 mOhm. This has a direct impact on the
scaling of the current measurement. However, the latest TPS23881
data sheet from May 2023 still shows the scaling of the TPS23880
model.  

Didn't know that. Where did you get that new current step value if
it's not from the datasheet?

The correct current measurement scaling can either be found in the
TPS23881B datasheet revised in May 2025 or computed from the legacy sense
resistor value (255 mOhm / 200 mOhm * 70.19 uA = 89.50 uA). I was able to
verify the corrected scaling using power measurement instruments.

Also as the value reported was wrong maybe we need a fix tag here and
send it to net instead of net-next.

Right. I'll resubmit this patch to net.

quoted

Signed-off-by: Thomas Wismer <redacted>
---
 drivers/net/pse-pd/tps23881.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/pse-pd/tps23881.c

b/drivers/net/pse-pd/tps23881.c index 63f8f43062bc..b724b222ab44
100644 --- a/drivers/net/pse-pd/tps23881.c

+++ b/drivers/net/pse-pd/tps23881.c

@@ -62,7 +62,7 @@
 #define TPS23881_REG_SRAM_DATA	0x61
 
 #define TPS23881_UV_STEP	3662
-#define TPS23881_NA_STEP	70190
+#define TPS23881_NA_STEP	89500
 #define TPS23881_MW_STEP	500
 #define TPS23881_MIN_PI_PW_LIMIT_MW	2000