Re: [PATCH v2] i2c: designware: size the RX FIFO threshold to the queued transfer

[Andi Shyti]

Hi Navon,

> please, don't forget to Cc the linux-i2c mailing list.
> 
> On Thu, Oct 08, 2026 at 03:52:31AM +0530, Navon John Lukose wrote:
> > i2c_dw_xfer_msg() leaves DW_IC_RX_TL at the 0 that i2c_dw_configure_mode()
> > writes, so the controller raises RX_FULL once per received byte. Program
> > RX_TL from the reads already queued, capped at half the FIFO until the last
> > message is queued, so there is room for the rest.
> > 
> > On an Arrow Lake-H LPSS core with rx_fifo_depth 32, a 22-byte HID input
> > report costs 2.00 interrupts instead of 21.43, and a 452-byte descriptor
> > 0.14 interrupts per byte instead of 1.64. Polling the touchpad with
> > HIDIOCGINPUT at 142 Hz draws 1.58 W less platform power (psys, 32 paired
> > runs).
> > 
> > Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > Assisted-by: LLM
> > Signed-off-by: Navon John Lukose <navonjohnlukose@xxxxxxxxx>
> 
> pushed to i2c/i2c-2.

sorry, I replied to the wrong email. I meant to reply to this
patch[*] that for some reason I can't find in lore.

Andi

[*] https://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git/commit/?id=bdd0514241466ab1e5acce9f1a1b1daf26bff5a2