Re: [PATCH V4] i2c: qcom-geni: Avoid extra TX DMA TRE for single read message in GPI mode

[Andi Shyti <andi.shyti@kernel.org>]

Hi Aniket,

On Fri, Apr 10, 2026 at 03:49:49PM +0530, Aniket Randive wrote:
> In GPI mode, the I2C GENI driver programs an extra TX DMA transfer
> descriptor (TRE) on the TX channel when handling a single read message.
> This results in an unintended write phase being issued on the I2C bus,
> even though a read transaction does not require any TX data.
> 
> For a single-byte read, the correct hardware sequence consists of the
> CONFIG and GO commands followed by a single RX DMA TRE. Programming an
> additional TX DMA TRE is redundant, causes unnecessary DMA buffer
> mapping on the TX channel, and may lead to incorrect bus behavior.
> 
> Update the transfer logic to avoid programming a TX DMA TRE for single
> read messages in GPI mode.
> 
> Co-developed-by: Maramaina Naresh <naresh.maramaina@oss.qualcomm.com>
> Signed-off-by: Maramaina Naresh <naresh.maramaina@oss.qualcomm.com>
> Signed-off-by: Aniket Randive <aniket.randive@oss.qualcomm.com>

merged to i2c/i2c-host.

Thank you and thanks Mukesh for the review.

Andi