linux-kernel - Re: [PATCH] i2c: qcom-geni: Fix GPI DMA buffer sync-back

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Date:   Sun, 07 Aug 2022 15:31:17 +0000
From:   Caleb Connolly <caleb@...nolly.tech>
To:     Robin Reckmann <robin.reckmann@...glemail.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>
Cc:     Robin Reckmann <robin.reckmann@...il.com>,
        linux-arm-msm@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH] i2c: qcom-geni: Fix GPI DMA buffer sync-back



On 07/08/2022 15:04, Robin Reckmann wrote:
> Fix i2c transfers using GPI DMA mode for all message types that do not set
> the I2C_M_DMA_SAFE flag (e.g. SMBus "read byte").
>
> In this case a bounce buffer is returned by i2c_get_dma_safe_msg_buf(),
> and it has to synced back to the message after the transfer is done.
>
> Add missing assignment of dma buffer in geni_i2c_gpi().
>
> Set xferred in i2c_put_dma_safe_msg_buf() to true in case of no error to
> ensure the sync-back of this dma buffer to the message.
Thanks for sending this, it fixes GPI DMA on the PocoPhone F1 and Pixel 3!
>
> Signed-off-by: Robin Reckmann <robin.reckmann@...il.com>Reviewed-by: Caleb Connolly <caleb@...nolly.tech>
> ---
>   drivers/i2c/busses/i2c-qcom-geni.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 6ac402ea58fb..d3541e94794e 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -484,12 +484,12 @@ static void geni_i2c_gpi_unmap(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
>   {
>   	if (tx_buf) {
>   		dma_unmap_single(gi2c->se.dev->parent, tx_addr, msg->len, DMA_TO_DEVICE);
> -		i2c_put_dma_safe_msg_buf(tx_buf, msg, false);
> +		i2c_put_dma_safe_msg_buf(tx_buf, msg, !gi2c->err);
>   	}
>
>   	if (rx_buf) {
>   		dma_unmap_single(gi2c->se.dev->parent, rx_addr, msg->len, DMA_FROM_DEVICE);
> -		i2c_put_dma_safe_msg_buf(rx_buf, msg, false);
> +		i2c_put_dma_safe_msg_buf(rx_buf, msg, !gi2c->err);
>   	}
>   }
>
> @@ -553,6 +553,7 @@ static int geni_i2c_gpi(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
>   	desc->callback_param = gi2c;
>
>   	dmaengine_submit(desc);
> +	*buf = dma_buf;
>   	*dma_addr_p = addr;
>
>   	return 0;
> --
> 2.25.1
>

--
Kind Regards,
Caleb