[PATCH] i2c: qcom-geni: make sure I2C hub controllers can't use SE DMA

[PATCH] i2c: qcom-geni: make sure I2C hub controllers can't use SE DMA

[Neil Armstrong]

The I2C Hub controller is a simpler GENI I2C variant that doesn't
support DMA at all, add a no_dma flag to make sure it nevers selects
the SE DMA mode with mappable 32bytes long transfers.

Fixes: cacd9643eca7 ("i2c: qcom-geni: add support for I2C Master Hub variant")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/i2c/busses/i2c-qcom-geni.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 43fdd89b8beb..bfb352b04902 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -97,6 +97,7 @@ struct geni_i2c_dev {
 	dma_addr_t dma_addr;
 	struct dma_chan *tx_c;
 	struct dma_chan *rx_c;
+	bool no_dma;
 	bool gpi_mode;
 	bool abort_done;
 };
@@ -425,7 +426,7 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 	size_t len = msg->len;
 	struct i2c_msg *cur;
 
-	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
+	dma_buf = gi2c->no_dma ? NULL : i2c_get_dma_safe_msg_buf(msg, 32);
 	if (dma_buf)
 		geni_se_select_mode(se, GENI_SE_DMA);
 	else
@@ -464,7 +465,7 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 	size_t len = msg->len;
 	struct i2c_msg *cur;
 
-	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
+	dma_buf = gi2c->no_dma ? NULL : i2c_get_dma_safe_msg_buf(msg, 32);
 	if (dma_buf)
 		geni_se_select_mode(se, GENI_SE_DMA);
 	else
@@ -880,10 +881,12 @@ static int geni_i2c_probe(struct platform_device *pdev)
 		goto err_resources;
 	}
 
-	if (desc && desc->no_dma_support)
+	if (desc && desc->no_dma_support) {
 		fifo_disable = false;
-	else
+		gi2c->no_dma = true;
+	} else {
 		fifo_disable = readl_relaxed(gi2c->se.base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
+	}
 
 	if (fifo_disable) {
 		/* FIFO is disabled, so we can only use GPI DMA */

---
base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa
change-id: 20251029-topic-sm8x50-geni-i2c-hub-no-dma-8812576a65cb

Best regards,
-- 
Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH] i2c: qcom-geni: make sure I2C hub controllers can't use SE DMA

[Konrad Dybcio]

On 10/29/25 7:07 PM, Neil Armstrong wrote:
> The I2C Hub controller is a simpler GENI I2C variant that doesn't
> support DMA at all, add a no_dma flag to make sure it nevers selects
> the SE DMA mode with mappable 32bytes long transfers.
> 
> Fixes: cacd9643eca7 ("i2c: qcom-geni: add support for I2C Master Hub variant")
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  drivers/i2c/busses/i2c-qcom-geni.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 43fdd89b8beb..bfb352b04902 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -97,6 +97,7 @@ struct geni_i2c_dev {
>  	dma_addr_t dma_addr;
>  	struct dma_chan *tx_c;
>  	struct dma_chan *rx_c;
> +	bool no_dma;
>  	bool gpi_mode;
>  	bool abort_done;
>  };
> @@ -425,7 +426,7 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
>  	size_t len = msg->len;
>  	struct i2c_msg *cur;
>  
> -	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
> +	dma_buf = gi2c->no_dma ? NULL : i2c_get_dma_safe_msg_buf(msg, 32);

Not a huge fan of putting the ternary operator here, but I don't
mind that much either

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

Re: [PATCH] i2c: qcom-geni: make sure I2C hub controllers can't use SE DMA

[Mukesh Savaliya]

On 10/30/2025 2:56 PM, Konrad Dybcio wrote:
> On 10/29/25 7:07 PM, Neil Armstrong wrote:
>> The I2C Hub controller is a simpler GENI I2C variant that doesn't
>> support DMA at all, add a no_dma flag to make sure it nevers selects
>> the SE DMA mode with mappable 32bytes long transfers.
>>
>> Fixes: cacd9643eca7 ("i2c: qcom-geni: add support for I2C Master Hub variant")
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>> ---
>>   drivers/i2c/busses/i2c-qcom-geni.c | 11 +++++++----
>>   1 file changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>> index 43fdd89b8beb..bfb352b04902 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -97,6 +97,7 @@ struct geni_i2c_dev {
>>   	dma_addr_t dma_addr;
>>   	struct dma_chan *tx_c;
>>   	struct dma_chan *rx_c;
>> +	bool no_dma;
>>   	bool gpi_mode;
>>   	bool abort_done;
>>   };
>> @@ -425,7 +426,7 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
>>   	size_t len = msg->len;
>>   	struct i2c_msg *cur;
>>   
>> -	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
>> +	dma_buf = gi2c->no_dma ? NULL : i2c_get_dma_safe_msg_buf(msg, 32);
> 
> Not a huge fan of putting the ternary operator here, but I don't
> mind that much either
> 
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Reviewed-by: Mukesh Kumar Savaliya <mukesh.savaliya@oss.qualcomm.com>>
> Konrad