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

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Message-ID: <77031db5-a94e-49c3-b48f-5f7a5569d1a2@oss.qualcomm.com>
Date: Wed, 5 Nov 2025 15:58:28 +0530
From: Mukesh Savaliya <mukesh.savaliya@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Viken Dadhaniya <viken.dadhaniya@....qualcomm.com>,
        Andi Shyti <andi.shyti@...nel.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        Wolfram Sang <wsa@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>
Cc: 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: make sure I2C hub controllers can't use
 SE DMA



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@...aro.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@....qualcomm.com>
Reviewed-by: Mukesh Kumar Savaliya <mukesh.savaliya@....qualcomm.com>>
> Konrad