linux-kernel - Re: [PATCH v1 1/3] spi: geni-qcom: Improve target mode allocation by using proper allocation functions

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Message-ID: <32eb6d3c-835f-44cd-9852-96ddc8661113@oss.qualcomm.com>
Date: Fri, 30 Jan 2026 12:22:43 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Praveen Talari <praveen.talari@....qualcomm.com>,
        Mark Brown <broonie@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
        bjorn.andersson@....qualcomm.com, dmitry.baryshkov@....qualcomm.com
Cc: prasad.sodagudi@....qualcomm.com, mukesh.savaliya@....qualcomm.com,
        quic_vtanuku@...cinc.com, aniket.randive@....qualcomm.com,
        chandana.chiluveru@....qualcomm.com, jyothi.seerapu@....qualcomm.com
Subject: Re: [PATCH v1 1/3] spi: geni-qcom: Improve target mode allocation by
 using proper allocation functions

On 1/29/26 4:45 PM, Praveen Talari wrote:
> Hi Konrad,
> 
> On 1/29/2026 5:12 PM, Konrad Dybcio wrote:
>> On 1/28/26 5:32 PM, Praveen Talari wrote:
>>> Hi Konrad
>>>
>>> On 1/27/2026 6:45 PM, Konrad Dybcio wrote:
>>>> On 1/22/26 4:10 PM, Praveen Talari wrote:
>>>>> The current implementation always allocates a host controller and sets the
>>>>> target flag later when the "spi-slave" device tree property is present.
>>>>> This approach is suboptimal as it doesn't utilize the dedicated allocation
>>>>> functions designed for target mode.
>>>>>
>>>>> Use devm_spi_alloc_target() when "spi-slave" device tree property is
>>>>> present, otherwise use devm_spi_alloc_host(). This replaces the previous
>>>>> approach of always allocating a host controller and setting target flag
>>>>> later.
>>>>>
>>>>> Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>
>>>>> ---
>>>>>    drivers/spi/spi-geni-qcom.c | 15 ++++++++-------
>>>>>    1 file changed, 8 insertions(+), 7 deletions(-)
>>>>>
>>>>> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
>>>>> index 0e5fd9df1a8f..f5d05025b196 100644
>>>>> --- a/drivers/spi/spi-geni-qcom.c
>>>>> +++ b/drivers/spi/spi-geni-qcom.c
>>>>> @@ -1017,6 +1017,14 @@ static int spi_geni_probe(struct platform_device *pdev)
>>>>>        struct clk *clk;
>>>>>        struct device *dev = &pdev->dev;
>>>>>    +    if (device_property_read_bool(dev, "spi-slave"))
>>>>> +        spi = devm_spi_alloc_target(dev, sizeof(*mas));
>>>>> +    else
>>>>> +        spi = devm_spi_alloc_host(dev, sizeof(*mas));
>>>>> +
>>>>> +    if (!spi)
>>>>> +        return -ENOMEM;
>>>>> +
>>>>>        irq = platform_get_irq(pdev, 0);
>>>>>        if (irq < 0)
>>>>>            return irq;
>>>>> @@ -1033,10 +1041,6 @@ static int spi_geni_probe(struct platform_device *pdev)
>>>>>        if (IS_ERR(clk))
>>>>>            return PTR_ERR(clk);
>>>>>    -    spi = devm_spi_alloc_host(dev, sizeof(*mas));
>>>>> -    if (!spi)
>>>>> -        return -ENOMEM;
>>>>
>>>> Is there a reason you're moving this code to the top of the function?
>>>
>>> When CONFIG_SPI_SLAVE is disabled, the call returns NULL; therefore, I placed this check at the start of the probe() function.
>>>
>>> ref:
>>> static inline struct spi_controller *devm_spi_alloc_target(struct device *dev, unsigned int size)
>>> {
>>>      if (!IS_ENABLED(CONFIG_SPI_SLAVE))
>>>          return NULL;
>>>
>>>      return __devm_spi_alloc_controller(dev, size, true);
>>> }
>>
>> That doesn't really matter since spi is not accessed beforehand
>> and it'd return a NULL if it failed to allocate either way
> I agree. I had also reviewed other SPI drivers as a reference for this implementation.
> 
> Do you want me to keep the change where earlier the host allocation was present, or is the current modification acceptable?

Please move it back

Konrad