linux-kernel - Re: [PATCH v2] irqchip/qcom-pdc: add support for v3.2 HW

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Date:   Wed, 23 Aug 2023 13:55:53 +0530
From:   "Maulik Shah (mkshah)" <quic_mkshah@...cinc.com>
To:     <neil.armstrong@...aro.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] irqchip/qcom-pdc: add support for v3.2 HW

Hi,

On 8/23/2023 1:16 PM, Neil Armstrong wrote:
> Hi,
>
> On 23/08/2023 07:35, Maulik Shah (mkshah) wrote:
>> Hi Neil,
>>
>> @@ -142,8 +163,17 @@ static int qcom_pdc_gic_set_type(struct irq_data 
>> *d, unsigned int type)
>>>           return -EINVAL;
>>>       }
>>> -    old_pdc_type = pdc_reg_read(IRQ_i_CFG, d->hwirq);
>>> -    pdc_reg_write(IRQ_i_CFG, d->hwirq, pdc_type);
>>> +    if (pdc_version < PDC_VERSION_3_2) {
>>> +        old_pdc_type = pdc_reg_read(IRQ_i_CFG, d->hwirq);
>>> +        pdc_reg_write(IRQ_i_CFG, d->hwirq, pdc_type);
>>> +    } else {
>>> +        u32 val;
>>> +
>>> +        val = pdc_reg_read(IRQ_i_CFG, d->hwirq);
>>> +        old_pdc_type = val & IRQ_i_CFG_TYPE_MASK;
>>> +        pdc_reg_write(IRQ_i_CFG, d->hwirq,
>>> +                  pdc_type | (val & IRQ_i_CFG_IRQ_ENABLE));
>>> +    }
>> While above is correct, i don't think we need version check in 
>> qcom_pdc_gic_set_type() as bits 0-2 are always for the type in 
>> old/new version as mentioned in v1.
>>
>> Adding one line after reading old_pdc_type should be good enough.
>
> Yes I understood, but while looking at the IRQ_i_CFG bits, I wanted to 
> keep the original
> driver behavior intact by setting remaining bits to 0.
>
> Adding this single line changes that behavior and keeps bits 3-31
> to the default register value, which may have some consequences.
>
> If you consider it's an ok change, then I'll reduce it to this single 
> line.
Yes this ok change to have single line and should not have  any 
consequences.

Thanks,
Maulik