Re: [PATCH v6 3/6] PCI: qcom: Add missing icc bandwidth vote for cpu to PCIe path

[Konrad Dybcio <konrad.dybcio@linaro.org>]

On 12.01.2024 16:59, Johan Hovold wrote:
> On Fri, Jan 12, 2024 at 07:52:02PM +0530, Krishna chaitanya chundru wrote:
>> CPU-PCIe path consits for registers PCIe BAR space, config space.
> 
> consits?
> 
>> As there is less access on this path compared to pcie to mem path
>> add minimum vote i.e GEN1x1 bandwidth always.
> 
> gen1 bandwidth can't be right.
> 
>> In suspend remove the cpu vote after register space access is done.
>>
>> Fixes: c4860af88d0c ("PCI: qcom: Add basic interconnect support")
>> cc: stable@vger.kernel.org
> 
> This does not look like a fix so drop the above.
> 
> The commit you refer to explicitly left this path unconfigured for now
> and only added support for the configuring the mem path as needed on
> sc8280xp which otherwise would crash.

I only sorta agree. I'd include a fixes tag but point it to either 8450
addition or original driver introduction, as this is patching up a real
hole (see my reply to Bryan).

> 
>> @@ -1573,7 +1588,7 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
>>  	 */
>>  	ret = icc_set_bw(pcie->icc_mem, 0, kBps_to_icc(1));
>>  	if (ret) {
>> -		dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
>> +		dev_err(dev, "Failed to set interconnect bandwidth for pcie-mem: %d\n", ret);
>>  		return ret;
>>  	}
>>  
>> @@ -1597,6 +1612,12 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
>>  		pcie->suspended = true;
>>  	}
>>  
>> +	/* Remove cpu path vote after all the register access is done */
>> +	ret = icc_set_bw(pcie->icc_cpu, 0, 0);
> 
> I believe you should use icc_disable() here.

Oh, TIL this exists!

Konrad