linux-kernel - Re: [PATCH v1 1/3] PCI: qcom: Enable cache coherency for SA8775P RC

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Message-ID: <1bdf3b44-8a6f-c6d4-e86b-ec4bc0fc871f@linaro.org>
Date:   Thu, 2 Nov 2023 23:27:30 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Mrinmay Sarkar <quic_msarkar@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, mani@...nel.org, robh+dt@...nel.org
Cc:     quic_shazhuss@...cinc.com, quic_nitegupt@...cinc.com,
        quic_ramkri@...cinc.com, quic_nayiluri@...cinc.com,
        dmitry.baryshkov@...aro.org, robh@...nel.org,
        quic_krichai@...cinc.com, quic_vbadigan@...cinc.com,
        quic_parass@...cinc.com, quic_schintav@...cinc.com,
        quic_shijjose@...cinc.com,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v1 1/3] PCI: qcom: Enable cache coherency for SA8775P RC



On 02/11/2023 11:16, Mrinmay Sarkar wrote:
> 
> On 10/31/2023 10:20 PM, Konrad Dybcio wrote:
>> On 31.10.2023 16:46, Mrinmay Sarkar wrote:
>>> This change will enable cache snooping logic to support
>>> cache coherency for SA8755P RC platform.
>> 8775
>>
>>> Signed-off-by: Mrinmay Sarkar <quic_msarkar@...cinc.com>
>>> ---
>>>   drivers/pci/controller/dwc/pcie-qcom.c | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c 
>>> b/drivers/pci/controller/dwc/pcie-qcom.c
>>> index 6902e97..6f240fc 100644
>>> --- a/drivers/pci/controller/dwc/pcie-qcom.c
>>> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
>>> @@ -51,6 +51,7 @@
>>>   #define PARF_SID_OFFSET                0x234
>>>   #define PARF_BDF_TRANSLATE_CFG            0x24c
>>>   #define PARF_SLV_ADDR_SPACE_SIZE        0x358
>>> +#define PCIE_PARF_NO_SNOOP_OVERIDE        0x3d4
>>>   #define PARF_DEVICE_TYPE            0x1000
>>>   #define PARF_BDF_TO_SID_TABLE_N            0x2000
>>> @@ -117,6 +118,9 @@
>>>   /* PARF_LTSSM register fields */
>>>   #define LTSSM_EN                BIT(8)
>>> +/* PARF_NO_SNOOP_OVERIDE register value */
>> override
>>> +#define NO_SNOOP_OVERIDE_EN            0xa
>> is this actually some magic value and not BIT(1) | BIT(3)?
> we need to set 1st and 3rd bit. yes, we can use BIT(1) | BIT(3).
It would be great if you could explain what each of these bits means
separately, #defining them instead and ORing at usage time.

Konrad