Messages in this thread | | | Date | Thu, 30 Nov 2023 11:09:59 +0100 | Subject | Re: [PATCH v4 1/3] PCI: qcom: Enable cache coherency for SA8775P RC | From | Konrad Dybcio <> |
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On 30.11.2023 06:21, Manivannan Sadhasivam wrote: > On Tue, Nov 21, 2023 at 08:08:11PM +0530, Mrinmay Sarkar wrote: >> In a multiprocessor system cache snooping maintains the consistency >> of caches. Snooping logic is disabled from HW on this platform. >> Cache coherency doesn’t work without enabling this logic. >> >> 8775 has IP version 1.34.0 so intruduce a new cfg(cfg_1_34_0) for this >> platform. Assign no_snoop_override flag into struct qcom_pcie_cfg and >> set it true in cfg_1_34_0 and enable cache snooping if this particular >> flag is true. >> > > I just happen to check the internal register details of other platforms and I > see this PCIE_PARF_NO_SNOOP_OVERIDE register with the reset value of 0x0. So > going by the logic of this patch, this register needs to be configured for other > platforms as well to enable cache coherency, but it seems like not the case as > we never did and all are working fine (so far no issues reported).
Guess we know that already [1]
The question is whether this override is necessary, or the default internal state is OK on other platforms
Konrad
[1] https://lore.kernel.org/linux-arm-msm/cb4324aa-8035-ce6e-94ef-a31ed070225c@quicinc.com/
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