Messages in this thread | | | Subject | Re: [RESEND PATCH v17 5/5] iommu/arm-smmu: Add support for qcom,smmu-v2 variant | From | Thor Thayer <> | Date | Mon, 26 Nov 2018 08:41:51 -0600 |
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Hi Vivek,
On 11/26/18 4:55 AM, Vivek Gautam wrote: > > On 11/24/2018 12:04 AM, Will Deacon wrote: >> On Fri, Nov 23, 2018 at 03:06:29PM +0530, Vivek Gautam wrote: >>> On Fri, Nov 23, 2018 at 2:52 PM Tomasz Figa <tfiga@chromium.org> wrote: >>>> On Fri, Nov 23, 2018 at 6:13 PM Vivek Gautam >>>> <vivek.gautam@codeaurora.org> wrote: >>>>> On Wed, Nov 21, 2018 at 11:09 PM Will Deacon <will.deacon@arm.com> >>>>> wrote: >>>>>> On Fri, Nov 16, 2018 at 04:54:30PM +0530, Vivek Gautam wrote: >>>>>>> @@ -2026,6 +2027,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, >>>>>>> ARM_SMMU_V1_64K, GENERIC_SMMU); >>>>>>> ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500); >>>>>>> ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2); >>>>>>> >>>>>>> +static const char * const qcom_smmuv2_clks[] = { >>>>>>> + "bus", "iface", >>>>>>> +}; >>>>>>> + >>>>>>> +static const struct arm_smmu_match_data qcom_smmuv2 = { >>>>>>> + .version = ARM_SMMU_V2, >>>>>>> + .model = QCOM_SMMUV2, >>>>>>> + .clks = qcom_smmuv2_clks, >>>>>>> + .num_clks = ARRAY_SIZE(qcom_smmuv2_clks), >>>>>>> +}; >>>>>> These seems redundant if we go down the route proposed by Thor, >>>>>> where we >>>>>> just pull all of the clocks out of the device-tree. In which case, >>>>>> why >>>>>> do we need this match_data at all? >>>>> Which is better? Driver relying solely on the device tree to tell >>>>> which all clocks >>>>> are required to be enabled, >>>>> or, the driver deciding itself based on the platform's match data, >>>>> that it should >>>>> have X, Y, & Z clocks that should be supplied from the device tree. >>>> The former would simplify the driver, but would also make it >>>> impossible to spot mistakes in DT, which would ultimately surface out >>>> as very hard to debug bugs (likely complete system lockups). >>> Thanks. >>> Yea, this is how I understand things presently. Relying on device tree >>> puts the things out of driver's control. >> But it also has the undesirable effect of having to update the driver >> code whenever we want to add support for a new SMMU implementation. If >> we do this all in the DT, as Thor is trying to do, then older kernels >> will work well with new hardware. >> >>> Hi Will, >>> Am I unable to understand the intentions here for Thor's clock-fetch >>> design change? >> I'm having trouble parsing your question, sorry. Please work with Thor >> so that we have a single way to get the clock information. My preference >> is to take it from the firmware, for the reason I stated above. > Hi Will, > > Sure, thanks. I will work with Thor to get this going. > > Hi Thor, > Does it sound okay to you to squash your patch [1] into my patch [2] with > your 'Signed-off-by' tag? > I will update the commit log to include the information about getting > clock details from device tree. > > [1] https://patchwork.kernel.org/patch/10628725/ > [2] https://patchwork.kernel.org/patch/10686061/ >
Yes, that would be great and easier to understand than my patch on top of yours.
Additionally, can you remove the "Error:" as Will requested as part of the squash?
Thank you!
Thor
> Best regards > Vivek >> >> Will > >
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