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    SubjectRe: [PATCH v3 6/6] crypto: qcom: Add ACPI support
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    On 7/3/18 1:04 AM, Vinod Koul wrote:
    > Add support for probing on ACPI systems, with ACPI HID QCOM8160.
    >
    > On ACPI systems, clocks are always enabled, the PRNG should
    > already be enabled, and the register region is read-only.
    > The driver only verifies that the hardware is already
    > enabled never tries to disable or configure it.
    >
    > Signed-off-by: Timur Tabi<timur@codeaurora.org>
    > [port to crypto API]
    > Signed-off-by: Vinod Koul<vkoul@kernel.org>

    I've asked a colleague who still works at Qualcomm to test this code on
    silicon. It looks okay, but I just want to be sure.

    > + /*
    > + * ACPI systems have v2 hardware. The clocks are always enabled,
    > + * the PRNG register space is read-only and the PRNG should
    > + * already be enabled.
    > + */
    > + if (has_acpi_companion(&pdev->dev)) {
    > + val = readl(rng->base + PRNG_CONFIG);
    > + if (!(val & PRNG_CONFIG_HW_ENABLE)) {
    > + dev_err(&pdev->dev, "device is not enabled\n");
    > + return -ENODEV;
    > + }

    I'm having second thoughts about this PRNG_CONFIG_HW_ENABLE check. The
    PRNG on the QDF2400 is the same as the one on the 8996, so it should
    have the same register interface. Currently, the ACPI table points to a
    full PRNG register block, but I'm beginning to believe that it should
    instead point to a "reduced" block that doesn't have a PRNG_CONFIG register.

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