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    Subject[PATCH 5.10 205/530] firmware: qcom_scm: Workaround lack of "is available" call on SC7180
    Date
    From: Stephen Boyd <swboyd@chromium.org>

    [ Upstream commit 257f2935cbbf14b16912c635fcd8ff43345c953b ]

    Some SC7180 firmwares don't implement the QCOM_SCM_INFO_IS_CALL_AVAIL
    API, so we can't probe the calling convention. We detect the legacy
    calling convention on these firmwares, because the availability call
    always fails and legacy is the fallback. This leads to problems where
    the rmtfs driver fails to probe, because it tries to assign memory with
    a bad calling convention, which then leads to modem failing to load and
    all networking, even wifi, to fail. Ouch!

    Let's force the calling convention to be what it always is on this SoC,
    i.e. arm64. Of course, the calling convention is not the same thing as
    implementing the QCOM_SCM_INFO_IS_CALL_AVAIL API. The absence of the "is
    this call available" API from the firmware means that any call to
    __qcom_scm_is_call_available() fails. This is OK for now though because
    none of the calls that are checked for existence are implemented on
    firmware running on sc7180. If such a call needs to be checked for
    existence in the future, we presume that firmware will implement this
    API and then things will "just work".

    Cc: Elliot Berman <eberman@codeaurora.org>
    Cc: Brian Masney <masneyb@onstation.org>
    Cc: Stephan Gerhold <stephan@gerhold.net>
    Cc: Jeffrey Hugo <jhugo@codeaurora.org>
    Cc: Douglas Anderson <dianders@chromium.org>
    Fixes: 9a434cee773a ("firmware: qcom_scm: Dynamically support SMCCC and legacy conventions")
    Signed-off-by: Stephen Boyd <swboyd@chromium.org>
    Link: https://lore.kernel.org/r/20210223214539.1336155-4-swboyd@chromium.org
    Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/firmware/qcom_scm.c | 18 ++++++++++++++++--
    1 file changed, 16 insertions(+), 2 deletions(-)

    diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
    index a455c22bcdbd..c5b20bdc08e9 100644
    --- a/drivers/firmware/qcom_scm.c
    +++ b/drivers/firmware/qcom_scm.c
    @@ -131,6 +131,7 @@ static enum qcom_scm_convention __get_convention(void)
    struct qcom_scm_res res;
    enum qcom_scm_convention probed_convention;
    int ret;
    + bool forced = false;

    if (likely(qcom_scm_convention != SMC_CONVENTION_UNKNOWN))
    return qcom_scm_convention;
    @@ -144,6 +145,18 @@ static enum qcom_scm_convention __get_convention(void)
    if (!ret && res.result[0] == 1)
    goto found;

    + /*
    + * Some SC7180 firmwares didn't implement the
    + * QCOM_SCM_INFO_IS_CALL_AVAIL call, so we fallback to forcing ARM_64
    + * calling conventions on these firmwares. Luckily we don't make any
    + * early calls into the firmware on these SoCs so the device pointer
    + * will be valid here to check if the compatible matches.
    + */
    + if (of_device_is_compatible(__scm ? __scm->dev->of_node : NULL, "qcom,scm-sc7180")) {
    + forced = true;
    + goto found;
    + }
    +
    probed_convention = SMC_CONVENTION_ARM_32;
    ret = __scm_smc_call(NULL, &desc, probed_convention, &res, true);
    if (!ret && res.result[0] == 1)
    @@ -154,8 +167,9 @@ found:
    spin_lock_irqsave(&scm_query_lock, flags);
    if (probed_convention != qcom_scm_convention) {
    qcom_scm_convention = probed_convention;
    - pr_info("qcom_scm: convention: %s\n",
    - qcom_scm_convention_names[qcom_scm_convention]);
    + pr_info("qcom_scm: convention: %s%s\n",
    + qcom_scm_convention_names[qcom_scm_convention],
    + forced ? " (forced)" : "");
    }
    spin_unlock_irqrestore(&scm_query_lock, flags);

    --
    2.30.2


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