Re: [PATCH 3/6] firmware: qcom_scm: Workaround lack of "is available" call on SC7180

From: Jeffrey Hugo <jhugo@codeaurora.org>
To: Stephen Boyd <swboyd@chromium.org>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	Elliot Berman <eberman@codeaurora.org>,
	Brian Masney <masneyb@onstation.org>,
	Stephan Gerhold <stephan@gerhold.net>,
	Douglas Anderson <dianders@chromium.org>
Subject: Re: [PATCH 3/6] firmware: qcom_scm: Workaround lack of "is available" call on SC7180
Date: Tue, 23 Feb 2021 16:38:38 -0700	[thread overview]
Message-ID: <c7fd9642-7dcb-42bc-18e9-6fd86d8f5be8@codeaurora.org> (raw)
In-Reply-To: <20210223214539.1336155-4-swboyd@chromium.org>

On 2/23/2021 2:45 PM, Stephen Boyd wrote:
> 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>
> ---
>   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 21e07a464bd9..9ac84b5d6ce0 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;
> +	}

All SC7180 targets run DT?  None have ACPI?

-- 
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.